CN1705233B - Injection-locked frequency division circuit and its frequency division method - Google Patents

Abstract

An injection-locked frequency division circuit includes a selection module for generating a control signal; a bias module coupled to the selection module for receiving an original signal to generate a bias signal according to the control signal; and an oscillation module coupled to the bias module for receiving the bias signal to generate a target signal; wherein the frequency of the target signal has a ratio relationship with the frequency of the original signal.

Description

Injection-locked frequency division circuit and its frequency division method

technical field

The invention relates to a frequency division circuit and its frequency division method, in particular to an injection-locked frequency division circuit and its frequency division method which expands the bandwidth by controlling the bias current.

Background technique

The frequency divider is a very important part of the frequency synthesizer (frequency synthesizer), which is used to divide an original pulse wave to generate a target pulse wave, wherein the frequency of the target pulse wave is the same as the original pulse wave The frequency of the wave is corresponding to a frequency division ratio. As is well known in the industry, traditionally a frequency division circuit is formed by a plurality of frequency division units connected in series (cascade), in which a flip-flop is often used as its main component, but due to the flip-flop ) itself is a digital element, which is generally driven by a preset low voltage (such as 0V) and a preset high voltage (such as 5V). Therefore, for each flip-flop in the frequency division circuit, It needs to consume a lot of power when charging and discharging. Therefore, when the operating frequency is high, the power consumption of the traditional frequency division circuit also increases.

Therefore, injection-locked frequency divider (injection-locked frequency divider) came into being, such as Rategh et al. in "Superharmonic Injection-Locked Frequency Dividers", IEEE Journal of Solid-State Circuits, Vol.34, No.6, June As described in 1999, the injection-locked frequency division circuit is an analog frequency division circuit, which directly processes the original analog signal transmitted and outputs a frequency-divided analog signal. Generally, an injection-locked frequency division circuit is composed of an oscillation module and a bias voltage module. The bias voltage module is used to receive the original signal to be frequency-divided transmitted by the previous stage circuit (such as the voltage-controlled oscillator in the frequency synthesizer), and inject it into the oscillation module. After the injection-locked frequency division circuit is properly designed, the frequency-divided target signal can be extracted from the oscillation module, wherein the oscillation frequency of the target signal and the oscillation frequency of the original signal are locked to a specific frequency division. The frequency ratio depends on the circuit characteristics.

Although the injection-locked frequency division circuit has the advantages of operating at high frequencies and can directly process analog signals to save power consumption, the circuit design of the injection-locked frequency division circuit must properly match the oscillation frequency and oscillation of the original signal. Only the oscillation frequency of the module (that is, its center frequency) can normally perform the frequency division operation, so the working bandwidth of the injection-locked frequency division circuit is usually quite narrow.

Contents of the invention

Therefore, the main purpose of the present invention is to provide an injection-locked frequency division circuit and a frequency division method thereof for enlarging the bandwidth by controlling the bias current.

According to an embodiment of the present invention, an injection-locked frequency division circuit is disclosed, which includes a selection module for generating a control signal; a bias module coupled to the selection module for receiving an original signal, to generate a bias signal according to the control signal; and an oscillation module, coupled to the bias module, for receiving the bias signal to generate a target signal; wherein the frequency of the target signal is different from the frequency of the original signal There is a ratio relationship between them.

According to an embodiment of the present invention, a frequency division method is also disclosed, which includes inputting an original signal; inputting a control signal; using a bias module to generate a bias signal according to the original signal and the control signal; using a The oscillation module generates a target signal according to the bias signal; and changes the control signal to change the frequency of the target signal, wherein the frequency of the target signal has a ratio relationship with the frequency of the original signal.

Description of drawings

FIG. 1 is a schematic diagram of an injection-locked frequency division circuit according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an injection-locked frequency division circuit according to another embodiment of the present invention.

FIG. 3 is a schematic diagram of an injection-locked frequency division circuit according to another embodiment of the present invention.

Explanation of reference symbols:

50, 50', 50" frequency division circuit

60, 60', 60" Oscillator Module

70, 70a, 70b, 70c, 70d, 70e Bias Module

80 input signal sources

90 selection modules

92 bias voltage generator.

Detailed ways

Please refer to FIG. 1 . FIG. 1 is a schematic diagram of a divided-by-3 injection-locked frequency divider circuit (injection-locked frequency divider) 50 according to an embodiment of the present invention. In this embodiment, the injection-locked frequency division circuit 50 includes an oscillation module 60 , a bias voltage module 70 , and a selection module 90 . The bias module 70 is used to receive an original signal from an input signal source 80 (which may be a voltage-controlled oscillator of a frequency synthesizer or other signal sources that require frequency division) and inject current according to the original signal. to the oscillation module 60, so that the frequency-divided target signal is generated in the oscillation module 60, wherein the oscillation frequency of the target signal and the oscillation frequency of the original signal are locked at a specific frequency division ratio, and the frequency division ratio depends on circuit characteristics. In addition, the bias module 70 also determines the amount of bias current injected into the oscillation module 60 according to the control signal transmitted from the selection module 90 . As is widely known to those skilled in the art, since the oscillation frequency of the oscillation module 60 can be determined by the input bias current, the operation of the injection-locked frequency division circuit 50 can be adjusted by the above-mentioned control mechanism. frequency band. In this way, the injection-locked frequency division circuit 50 of this embodiment can have a larger operating bandwidth.

In this embodiment, the oscillator 60 is a ring oscillator (ring oscillator) composed of three inverters. The configuration and operating principle of the ring oscillator are widely known to those skilled in the art. So I won't go into details here. The bias module 70 includes a plurality of sub-bias modules 70a, 70b, 70c, 70d, and 70e, which are respectively coupled to a current source IB and an electrical chip through the electrical chips M12, M13, M14, M15, and M16. The bias current generator 92 composed of M11 respectively forms a plurality of current mirror configurations (current mirror configuration), so as to replicate a bias voltage on each sub-bias module 70a, 70b, 70c, 70d, 70e current. And each sub-bias module 70a, 70b, 70c, 70d, 70e also includes a control switch (electric chip M17, M18, M19, M20, M21 as shown in Figure 1), which is controlled by the selection module 90 respectively. Signals C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ are used to control their opening and closing, that is, when a control switch is in an on state, its corresponding sub-bias module is in an enabled state. In this way, the selection module 90 can control the amount of bias current injected into the oscillation module 60 through different combinations of the generated control signals C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ , so as to further control injection locking. The frequency division circuit 50 performs a frequency division operation on the original signal input from the input signal source 80 . In other words, the selection module 90 can change the combination of the control signals C ₁ , C ₂ , C ₃ , C ₄ , and C ₅ to change the oscillation frequency of the target signal, and further change the operating frequency band of the injection-locked frequency division circuit 50 .

In this embodiment, since the oscillating module 60 is a ring oscillator composed of three inverters, the difference between the oscillation frequency of the original signal generated by the input signal source 80 and the target signal taken out by the oscillating module 60 is The frequency division ratio between is 3:1, that is to say, the oscillating frequencies of the signals on the input terminal A and the output terminal B in FIG. 1 will have a specific proportional relationship of 3:1. As mentioned above, since the oscillation frequency of the oscillation module 60 can be determined by the amount of bias current input, when the amount of bias current injected into the oscillation module 60 is controlled by the selection module 90 to different sizes, the oscillation frequency of the oscillator 60 The center frequency will have different values accordingly, and then the injection-locked frequency division circuit 50 can be used for frequency division of original signals with different oscillation frequencies, that is to say, the injection-locked frequency division circuit 50 of this embodiment It can have a larger operating bandwidth with the assistance of the sub-bias modules 70a, 70b, 70c, 70d, 70e.

The electrical chips M12, M13, M14, M15, M16 used to form the current mirror in the sub-bias modules 70a, 70b, 70c, 70d, 70e can have the same element characteristics, such as corresponding to the same channel width/length ratio (W/ L ratio, aspect ratio), so the selection module 90 can achieve the purpose of controlling the bias current by controlling the number of sub-bias modules 70a, 70b, 70c, 70d, and 70e turned on. However, the electrical chips M12, M13, M14, M15, and M16 used to form the current mirror in the sub-bias modules 70a, 70b, 70c, 70d, and 70e may also have different element characteristics, such as corresponding to different channel width/length ratios For example, the channel width/length ratio of the electronic chips M12, M13, M14, M15, M16 can have the following ratio: 1:2:4:8:16, so that more control signals can be combined to achieve more Wide range of operating bandwidth. Please note that only five bias modules 70a, 70b, 70c, 70d, and 70e are shown in FIG. 1 for illustration. However, the injection-locked frequency dividing circuit 50 of the present invention does not limit the number of sub-bias modules.

Please refer to FIG. 2 , which shows a schematic diagram of a divided-by-4 injection-locked frequency dividing circuit 50 ′ according to an embodiment of the present invention. The injection-locked frequency division circuit 50' in FIG. 2 is very similar to the injection-locked frequency division circuit 50 in FIG. 1, but the oscillation module 60' in FIG. 2 uses a differential mode ring oscillator, The circuit configuration and operation method of the differential ring oscillator are widely known to those skilled in the art, so they will not be repeated here. The operation principle of the injection-locked frequency division circuit 50 ′ in FIG. 2 is the same as that of the injection-locked frequency division circuit 50 in FIG. 1 , so the description will not be repeated.

Please refer to FIG. 3 , which shows an embodiment of the present invention divided by two (divided-by-2) injection-locked frequency division circuit 50 "schematic diagram. Injection-locked frequency division circuit 50 " in Fig. 3 and Fig. 1 The injection-locked frequency division circuit 50 is very similar to the one shown in FIG. It is widely known by those skilled in the art, so it will not be repeated here. And the operation principle of the injection-locked frequency division circuit 50 "in Fig. 3 is the same as that of the injection-locked frequency division circuit 50 in Fig. 1, so it will not be repeated illustrate.

The above descriptions are only preferred embodiments of the present invention, and all equivalent changes and modifications made according to the claims of the present invention shall fall within the scope of the patent of the present invention.

Claims (9)

1. An injection-locked frequency division circuit, comprising: a selection module, used to generate a control signal; a bias module, coupled to the selection module, used to receive an original signal to generate a bias signal according to the control signal; and An oscillation module, coupled to the bias module, is used to receive the bias signal to generate a target signal; There is a ratio relationship between the frequency of the target signal and the frequency of the original signal. 2. The injection-locked frequency dividing circuit as claimed in claim 1, wherein the bias module controls the bias current of the bias signal according to the control signal. 3. The injection-locked frequency division circuit as claimed in claim 1, wherein the selection module changes the control signal to change the operating frequency band of the injection-locked frequency division circuit. 4. The injection-locked frequency dividing circuit as claimed in claim 1, wherein the bias module further comprises a plurality of sub-bias modules. 5. The injection-locked frequency division circuit as claimed in claim 4, wherein each sub-bias module comprises: a current source for providing a current signal; and A switch, coupled to the current source, is used for switching on and off according to the control signal. 6. The injection-locked frequency division circuit as claimed in claim 1, wherein the oscillation module is a ring oscillator, or a differential ring oscillator, or an LC cavity oscillator. 7. A frequency division method, which includes: input an original signal; input a control signal; using a bias module to generate a bias signal according to the original signal and the control signal; using an oscillating module to generate a target signal according to the bias signal; and changing the control signal to change the frequency of the target signal, There is a ratio relationship between the frequency of the target signal and the frequency of the original signal. 8. The frequency dividing method as claimed in claim 7, wherein the step of generating the bias signal comprises: controlling a bias current of the bias signal according to the control signal. 9. The frequency dividing method as claimed in claim 7, wherein the step of generating the bias signal comprises: controlling the enabled states of a plurality of sub-bias modules according to the control signal.

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