CN100477496C - Apparatus and methods for electromagnetic processing of input signal - Google Patents

Abstract

An apparatus and method for electromagnetic processing of an input signal (a) are shown. The apparatus includes: a plurality of independently controllable current sources (25a-g), each current source being activated according to a corresponding digital amplitude signal among a plurality of digital amplitude signals representing the amplitude characteristics of the input signal; when activated, a plurality of output signals are generated based on an analog phase signal representing the phase characteristics of the input signal; and the plurality of output signals are directly combined to generate a combined output signal (b).

Description

Apparatus and method for electromagnetic processing of input signals

technical field

The present invention generally relates to the adjustment of linear signals, and more particularly to the amplification and attenuation of linear signals.

Background technique

Generally speaking, conditioning (amplifying or attenuating) electromagnetic signals is a function of an electronic component or system. Tuning can be used for any number of systems, and is usually accomplished by linear or non-linear techniques. Linear techniques generally provide an output signal that is very close to the input signal except in magnitude. Nonlinear techniques generally provide output signals that do not have close proximity to the input signal.

Non-linear or linear amplifiers may be useful. Nonlinear amplifiers can be used for on/off amplification—that is, in situations where it is not necessary to produce an exact amplification of the input signal, but only to amplify the signal. Linear amplifiers can be used in situations where accurate, amplified reproduction is desired.

So, when accurate reproduction is desired, a linear amplifier is desired. However, the low efficiency of a linear amplifier makes its use undesirable in some situations. Efficiency refers to the amplifier's ability to convert DC input power to output power. A linear amplifier is less efficient than a nonlinear amplifier because it consumes more power than a nonlinear amplifier while outputting a signal of the same strength. Also, even when not amplifying, linear amplifiers require quiescent current, or current from the power supply. Non-linear amplifiers can be desirable in applications with limited power sources, such as battery power, because non-linear amplifiers typically require little or no quiescent current.

However, in some fields of signal processing, such as radio frequency (RF), non-linear techniques produce less undesirable results. For example, although linear amplifiers are desirable in RF receivers due to their accurate signal reproduction, the power consumption required by linear amplifiers limits their use, especially in portable, battery-operated devices.

Attempts to overcome these difficulties have been made in the prior art. For example, amplifier combining—using multiple amplifiers to amplify the same signal—is a way to try to balance the interests of linearity and nonlinearity. However, to date these attempts have been limited by various difficulties. For example, amplifier combining methods use components such as transformers or quarter wave lines to sum the outputs of amplifiers in order to drive a load. These components add to the cost and size of the amplifier array.

Therefore, it would be helpful for prior art signal conditioning if linear amplifier techniques could be used in conjunction with nonlinear techniques to provide efficient amplification techniques.

Contents of the invention

Embodiments of the invention include apparatus and methods for electromagnetic processing of an input signal (a). The apparatus includes a plurality of independently controllable current sources (25a-g), each current source activated in response to a corresponding one of a plurality of digital amplitude signals representative of the input signal The amplitude characteristic, when activated, generates a plurality of output signals based on an analog phase signal representative of the phase characteristic of the input signal, and the plurality of output signals are directly combined to generate a combined output signal (b).

A preferred embodiment of the present invention provides an amplifier that combines the relative accuracy of a linear amplifier with the relative efficiency and power consumption of a nonlinear amplifier.

The amplifier of the preferred embodiment includes one or more non-linear current sources. The current sources are enabled and/or disabled as desired by one or more characteristics of the input signal. In a particularly preferred embodiment, outputs from one or more current sources are combined to drive a load. If multiple current sources are used, the current sources may be weighted to contribute different amounts of current to the output. By combining the outputs from a current source or sources, a linear amplification of the signal is provided. Additionally, linear attenuation is also possible in different embodiments.

Description of drawings

Figure 1 shows a preferred embodiment.

FIG. 2 shows a schematic diagram of the operation of the embodiment of FIG. 1 .

Figure 3 shows a preferred embodiment.

4A-B show the output characteristics of current sources with regions A and A/2, respectively.

Detailed ways

Embodiments of the invention include devices, methods and products for linear signal conditioning. The term "signal" as used herein should be broadly construed to include any means of conveying data from one place to another, such as electric currents or electromagnetic fields, including, but not limited to, switching on and off direct or alternating current or including An electromagnetic carrier wave of one or more data streams. For example, data can be superimposed on a carrier current or carrier wave by means of modulation, which can be done in analog or digital form. The term "data" as used herein should also be broadly interpreted to include any type of message or other information, such as, without limitation, audio, text and/or video such as sounds.

Figure 1 shows a preferred embodiment. The input signal a is supplied to the digital signal processor 10 . The digital signal processor 10 includes an analog-to-digital converter 11 for digitizing the signal, eg using Cartesian coordinates or I, Q data. Cartesian to polar converter 12 then receives the I,Q data and converts it to polar coordinates. It should be noted that in other embodiments, the digitized representation of the signal may be provided to a Cartesian to polar converter, if desired. In these embodiments, the digital representation can be generated in a variety of ways known in the art. Also, although this embodiment has been described as using digitized signals and I, Q data, and polar coordinate data, those of ordinary skill in the art will appreciate that other embodiments are not limited thereto, and that any digital or analog wave form, or their combination.

Returning now to the embodiment of FIG. 1, the Cartesian to polar converter 12 outputs digitized signals in polar coordinates, for example in the form R, P(sin) and P(cos). In this example, the R coordinate represents the amplitude characteristic of the signal. The P(sin) and P(cos) coordinates represent the phase characteristics of the signal. It should be noted that "characteristic" as used herein refers to an electromagnetic signal characteristic such as frequency, voltage, amplitude (including amplitude and envelope), phase, current, waveform, or pulse. Other embodiments may derive one or more signal characteristics from the input signal as desired.

Turning briefly to FIG. 2 , there is shown a schematic diagram of a signal that has been converted in accordance with the embodiment of FIG. 1 . The input signal a has been converted into a magnitude component m comprising the magnitude characteristic of the input signal at period t ₁ and a phase component comprising the phase characteristic of the carrier at the same period. By means of a preferred embodiment, the output signal b after amplification is shown. It should be noted that in this and other embodiments, time periods are desired. For example, some embodiments may use different sampling rates to derive the magnitude and phase characteristics of the signal in order to maximize the resolution of the signal, to maximize the speed of operation, and the like. These sampling rates may also be determined dynamically in various embodiments, so they vary during operation. In a preferred embodiment, the division of the input signal is synchronized in order to maximize the accuracy of the output and minimize any distortion.

Returning now to Figure 1, the amplitude and phase characteristics are then sent through separate paths. Along path a ^m , via converter 13, the amplitude characteristic of the input signal is converted into a digital pulse comprising a digital word quantized into bits B ₀ to B _n-1 , having the most significant bit ("MSB") to the least significant bit (“LSB”). In different embodiments, the digital words may be of different lengths. In general, the longer the word, the more accurately the input signal can be reproduced. The digital word provides an indication signal or controls attenuation and/or amplification in a manner further described below. Of course, in other embodiments, differently composed digital words may be used, as well as other types of derivation and/or provision of amplitude or other signal characteristics, as described further below.

In the embodiment of Fig. 1, seven control assembly lines a ^m 1 - a ^m 7 leading from the converter 13 are shown. In the preferred embodiment, the number of these control component lines depends on the word resolution. In the preferred embodiment, the words have a resolution of seven bits. It should be noted in Figure 1 that for ease of viewing the figure, the control assembly lines are consolidated into a single path ^am leading to the control assemblies 22a-g. However, in an embodiment, as described further below, the control assembly wires are not combined, but are instead individually fed to the control assembly.

The phase characteristic traverses the path a ^p . Here, the phase characteristic is first modulated into a wave by a digital-to-analog converter 18 and a synthesizer (which in a particularly preferred embodiment is a voltage-controlled oscillator). The combiner 20 provides an output wave consisting of phase information. This output wave has a constant envelope, ie its amplitude does not vary, however, it has the phase characteristics of the original input wave, and is delivered to the driver 24 and then the driver lines a ^p 1 - a ^p 7 . Said waves split among the driver lines are then fed into the current sources 25a-25g and will potentially be used to drive the current sources 25a-25g as further described below. In other embodiments, other sources of other wave characteristics besides phase characteristics may also be used.

It should be noted that in this embodiment, transistors may be used as the current sources 25a-25g. Additionally, in other embodiments, one or more transistors of a segment may be used as current sources 25a-25g as appropriate. The current sources 25a-25g need not be configured to behave like voltage sources, for example saturating the transistors, which would interfere with the desired current combination of the sources.

Path ^am (including control assembly lines ^am 1- ^am 7 as described above) terminates at control assembly current sources 22a-g. In a particularly preferred embodiment there is a switching transistor, and preferably a current source, although other sources of other wave characteristics and other adjustment schemes may be used in other embodiments as described further below. The control components 22a-g are switched by the bits of the digital word output from the amplitude component and regulated by the digital word output from the amplitude component. If the bit is "1" or "high", the corresponding control component is turned on, so current flows from that control component along the bias control lines 23a-g to the appropriate current source 25a-g. As noted above, the length of a digital word may vary, so the number of bits, control components, control component lines, driver lines, bias control lines, current sources, etc. may vary accordingly in different embodiments. Also, there does not have to be a one-to-one correspondence among digital word resolutions, components, lines, and current sources in different embodiments.

If the control component is on, the current sources 25a-g receive current from the control component and each current source is thus adjusted according to that component. In a particularly preferred embodiment, a suitable control component provides a bias current to the current source, as further described below, so the control component may be referred to as a bias control circuit, and the plurality of control components act as a bias network. In some embodiments, it may be desirable to statistically or dynamically assign one or more bias control circuits to one or more current sources using a switch network, if desired.

Returning now to the embodiment of FIG. 1 , each current source acts as a potential current source and is capable of generating current output to current source lines 26a-g, respectively. Each current source may or may not act as a current source and therefore may or may not generate current as it is regulated by an appropriate indication signal, or digital word value of the adjustment control component. Activation of any segment, and generation of current from that segment, is dependent on the value of the appropriate bit from the digital representation of the amplitude component adjusting the appropriate control component. It should be noted that in the preferred embodiment, the current source is not an amplifier or amplifiers, but multiple current sources acting as amplifiers, as described herein. In fact, in preferred embodiments, amplification and/or attenuation may be considered functions of those embodiments, thus amplifiers and/or attenuators may be considered electronic components or systems for amplification and/or attenuation.

The combined current, ie the sum of any current output from the current sources 25a-g, is the current source output. Embodiments may thus act as attenuators and/or amplifiers. There need not be additional circuitry or components between the current sources to combine the current from each current source to provide a usable output current. Therefore, the combined current output on line 27 (shown as b) can be used as desired, for example as an amplifier, an attenuator, to drive a load, etc.

In a preferred embodiment, the current output and magnitude of the current source varies. This provides different weighting of the currents potentially supplied by those current sources. For example, in a preferred embodiment, the first current source is twice the size of the next current source, which in turn is twice the size of the next current source, and so on, until the last current source. The number of current sources can be matched to the number of bits in the digital control word such that the largest current source is controlled by the MSB of the amplitude word, the next largest current source is controlled by the next bit of said word, and so on, until the smallest current source is sent Source LSB. Of course, as noted above, other embodiments may have different patterns of matching bit current sources, including the use of switching networks. Also, in a particularly preferred embodiment, two current sources of the same magnitude are provided, and the magnitude of the current sources varies. In other embodiments, other wave characteristics may be provided to other current sources to adjust those sources.

It should be noted that in the present invention the current source is biased non-linearly. Therefore, any current source works efficiently. Therefore, in a preferred embodiment, power consumption is reduced. In addition, as described above, the resulting output signal has relatively precise linearity and proportionality to the input signal as a result of the current source scaling according to the signal characteristics. Thus, in a preferred embodiment, an amplifier can be provided that has a combination of relative efficiency, relative accuracy, linear operation, and non-linear operation, power consumption.

For example, returning to the embodiment of Fig. 1, if one of the current sources 25a-g is switched on, it will act as a non-linear current source with concomitant relative efficiencies. If multiple current sources are disconnected, the sources consume little or no power. The linearity characteristic appears to be better because each current source turned on provides a current contribution that is similarly proportional to the amplitude characteristic of the input signal, thus providing a relatively accurate reproduction of the input signal.

In the preferred embodiment of Figure 1, current sources 25a-g comprise one or more HBT transistors. Other transistors such as FETs and other current sources may be used. Other components may also be inserted, such as variable gain amplifiers or attenuators for reducing the drive current along the amplitude path to transistor segments, nonlinear components, etc.

Figure 3 depicts another embodiment according to the invention, such as would be used in a transmitter. Driver 516 introduces gain to the carrier signal. Driver 516 is optionally coupled to one or more, preferably multiple, current sources 508 using electric heater 518 . In the bias network B ₀ -B _n−1 , the current source 508 is enabled or disabled according to the bias current provided by the control component 520 . In a preferred embodiment, control component 520 is a conventional switched current source and current source 508 is a transistor. One or more output currents of current sources 508 may be combined and input to load 506 to provide an amplified signal. In this embodiment, any current output from current sources 508 is combined and input to load 506 . If the combined load power is less than the input power, the combined current sources act as attenuators.

Current source 530 in this embodiment maintains a substantially constant DC voltage at node 509 . Also included is an inductor 532 for suppressing, preferably preventing, transient current changes in the current path including the voltage source 530 to drive the load 506 by the current flow from the current source 508 . Capacitor 534 may be provided as DC suppression.

The phase characteristic is modulated by a carrier signal, preferably an RF signal. The modulated carrier signal is used to drive current source 508, preferably simultaneously. A non-linear driver can be used in this embodiment because the carrier signal contains no amplitude information. The output currents from the current sources are then added in order to obtain a substantially linear output signal since, as described above, any currents can be directly combined at node 509 to provide an amplified and/or attenuated signal to drive the load 506 . The added current, or the current output from the current source, can be input directly to the load without additional components such as transformers or quarter-wave transmission lines.

In the embodiment of FIG. 3 , each enabled current source contributes a binary-weighted current to the regulated output signal, and thus to the load, such that current source 508A/2 is twice the current contributed by current source 508A/4 when operating. times, current source 508A/4 contributes twice as much current as current source 508A/8 is operating, etc., but, as should be appreciated, other suitable types of weighting may be used as desired.

In this embodiment, the current sources 508A/2-A/N are enabled or disabled by biasing current into each device, and the control mechanism for selecting the enabled current source is used from the digital control line B ₀ to Bn _-1 represent the digital code generated by the magnitude characteristic. Accordingly, indication signals are input to current sources 508A/2-A/N, thereby enabling or disabling each current source. It should be understood, however, that the control mechanism for the current source may be a bias current generated by a corresponding switched current source, which is provided to a control terminal of the current source, such as the base of a transistor.

According to a preferred embodiment, preferably the amplitude characteristic is digitized. In one embodiment, the peak amplitude is set equal to the full scale of digitization (eg, when all bits are set high) in order to improve linearity. Alternatively, the peak amplitude can be set to a non-digital full scale (eg, larger or smaller). If the peak amplitude is set to be less than full scale, there may be an increase in gain as the average output power level increases for a given power level of the phase modulated carrier signal.

In a related transmitter, use of the preferred embodiments may provide broadband amplitude adjustment capability, since linear amplification and/or attenuation across a relatively large frequency spectrum is possible due to relatively low input capacitance. Accordingly, some embodiments may be used with cellular and other transmitters, as further described herein.

Advantageously, embodiments of the present invention may improve efficiency relative to conventional power amplification, because the linearity of the transfer does not depend on the linearity of the amplifier, but only on how linearly the current increases to the load. Accordingly, each current source can be biased as a non-linear current source, such as class B or C, in order to maximize efficiency. Efficiency can be further increased since there is little or no quiescent current consumption for disabled current sources.

In the illustrated embodiment, power control can be easily achieved since the output current depends primarily on the signal drive level. For example, an increase or decrease in signal drive level using a variable gain amplifier or attenuator results in a corresponding increase or decrease in output current. Additionally, an increase or decrease in bias to the drive controller also results in an increase or decrease in output current, respectively.

It should be understood that any embodiment of the invention may use any suitable type of current source, such as transistor segments and/or formats and other devices or methods, as desired.

In a preferred embodiment, configured as a single integrated circuit, the weighting can be achieved by providing segments with different semiconductor regions. 4A-B show the output characteristics (ie, load lines) of two segments with regions A and A/2, respectively. When the size of the area of a segment is halved, the current supplied to the load through that segment is also halved. This is because the smaller segment has half the current density of the larger segment.

Amplifiers according to embodiments of the present invention may provide a direct digital interface to baseband DSP functions. Amplifiers can also be dynamically scheduled to accommodate multiple modulation formats and wireless network standards. One advantage is that the cost and size of devices using amplifiers according to this aspect of the invention can be reduced. Also, the output current is combined to the load to produce a voltage which may be an analog representation of the amplitude characteristic, so the amplifier also performs digital-to-analog conversion.

Various types of system configurations can be used to construct embodiments of the present invention. Therefore, those of ordinary skill in the art will understand that the embodiments of the present invention, or individual components and/or features thereof, may be entirely composed of hardware, software, or a combination of software and hardware. The embodiments or individual components may also be provided on desired semiconductor components, such as integrated circuits or application specific integrated circuits; some examples include silicon (Si), germanium silicide (SiGe), or gallium arsenide (GaAs) substrates.

Various embodiments may adjust various parameters without departing from the spirit and scope of the present invention. For example, the length of the digital word may be longer or shorter in various embodiments, which may provide more or less precise digitization of the wave. Also for example, as mentioned above, bits, control components, control component lines, driver lines. The bias control lines, current sources, etc. can all be variable as desired.

Although the invention has been described by way of illustrative examples, additional improvements and adaptations will occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details shown and described herein. For example, modifications may be made without departing from the spirit and scope of the invention. Additionally, certain preferred embodiments may include amplifiers dedicated to particular input signals, carrier and output signals, for example, some embodiments may be used with different RF, microprocessor, microcontroller and/or computer devices such as CDMA, CDMA2000 , W-CDMA, GSM, TDMA, etc., and other wired and wireless devices, such as Bluetooth, 802.11a, -b, -g, radar, 1xRTT, two-way radio, GPRS, computers and computer communication equipment, PDAs and others handheld devices, etc. It is intended, therefore, that the present invention not be limited to the specific illustrated embodiments, but be within the full spirit and scope of the appended claims and their equivalents.

Claims (9)

1. An apparatus for electromagnetic processing of an input signal (a), said apparatus comprising: a plurality of independently controllable current sources (25a-g), each current source activated in response to a corresponding one of a plurality of digital amplitude signals, said digital amplitude signal representing an amplitude characteristic of said input signal, when When activated, a plurality of output signals are generated based on an analog phase signal representative of a phase characteristic of said input signal, and said plurality of output signals are directly combined to generate a combined output signal (b). 2. The apparatus for electromagnetic processing of an input signal according to claim 1, said apparatus further comprising: a plurality of control components (22a-g), each control component configured to generate a control signal based on a corresponding one of said digital amplitude signals; Wherein the activation of the plurality of independently controllable current sources is performed through a corresponding one of the control signals. 3. The apparatus for electromagnetic processing of an input signal as claimed in claim 2, wherein each of said plurality of independently controllable current sources is configured to produce a weighted output signal when activated. 4. The apparatus for electromagnetic processing of input signals as claimed in claim 2, wherein: each independently controllable current source of the plurality of independently controllable current sources acts as a non-linear amplifier; each of said plurality of output signals is a weighted non-linear amplification of said analog phase signal; and The combined output signal is a linear amplification of the input signal. 5. The apparatus for electromagnetic processing of input signals as claimed in claim 2, wherein: each of the plurality of independently controllable current sources includes a transistor (508); and each of said transistors is configured to drive said transistor at its base with a pass driver signal; Each of the driver signals includes a combination of the analog phase signal and a corresponding one of the control signals. 6. The apparatus for electromagnetic processing of an input signal as claimed in claim 5, wherein each of said driver signals comprises a current sum of said analog phase signal and a corresponding one of said control signals. 7. The apparatus for electromagnetic processing of an input signal as claimed in claim 2, wherein: The plurality of control components includes N control components; the plurality of independently controllable current sources includes N independently controllable current sources; and The digital amplitude signal includes a plurality of digital words, each digital word includes N bits (B ₀ to B _N-1 ), where B ₀ represents the least significant bit and B _N-1 represents the most significant bit. 8. The apparatus for electromagnetic processing of input signals as claimed in claim 7, wherein An n-th control component of the N control components receives an n-th bit (B _n , 0≤n≤N-1) of the N bits of each digital word of the plurality of digital words; the activation of the nth control component of said N control components depends on the value of the bit (B _n ) it receives; and An nth control component of the N control components is configured to generate a corresponding one of the control signals when activated. 9. The apparatus for electromagnetic processing of an input signal as claimed in claim 8, wherein: An nth independently controllable current source of the plurality of independently controllable current sources is configured to generate an nth weighted output signal ( _in , 0≤n≤N-1); and The nth weighted output signal (i _n ) is weighted equal to i ₀ /2 ⁿ .

Images