HK1216468B - Circuits, methods and wireless devices for performing 2g amplification - Google Patents

Description

Circuit, method and wireless device for 2G amplification

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/038,322, filed on August 17, 2014, entitled “CIRCUITS AND METHODS FOR 2G AMPLIFICATION USING 3G/4G LINEAR PATH COMBINATION,” and U.S. Provisional Application No. 62/038,323, filed on August 17, 2014, entitled “POWER AMPLIFIER INTERFACE COMPATIBLE WITH INPUTSSEPARATED BY MODE OR FREQUENCY,” the disclosures of each of which are expressly incorporated herein by reference in their entirety.

Technical Field

This application relates to 2G amplification using a combined 3G/4G path.

Background Art

Many wireless devices are configured to support current communication standards as well as one or more older standards. For example, many 3G/4G devices are configured to support the 2G cellular standard.

Summary of the Invention

According to some embodiments, the present application relates to a front-end structure comprising a first amplification path and a second amplification path, each configured to amplify a 3G/4G signal, the first amplification path including a phase shift circuit. The front-end structure further comprises: a splitter configured to receive a 2G signal and split the 2G signal into the first amplification path and the second amplification path; and a combiner configured to combine the amplified 2G signals from the first amplification path and the second amplification path into a common output path. The front-end structure further comprises an impedance transformer implemented along the common output path to provide a desired impedance for the combined 2G signal.

In some embodiments, the splitter may include a first switch between a common input and the first amplification path, and a second switch between the common input and the second amplification path. When a 2G signal is received and split into the first amplification path and the second amplification path, each of the first switch and the second switch may be turned on.

In some embodiments, each of the first amplification path and the second amplification path may include a power amplifier (PA). The phase shift circuit may be on the input side of the PA. The phase shift circuit may include an inductor and a capacitor coupling each end of the inductor to ground.

In some embodiments, each of the first and second amplification paths may include an output matching network (OMN). In some embodiments, both OMNs may be implemented as integrated passive devices (IPDs). In some embodiments, each OMN may include an inductor and a capacitor coupling an output side of the inductor to ground.

In some embodiments, the combiner may be part of a band select switch on the output side of the PA of the first amplification path and the second amplification path. The band select switch may include a pole connected to each of the first amplification path and the second amplification path. The poles connected to the corresponding amplification paths may be existing poles for 3G/4G operation. The band select switch may also include a throw connected to the impedance transformer. The band select switch may be configured to connect each pole associated with the corresponding amplification path to a throw associated with the impedance transformer.

In some embodiments, the impedance converter may include a first inductor and a second inductor connected in series, a first capacitor coupling a node between the first inductor and the second inductor to ground, and a second capacitor coupling an output side of the second inductor to ground.

In some embodiments, the first amplification path and the second amplification path may be configured to amplify low-band (LB) and very low-band (VLB) 3G/4G signals, respectively. The 2G signals may have a frequency in the range of, for example, 820 MHz to 920 MHz. The 2G signals may include, for example, signals in the GSM 850 band or the EGSM 900 band.

In some teachings, the present application relates to a method for amplifying a 2G signal. The method includes splitting the 2G signal to produce a split signal that enters each of a first amplification path and a second amplification path, each of the first amplification path and the second amplification path being configured to amplify a 3G/4G signal. The method also includes phase shifting the split signal in the first amplification path and amplifying the split signal in each of the first amplification path and the second amplification path. The method also includes combining the amplified signals from the first amplification path and the second amplification path to produce a combined signal, and providing a desired impedance transformation for the combined signal.

In some embodiments, the amplifying step may include providing a power supply voltage to a power amplifier (PA) in each of the first amplification path and the second amplification path. In some embodiments, the method may further include adjusting the power supply voltage to increase a saturation power level (Psat) of the amplified 2G signal. The adjusting step may include increasing the power supply voltage.

In some embodiments, the present application relates to a front-end module (FEM) comprising a packaging substrate configured to house multiple components, and a power amplifier (PA) die mounted on the packaging substrate. The PA die comprises a first amplification path and a second amplification path, each configured to amplify 3G/4G signals, the first amplification path including a phase shift circuit. The FEM further comprises: a splitter configured to receive a 2G signal and split the 2G signal into the first and second amplification paths; and a band select switch configured to combine the amplified 2G signals from the first and second amplification paths into a common output path. The FEM further comprises an impedance transformer implemented along the common output path to provide a desired impedance for the combined 2G signal.

In some embodiments, the PA die of the FEM may be substantially free of a 2G amplification path for amplifying 2G signals. In some embodiments, the FEM may be substantially free of a 2G matching network associated with the 2G amplification path.

According to some teachings, the present application relates to a wireless device comprising a transceiver configured to generate a radio frequency (RF) signal and a front-end structure in communication with the transceiver. The front-end structure is configured to process 3G/4G signals and includes a first amplification path and a second amplification path, each configured to amplify the 3G/4G signal, the first amplification path including a phase shift circuit. The front-end structure also includes a splitter configured to receive a 2G signal and split the 2G signal into the first and second amplification paths; and a combiner configured to combine the amplified 2G signals from the first and second amplification paths into a common output path. The front-end structure also includes an impedance transformer implemented along the common output path to provide a desired impedance for the combined 2G signal. The wireless device also includes an antenna in communication with the front-end structure, the antenna configured to transmit the amplified 2G signal.

In some embodiments, the wireless device may be a cellular phone. In some embodiments, the cellular phone may be a 3G/4G device with 2G capabilities. In some embodiments, the cellular phone may be capable of operating in the GSM850 frequency band or the EGSM900 frequency band.

For the purpose of summarizing the present application, certain aspects, advantages, and novel features of the present invention have been described herein. It should be understood that not all of these advantages need be achieved according to any specific embodiment of the present invention. Thus, the present invention may be implemented or realized in a manner that realizes or optimizes one or a group of advantages as taught herein, without necessarily realizing other advantages as may be taught or suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a 3G/4G front-end architecture that can accommodate one or more 2G amplification paths.

FIG. 2 shows an example of a 2G path that can utilize components that are part of a 3G/4G architecture.

FIG. 3 shows an example of a combiner that can be used in the example of FIG. 2 .

FIG. 4 shows another example of a 2G path that can utilize components that are part of a 3G/4G architecture.

FIG. 5A shows a more specific example of the 3G/4G structure of FIG. 4 .

FIG. 5B shows an alternative design to the example of FIG. 5A .

FIG. 6 illustrates an example circuit that can be implemented as an impedance transformer in the examples of FIGs. 5A and 5B .

7A and 7B illustrate examples of performance that can be achieved or expected using the impedance converters of FIGs. 5A, 5B, and 6. FIGs.

FIG8 shows a graph of power amplification gain as a function of output power for the example of FIG2 for one configuration.

FIG. 9 shows a graph of power amplification gain as a function of output power for the example of FIG. 2 for another configuration.

FIG10 shows a graph of power amplification gain as a function of output power for the example of FIG2 for yet another configuration.

FIG. 11 shows a graph of power amplification gain as a function of output power for the example of FIG. 5A for one configuration.

FIG. 12 shows a graph of power amplification gain as a function of output power for the example of FIG. 5A for another configuration.

FIG13 illustrates a process that can be implemented to process 2G signals in a 3G/4G power amplifier (PA) engine.

FIG. 14 illustrates that in some embodiments, some or all of the 3G/4G architecture described herein may be implemented as a packaged module.

FIG15 illustrates an example wireless device having one or more advantageous features described herein.

DETAILED DESCRIPTION

The headings provided herein, if any, are for convenience only and do not necessarily affect the scope or meaning of the claimed invention.

Support for 2G configurations, such as the GMSK/8PSK transmit radio frequency (RF) path, in the front-end of a multi-mode multi-band (MMMB) cellular device has traditionally required a dedicated power amplifier (PA) RF block to meet efficiency and target output power requirements. Low-band (LB) 2G (e.g., low-band GSM850 and EGSM900) is particularly challenging, as it typically requires 33dBm output power at the cellular antenna, while the peak power of a typical linear 3G/4G power amplifier (PA) may be closer to 27dBm. It should also be noted that design factors such as active die area, output matching, and connectivity can have a substantial impact on the area and/or cost of such a front-end.

In some applications, 2G support can be achieved by using dedicated 2G PAs and radio frequency (RF) paths, with some impact on cost and/or size. For example, the overall size associated with a 2G PA transistor may be more than twice the size of a 3G PA transistor.

In other applications, circuit sizing of the 3G/4G linear path can be utilized. However, this technique generally involves adjusting the lossy DC-DC converter supply voltage and/or load impedance switching, which results in poor DC power consumption performance and negatively impacts the efficiency and/or linearity of the 3G/4G linear path.

1 shows that in some embodiments, the present application relates to a 3G/4G front-end architecture 100 that can accommodate one or more 2G amplification paths 104. Such an architecture may include multiple 3G/4G amplification paths 102 to provide, for example, MMMB functionality.

In some embodiments, as described herein, the 2G amplification path(s) 104 of FIG. 1 can be configured to utilize existing 3G/4G linear transmit paths and PA stages that are designed, optimized, and appropriately sized for 3G/4G performance (e.g., linearity and efficiency). Various non-limiting examples of such 2G amplification paths are described in greater detail herein.

FIG2 illustrates an example of a 2G path 104 that can utilize components that are part of the 3G/4G architecture 100. In the example of FIG2 , the first path, including PA 116 (PA1) and output matching network 118 (OMN1), is a 3G/4G path. Similarly, the second path, including PA 122 (PA2) and output matching network 124 (OMN2), is a 3G/4G path. In various examples herein, such first and second 3G/4G paths are described in the example context of low-band (LB) and very low-band (VLB) paths. However, it should be understood that one or more features of the present disclosure may also be implemented using paths associated with other frequency bands.

In the example of FIG2 , 2G path 104 may include an input 110 configured to receive a 2G signal (e.g., low-band GSM850 or EGSM900). Such a signal may be distributed via splitter 112 into a first path associated with PA1 and a second path associated with PA2. The first path is shown as including a phase shift circuit 114 before PA1 and an output matching network OMN1 after PA1. The second path is shown as including an output matching network OMN2 after PA2. The two paths are shown combined via a Wilkinson combiner 120 to produce an output 128 for the amplified 2G signal.

FIG3 illustrates an example of the Wilkinson combiner 120 of FIG2 . First and second nodes 130 and 132 can be connected to the outputs of OMN1 and OMN2, respectively, of FIG2 . These two nodes (130, 132) are shown resistively coupled via resistor R1. First node 130 is shown coupled to ground via capacitor C1, and second node 132 is shown coupled to ground via capacitor C2. Inductors L1 and L2, connected in series with each other and in parallel with R1, are shown coupling first and second nodes 130 and 132 such that output 128 is located at a node between L1 and L2. Output node 128 is shown coupled to ground via capacitor C3.

Note that in the example of FIG2 , the splitter 112 (e.g., one or more switches) can be configured such that a given 2G signal is routed only to the first path, only to the second path, or to both the first and second paths. Utilizing these routing options, and in the example context of the first and second paths being 3G/4G LB and VLB paths, Table 1 lists examples of saturated power level (Psat) performance that can be achieved or expected for the configurations of FIG2 and 3 when amplifying a 2G signal (824 MHz or 915 MHz).

Table 1

The following discussion can be made with reference to Table 1. Due to the lower load line, the "VLB only" case exhibits a higher Psat than the "LB only" case in the simulation bench. A lossless Wilkinson combiner (120 in FIG3 ) is simulated using ideal resistors, inductors, and capacitors (R1=100 ohms, C1=C2=2.6 pF, L1=L2=13 nH, C3=5.1 pF). Accordingly, in some embodiments, the aforementioned design utilizing a Wilkinson combiner may include at least four SMT components, a resistor with a high power rating, and two additional switch arms (e.g., for separating incoming 2G signals).

FIG4 illustrates an example of a 2G path 104 that can utilize components that are part of the 3G/4G architecture 100. In the example of FIG4 , an additional shared throw can be implemented on an existing post-PA band select switch to allow two low-band 3G/4G amplifiers to be simultaneously connected to a common output pole of the post-PA band select switch. From this output pole, an impedance transformation network can be provided to optimally combine the outputs of the two PAs, thereby achieving the higher output power specifications typically associated with the 2G low-band. Furthermore, the post-PA band select switch can effectively isolate the aforementioned combiner network from other 3G/4G-optimized PAs and associated paths; thus, there is little or no impact on the performance of various 3G/4G operations.

4 , the first path including PA 156 (PA1) and output matching network 158 (OMN1) is a 3G/4G path. Similarly, the second path including PA 162 (PA2) and output matching network 164 (OMN2) is a 3G/4G path. In various examples herein, such first and second 3G/4G paths are described in the context of low-band (LB) and very low-band (VLB) paths. However, it should be understood that one or more features of the present disclosure may also be implemented using paths associated with other frequency bands.

In the example of FIG4 , 2G path 104 may include an input 150 configured to receive a 2G signal (e.g., low-band GSM850 or EGSM900). Such a signal may be split into a first path associated with PA1 and a second path associated with PA2 via a splitter 152. The first path is shown as including a phase shift circuit 154 before PA1 and an output matching network OMN1 after PA1. The second path is shown as including an output matching network OMN2 after PA2. The two paths are shown combined by a combiner 160, which includes an impedance transformer 166 configured to generate an output 168 for the amplified 2G signal.

Figure 5A shows a more specific example of the 3G/4G structure 100 of Figure 4. In Figure 5A, the splitter 152, the phase shift circuit 154, the OMNs 156 and 164, and the combiner 160 of Figure 4 are generally indicated by the same reference numerals.

FIG5A shows that in some embodiments, the splitter 152 may include first and second switches S1 and S2 connected to a common input 150. The first switch S1 is shown in series with the phase shift circuit 154 and the first PA 156 (PA1). The second switch S2 is shown in series with the second PA 162 (PA2). Thus, the operation of the first and second switches S1 and S2 can route incoming 2G signals to only the first PA (PA1) (e.g., S1 is on, S2 is off), only the second PA (e.g., S1 is off, S2 is on), or both the first and second PAs (PA1 and PA2) (e.g., S1 is on, S2 is on). In the example shown in FIG5A, both S1 and S2 are on; therefore, the incoming 2G signal is routed to both the first and second PAs (PA1 and PA2).

FIG5A shows that in some embodiments, phase shift circuit 154 may include an inductor L1, with each end of L1 coupled to ground via a capacitor (C1 or C1'). In the context of the first and second PAs (PA1 and PA2) being LB and VLB PAs, and the 2G signal being a low-band signal (e.g., 824 MHz or 915 MHz), example values for L1, C1, and C1' may be as follows: L1 = 7.9 nH, C1 = C1' = 2.1 pF. This example configuration of phase shift circuit 154 can provide approximately 60 degrees of phase shift for the low-band 2G signal. It should be understood that phase shift circuit 154 can be configured to provide different amounts of phase shift and/or accommodate signals of different frequencies.

FIG5A shows that in some embodiments, each of the first and second PAs (PA1 and PA2) can include one or more stages. For example, each PA can include a driver stage and an output stage. In such a configuration, each PA in FIG5A can be provided with a supply voltage VCC1 for the driver stage and a supply voltage VCC2 for the output stage.

5A shows that in some embodiments, both OMNs 158/164 may be implemented as integrated passive devices (IPDs) 192. Such IPDs may also include matching networks for other 3G/4G PAs.

FIG5A shows that in some embodiments, phase shift circuit 154, PAs (PA1, PA2), and IPD 192 with OMNs 158 and 164 can be functionally considered a PA block 190. Such functional blocks can be implemented as one or more dies. For example, IPD 192 and the die with PAs can be stacked to reduce the lateral footprint. In another example, IPD 192 and band select switch 194 of FIG5A can be stacked. As can be seen, a variety of different configurations can be implemented.

FIG5A illustrates that, in some embodiments, the combiner 160 of FIG4 can be implemented in a band select switch 194. For example, the outputs of the OMNs 158 and 164 of the first and second paths are shown connected to their respective poles, which may or may not already be present in the band select switch 194 for 3G/4G operation. The respective throws of the band select switch 194 are shown connected to their respective duplexers 198. Additional throws 196 can be provided in the band select switch 194, which can be connected to the impedance transformers 166 described herein. Thus, the band select switch 194 can operate to form connections between the output of the first OMN 158 and the throw 196, and between the output of the second OMN 164 and the throw 196, thereby providing a combined path including the impedance transformer 166 and the output 168.

5A , duplexer 198 is shown to include channels such as bands B8, B26, B20, B17, B27, B13, B28, B12, and B28B/B29. It will be understood that a greater or lesser number of bands, and/or other bands, may be implemented and switched by band select switch 194.

Figure 5B shows an alternative design to the example of Figure 5 A. More particularly, the example of Figure 5B is shown as including a combiner 160 that is different from the combiner of Figure 5 A. For illustration, the splitter 152, PA block 190, and duplexer 198 of Figure 5B may be similar to those of Figure 5A.

In the example of FIG5B , similar to the example of FIG5A , the outputs of OMNs 158 and 164 for the first and second paths are shown connected to their respective poles. These poles may or may not already be present in the band select switch 194 for 3G/4G operation. However, in the band select switch 194 of FIG5B , there are two throws 193a and 193b that can be connected to these two poles. Throw 193a is shown connected to the input of a first matching network 195a, and throw 193b is shown connected to the input of a second matching network 195b. The outputs of the first and second matching networks 195a and 195b are shown connected to a common node 197. Therefore, the combiner in the example of FIG5B can include the aforementioned paths between OMNs 158 and 164 and the common node 197.

In Figure 5B, an impedance transformer 166 is shown implemented between common node 197 and output 168. Such an impedance transformer may be the same as the example 25 ohm to 50 ohm transformer of Figure 5A, or it may be different.

FIG6 shows an example circuit that can be implemented as the impedance converter 166 of FIG5A and FIG5B. Such a circuit can include inductors L4 and L5 connected in series between the common throw 196 and the output 168 of the band select switch 194 of FIG5A and between the common node 197 and the output 168 of FIG5B. The impedance converter circuit 166 is shown to also include a capacitor C4 coupling the node between L4 and L5 to ground and a capacitor C5 coupling the output node 128 to ground.

In FIG5A , the impedance transformer 166 is shown as providing a transformation from 25 ohms (on the common node (196) side) to 50 ohms (on the output (168) side). In such an example context, the values of L4, L5, C4, and C5 in FIG6 may be as follows. Ideally, L4 may be approximately 3.74 nH, L5 may be approximately 7.91 nH, C4 may be approximately 6.33 pF, and C5 may be approximately 2.99 pF. When implemented as an SMT inductor and capacitor with a Q factor of approximately 40, L4 may be approximately 3.6 nH, L5 may be approximately 7.7 nH, C4 may be approximately 6.2 pF, and C5 may be approximately 3 pF. Such an example configuration of the impedance transformer 166 may enhance the output power of low-band 2G signals processed as described herein. It should be understood that the impedance transformer 166 may be configured to provide different transformations and/or accommodate signals of different frequencies.

It should be understood that the impedance transformer 166 of Figures 4-6 can be implemented using a variety of other technologies, including, for example, transmission lines, lumped element reactive transformation, and transformers based on coupled coils, which can have various winding relationships to achieve different impedance transformations. The required or desired phase and amplitude relationship between the two PA paths can be achieved by, for example, applying phase shifts and amplitude adjustments at the input of one or the other, or by combining various stages relative to each other to avoid output losses. In some applications, phase and amplitude adjustment networks can also be implemented on the output side of the (respective) PA, with some loss penalty.

7A and 7B illustrate examples of performance that can be achieved or expected using the impedance transformer 166 of FIGs. 5A, 5B, and 6 using the aforementioned SMT embodiment (e.g., Q=40). FIG7A shows a graph of the S11 parameter (reflection coefficient) as a function of frequency, demonstrating broadband properties. FIG7B shows a graph of insertion loss as a function of frequency, demonstrating a reasonable insertion loss of approximately 0.3 dB.

8-12 show graphs of power amplifier gain as a function of output power for various example configurations described herein. More specifically, FIG8 is for the example of FIG2 with only the VLB path after the OMN (124); FIG9 is for the example of FIG2 with only the LB path (no phase shift) after the OMN (118); FIG10 is for the example of FIG2 with VLB and LB (290 degrees phase shift) after the Wilkinson combiner (120); FIG11 is for the example of FIG5A with VLB and LB (60 degrees phase shift) after the impedance converter (166) (with 0.3 dB loss) with VCC (e.g., VCC2 in FIG5A) at 3.4 V; and FIG12 is for the example of FIG5A with VLB and LB (60 degrees phase shift) after the impedance converter (166) (with 0.3 dB loss) with VCC increased to 3.8 V. The saturation power level (Psat) can be obtained from these graphs. Table 2 includes an overview of such Psat values for the graphs shown in Figures 8-12. Note that the first four rows of Table 2 are identical to Table 1. Note also that for purposes of illustration, the example configuration of Figure 5A is sometimes referred to herein as a load sharing configuration when both the first and second paths (associated with PA1 and PA2) are active.

Table 2

Based on the performance overview of Table 2, it can be seen that the load-sharing configuration of FIG5A provides good performance at a similar level to that provided by the lossless Wilkinson combiner example of FIG2. Compared to the Wilkinson combiner example of FIG2, which likely requires multiple SMT components and high-power-rated resistors (and additional space to accommodate these components), the load-sharing configuration of FIG5A can be implemented with far fewer additional components. Therefore, the load-sharing configuration of FIG5A can provide cost and space savings.

It should be noted that one or more features of the present application can advantageously allow for the elimination of one or more dedicated 2G power amplifiers and associated RF paths, etc., by effectively combining existing paths. As described herein, such existing paths can maintain their originally designed optimal performance in 3G/4G mode.

It should also be noted that although various examples are described herein in the context of 3G/4G PAs, paths, etc., it should be understood that these PAs, paths, etc. can be configured for 3G operation, for 4G operation, or any combination thereof. It should also be understood that one or more features of the present application can also be applied to configurations involving other generations of cellular standards used in the past, currently in use, to be defined, and to be used in the future, or any combination thereof.

It should also be noted that, as can be seen in the example described with reference to FIG12 and Table 2, changes in the power supply VCC can affect the amplification performance of the 2G signal. In some cases, such adjustments to VCC may negatively impact 3G/4G efficiency/linearity performance. Even in such cases, the performance tradeoff may be acceptable, especially considering that the processing of the 2G signal described herein can have minimal impact on the area and cost of the 3G/4G path.

It should also be noted that while various examples are described herein in the context of two parallel amplification paths in a 3G/4G architecture, one or more features of the present disclosure may also be implemented in other applications. For example, multi-PA combining methods for linearization, such as the Doherty technique, which applies different phase adjustments and amplitude balancing to achieve backed-off efficiency advantages, may utilize one or more features of the present disclosure.

It should also be noted that while various examples are described in the context of two amplification paths, one or more features of the present application can also be implemented in systems involving more than two amplification paths. For example, one or more features of the present application can be used to extend the power combining advantages to much higher power levels of a combined PA utilizing three or more PA paths.

Figure 13 illustrates a process 300 that can be implemented to process 2G signals in a 3G/4G PA engine. In block 302, a 2G signal may be provided to the input of a 3G/4G power amplifier (PA). In block 304, the 2G signal may be separated into first and second paths. In block 306, a phase shift may be introduced into the 2G signal in the first path. In block 308, the 2G signal in each of the first and second paths may be amplified. In block 310, each amplified 2G signal may be impedance matched. In block 312, the amplified 2G signals from the first and second paths may be combined. In block 314, impedance transformation may be performed on the combined 2G signal. In block 316, the impedance-transformed 2G signal may be routed to an antenna for transmission.

In some embodiments, one or more features described herein in connection with 2G amplification utilizing 3G/4G path combining may be implemented in a PA system having an interface compatible with multiple inputs separated by mode or frequency. Additional details regarding such a PA system are described in U.S. Provisional Application No. 62/038,323, filed on August 17, 2014, entitled “POWER AMPLIFIER INTERFACE COMPATIBLE WITH INPUTS SEPARATED BY MODE OR FREQUENCY,” and its corresponding U.S. Application entitled “POWER AMPLIFIER INTERFACE COMPATIBLE WITH INPUT SEPARATED BY MODE OR FREQUENCY,” each of which is expressly incorporated herein by reference in its entirety and is to be considered a part of the specification of this application.

FIG14 illustrates that in some embodiments, all or some of the 3G/4G architecture described herein can be implemented as a packaged module. For example, a front-end module (FEM) 350 may include a package substrate 352 configured to house multiple components. Such a module includes, for example, a PA die 354 having multiple amplification paths for implementing 3G/4G MM/MB operations. Where a 2G PA is traditionally implemented on such a die, by utilizing one or more of the techniques described herein, some or all of such a 2G PA can be eliminated, and 2G functionality can be achieved. Consequently, the size and cost of such a PA die can be reduced. Where a 2G PA is traditionally implemented on a separate die, the size of such a die can be reduced or eliminated for similar reasons. Consequently, module size and cost can be reduced. It should also be noted that one or more components traditionally mounted on the package substrate 352 to implement 2G impedance matching and/or filtering functions can also be reduced or eliminated, thereby reducing module size and cost.

The example FEM 350 is shown as also including a band select switch 358. As described herein, such a switch may be configured to provide combining functionality for 2G signals routed to two or more amplification paths.

The example FEM 350 is shown as also including an impedance transformer 360. As described herein, such a transformer may be configured to improve output power for transmission of 2G signals processed by a 3G/4G engine.

The example FEM 350 is shown as also including a filter and duplexer assembly 362. Such filters and duplexers provide filtering and duplexing functions for 3G/4G signals as well as 2G signals being processed by the 3G/4G engine.

The example FEM 350 is shown as also including an antenna switch 364. Such a switch may be configured to route various 3G/4G signals as well as the 2G signals being transmitted.

In some embodiments, devices and/or circuits having one or more features described herein may be included in an RF device such as a wireless device. Such devices and/or circuits may be implemented directly in the wireless device in the form of modules described herein or in some combination thereof. In some embodiments, such a wireless device may include, for example, a cellular phone, a smartphone, a handheld wireless device with or without telephone functionality, a wireless tablet, and the like.

FIG15 illustrates an example wireless device 400 having one or more advantageous features described herein. In the context of a module having one or more features described herein, such a module may be generally represented by a dashed box 350 and may be implemented as a front-end module (FEM) such as a front-end module including a duplexer (FEMiD).

Each PA 370 can receive its corresponding RF signal from a transceiver 410, which is configurable and operable to generate RF signals to be amplified and transmitted, as well as to process received signals. Transceiver 410 is shown interfacing with a baseband subsystem 408, which is configured to provide conversion between data and/or voice signals intended for a user and RF signals intended for transceiver 410. Transceiver 410 is also shown connected to a power management component 406, which is configured to manage power for operation of the wireless device. Such power management can also control the operation of baseband subsystem 408 and module 350.

The baseband subsystem 408 is shown connected to the user interface 402 to implement various inputs and outputs of voice and/or data provided to and received from the user. The baseband subsystem 408 can also be connected to the memory 404, which is configured to store data and/or instructions to implement the operation of the wireless device and/or provide storage for user information.

In the example wireless device 400, the outputs of the various PAs 370 are shown matched (via respective matching circuits 372) and routed to the antenna 416 via the band select switch 358, their respective duplexers 362, and the antenna switch 364. In some embodiments, each duplexer 362 may allow simultaneous transmit and receive operations to be performed utilizing a common antenna, such as 416. In FIG15 , received signals are shown routed to an “Rx” path (not shown), which may include, for example, a low noise amplifier.

In the example wireless device 400, one or more phase shift circuits 154 may be implemented at the input of each PA 370 to facilitate the processing of 2G signals described herein. Furthermore, a band select switch 358 may be configured to provide combining functionality for two or more amplification paths described herein. Furthermore, an impedance transformer 166 may be implemented in the combining path from the band select switch 358 to facilitate the processing of 2G signals described herein. In some embodiments, such an impedance transformer may be routed directly to the antenna switch 364 to enable transmission via the antenna 416.

Many other wireless device configurations can utilize one or more features described herein. For example, a wireless device need not be a multi-band device. In another example, a wireless device can include additional antennas, such as a diversity antenna, and additional connectivity features, such as Wi-Fi, Bluetooth, and GPS.

Unless the context clearly requires otherwise, throughout the specification and claims, the terms "comprising", "including", "comprising", etc. should be understood in an inclusive sense, that is, in the sense of "including but not limited to", as opposed to an exclusive or exhaustive sense. The term "coupled" as generally used herein means that two or more elements can be connected directly or by means of one or more intervening elements. In addition, when used in this application, the terms "herein", "above", "below" and terms of similar meaning should refer to this application as a whole, rather than to any particular part of this application. Where the context permits, terms using the singular or plural in the description above may also include the plural or singular, respectively. The term "or" when referring to a list of two or more items covers all of the following interpretations thereof: any item in the list, all items in the list, and any combination of items in the list.

The above detailed description of the embodiments of the present invention is not intended to be exhaustive or to limit the present invention to the precise form disclosed above. Although the specific embodiments of the present invention and the examples for the present invention have been described above for illustrative purposes, as will be appreciated by those skilled in the art, various equivalent modifications within the scope of the present invention are feasible. For example, although processes or blocks have been presented in a given order, alternative embodiments can perform processes with steps in different orders, or adopt systems with blocks in different orders, and some processes or blocks can be deleted, moved, added, subtracted, combined and/or modified. Each of these processes or blocks can be implemented in a variety of ways. Similarly, although processes or blocks are sometimes shown as being performed serially, on the contrary, these processes or blocks can also be performed in parallel, or can be performed at different times.

The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above.The elements and acts of the various embodiments described above can be combined to provide further embodiments.

Although some embodiments of the present invention have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of the present disclosure. Indeed, the novel methods and systems described herein may be implemented in a variety of other forms; furthermore, various omissions, substitutions, and changes in the form of the methods and systems described herein may be made without departing from the spirit of the present disclosure. The accompanying drawings and their equivalents are intended to encompass such forms or modifications as would fall within the scope and spirit of the present disclosure.

Claims (23)

1. A front-end structure, comprising: The first amplification path has a first power amplifier configured to support either or both of 3G and 4G modes, and includes a phase-shifting circuit. The second amplification path has a second power amplifier configured to support either or both of 3G and 4G modes. A splitter is configured to receive a 2G signal at a common input and split the 2G signal into a first amplification path and a second amplification path, such that the first power amplifier and the second power amplifier amplify corresponding portions of the 2G signal. A combiner, which is part of a band selection switch on the output side of the power amplifiers in the first and second amplification paths, is configured to combine corresponding amplified 2G signals from the first and second power amplifiers into a common output path to provide a combined 2G signal; and An impedance transformer is implemented along the common output path to provide the required impedance for the combined 2G signal. 2. The front-end structure of claim 1, wherein the splitter includes a first switch between the common input and the first amplification path and a second switch between the common input and the second amplification path. 3. The front-end structure of claim 2, wherein the splitter is configured such that when the 2G signal is received at the common input and split into the first amplification path and the second amplification path, each of the first switch and the second switch is turned on. 4. The front-end structure as claimed in claim 1, wherein the phase-shifting circuit is located on the input side of the first power amplifier. 5. The front-end structure of claim 4, wherein the phase-shifting circuit includes an inductor and a capacitor coupling each end of the inductor to ground. 6. The front-end structure of claim 1, wherein each of the first and second amplification paths further includes an output matching network. 7. The front-end structure of claim 6, wherein each output matching network includes an inductor and a capacitor coupling the output side of the inductor to ground. 8. The front-end structure of claim 1, wherein the frequency band selection switch comprises a plurality of throws, each throw being connected to one of a plurality of duplexers. 9. The front-end structure of claim 8, wherein the frequency band selection switch includes a blade connected to each of the first amplification path and the second amplification path. 10. The front-end structure as claimed in claim 9, wherein the blade connected to the corresponding amplification path is an existing blade for 3G/4G operation. 11. The front-end structure of claim 9, wherein the frequency band selection switch further includes a throw connected to the impedance transformer. 12. The front-end structure of claim 11, wherein the band selection switch is configured to connect each blade associated with a corresponding amplification path to a throw associated with the impedance transformer. 13. The front-end structure of claim 1, wherein the impedance transformer includes a first inductor and a second inductor connected in series, a first capacitor coupling the node between the first inductor and the second inductor to ground, and a second capacitor coupling the output side of the second inductor to ground. 14. The front-end structure as described in claim 1, wherein the first amplification path and the second amplification path are respectively configured to amplify low-frequency band and very low-frequency band 3G/4G signals. 15. A method for amplifying a 2G signal, the method comprising: The 2G signal received at the common input is separated to generate a separate signal for each of a first amplification path and a second amplification path. The first amplification path has a first power amplifier configured to support either or both of 3G and 4G modes and includes a phase-shifting circuit. The second amplification path has a second power amplifier configured to support either or both of 3G and 4G modes. The corresponding separated signals are phase-shifted in the phase-shifting circuit of the first amplification path; The corresponding separated signals are amplified in the first power amplifier of the first amplification path and in the second power amplifier of the second amplification path; A combiner is used to combine amplified, separate signals from the first power amplifier and the second power amplifier into a common output path to provide a combined signal. The combiner is part of a band selection switch on the output side of the power amplifiers in the first and second amplification paths. Provide the required impedance transformation for the combined signal. 16. The method of claim 15, wherein the amplification step includes providing a power supply voltage to each of the first power amplifier and the second power amplifier. 17. The method of claim 16, further comprising adjusting the power supply voltage to increase the saturation power level of the amplified discrete signal. 18. A front-end module, comprising: A packaging substrate configured to accommodate multiple components; A power amplifier chip is mounted on the package substrate and includes a first amplification path and a second amplification path. The first amplification path has a first power amplifier configured to support either or both of 3G and 4G modes and includes a phase-shifting circuit. The second amplification path has a second power amplifier configured to support either or both of 3G and 4G modes. A splitter is configured to receive a 2G signal at a common input and split the 2G signal into a first amplification path and a second amplification path, such that the first power amplifier and the second power amplifier amplify corresponding portions of the 2G signal; A frequency band selection switch is configured to combine the corresponding amplified 2G signals from the first power amplifier and the second power amplifier into a common output path to provide a combined 2G signal; and An impedance transformer is implemented along the common output path to provide the required impedance for the combined 2G signal. 19. The front-end module of claim 18, wherein the power amplifier chip does not have a dedicated 2G amplification path for amplifying the 2G signal. 20. A wireless device, comprising: transceiver; A front-end structure communicating with the transceiver, the front-end structure including a first amplification path and a second amplification path, the first amplification path having a first power amplifier configured to support either or both of 3G and 4G modes, and including a phase-shifting circuit; the second amplification path having a second power amplifier configured to support either or both of 3G and 4G modes; the front-end structure further including a splitter configured to receive a 2G signal at a common input and split the 2G signal into the first amplification path and the second amplification path, such that the first power amplifier and the second power amplifier amplify corresponding portions of the 2G signal; the front-end structure further including a combiner, which is part of a band selection switch on the output side of the power amplifiers of the first amplification path and the second amplification path, and configured to combine the corresponding amplified 2G signals from the first power amplifier and the second power amplifier into a common output path to provide a combined 2G signal; the front-end structure further including an impedance transformer implemented along the common output path to provide the required impedance for the combined 2G signal; and An antenna communicating with the front-end structure, the antenna being configured to transmit at least the combination of 2G signals. 21. The wireless device of claim 20, wherein the wireless device is a cellular phone. 22. The wireless device of claim 21, wherein the cellular phone is a 3G/4G device with 2G capability. 23. The wireless device of claim 22, wherein the cellular phone is capable of operating in the GSM 850 band or the EGSM 900 band.