CN112468142B - Fractional frequency multiplication injection locking oscillator working method based on multipoint injection technology - Google Patents

Abstract

The invention relates to the technical field of injection locking oscillators, in particular to a fractional frequency multiplication injection locking oscillator working method based on a multipoint injection technology, which comprises the steps of achieving fine change of an equivalent injection position by using a variable-strength and multipoint injection mode, because the multi-point simultaneous injection meets the equivalent vector superposition characteristic, the equivalent injection intensity and injection position are realized by gradually selecting the injection position and changing the proportion of the injection intensity of each point, the fractional frequency multiplication is to be realized, the core of the method is that the current injection position is changed by fraction times of 2 pi radian compared with the last injection position, the method utilizes the characteristic that signals injected at multiple points in the ring oscillator simultaneously meet the vector superposition, the fine change of the position of the injection signal is achieved through the change of the injection position and the strength of the injection signal, and therefore the injection locking oscillator with fractional frequency multiplication capacity is achieved.

Description

A Working Method of Fractional Frequency Multiplication Injection Locked Oscillator Based on Multipoint Injection Technology

technical field

The invention relates to the technical field of injection locking oscillators, in particular to a working method of a fractional frequency doubling injection locking oscillator based on multi-point injection technology.

Background technique

Frequency-doubling structures based on injection-locking technology have been widely used due to their excellent phase noise performance, such as injection-locked oscillators and injection-locked phase-locked loops. However, the injection-locked frequency multiplication structure was only applicable to the integer frequency multiplication of the reference frequency f _REF in the past, that is, the output frequency was N×f _REF (N=1, 2, 3, . . . ), and the output frequency accuracy (ie, the change step size) was Limited to f _REF .

Several techniques are known in the art to attempt to address the above-mentioned problems. Some of these techniques are listed below:

1. By utilizing the polyphase of the ring oscillator, frequency resolution of 1/2 times and 1/4 times f _REF is achieved. (See, eg, the article by S. Lee et al. "Anless inductor injection-locked PLL with 1/2-and 1/4-integral subharmonic locking in 90nm CMOS," in IEEE Radio Frequency integrated Circuits Symposium, 2012, pp. 189-192.

2. This sequential injection locks (SIL) to achieve a frequency resolution of 1/N times _fREF by injecting sequentially at each node around the N-stage ring oscillator. (See P. Park et al., "An all-digital clock generator using a fractionally injection-locked oscillator in 65nm CMOS," in IEEE Int. Solid-State Circuits Conf. Dig. Tech. Papers, 2012, pp. 336-337.

3. Use a sum-and-difference modulator to randomize the delay cells selected for injection, allowing for finer frequency resolution. (See K.-H. Teng et al., "A 370-pJ/b multichannel BFSK/QPSK transmitter using injection-locked fractional-N synthesizer for wireless biotelemetry devices," IEEE J. Solid-State Circuits, vol. 52, no. 6, pp. 867–880, Mar. 2017.

In 3, there is a high frequency shaped quantization phase noise problem in the sequential injection locking structure based on sum-difference modulators. These techniques are trying to solve this problem:

4. After using the sum-difference modulator, reduce the quantization phase noise of high frequency shaping by increasing the frequency of the injected signal and reducing the intensity of the injected signal. (See W. Deng et al. "A 0.048mm ² 3mW synthesizable fractional-N PLL with a soft injection-locking technique," in IEEE Int. Solid-State Circuits Conf. Dig. Tech. Papers, 2015, pp. 252-253.

5. By adding a phase-locked loop (PLL) at the next stage after using the sum-difference modulator. (See X. Meng et al. "Alow-noise digital-to-frequency converter based on injection-lockedringoscillator and rotated phase selection for fractional-Nfrequency synthesis," IEEE Trans. on Very Large Scale Integration (VLSI) Systems, vol. 27, no. 6, pp.1578–1389, Jun. 2019.

Traditional injection-locked oscillators can only achieve integer frequency multiplication, and the output frequency accuracy is limited. To achieve fractional frequency doubling, the technique described in the second item 2 can be used. This sequential injection locking approach can achieve a frequency resolution of 1/N times _fREF . But in order to obtain better resolution, the number of delay cell stages must be increased. And the expression considering the output frequency is:

Among them, T _inv is the delay time of the single-stage delay unit, so the increase of N will lead to the reduction of the output frequency, and the increase of the number of stages will lead to the increase of power consumption, which cannot meet the actual needs;

When using the technique described in the second item 3, the sum-difference modulator introduces additional shaping and quantization noise, significantly degrading the noise performance at high frequency offsets of the output signal;

While 4 and 5 of the second term try to address the high frequency quantization noise introduced by the sum-difference modulator, 4 sacrifices noise performance, and 5 may produce folded phase noise or fractional spurs due to charge pump imperfections.

The multi-point injection technology with programmable strength proposed by the present invention can even achieve higher frequency resolution without using a sum-difference modulator, avoiding the above problems.

The present invention aims to break through the limitation of the number of oscillator stages on the precision of the output frequency without using the sum-difference modulator. Using the feature that the injected signal will be superimposed on a vector, and using the multi-point injection technique, it is equivalent to realize the fine change of the injection position. As a result, a higher target frequency, high-precision frequency resolution, and excellent phase noise performance can be obtained.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the problems existing in the prior art, and to provide a working method of a fractional frequency doubling injection-locked oscillator based on the multi-point injection technology, which can solve the problems of the prior art at least to a certain extent.

In order to realize the above-mentioned technical purpose and achieve the above-mentioned technical effect, the present invention is achieved through the following technical solutions:

A working method of a fractional-frequency injection-locked oscillator based on multi-point injection technology, comprising the following steps:

Step 1) Use the method of variable intensity and multi-point injection to achieve fine changes in the equivalent injection position. Since the signals injected at the same time at multiple points meet the equivalent vector superposition characteristics in the oscillator, by gradually selecting the injection position and changing the injection point at each point. The magnitude and ratio of the intensity, so as to achieve the required implant intensity and implant location equivalently;

Step 2) Based on the vector superposition characteristic satisfied by the multi-point injection in step 1), to realize the fine change of the equivalent injection position and the constant equivalent injection intensity, to achieve fractional frequency multiplication in the sequential injection-locked oscillator, its The core is that the current injection position has changed by 2π radians compared with the last injection position. To improve the output frequency accuracy by M times without increasing the number of ring oscillator series N, the effect that needs to be achieved is to make the position of each injection. Compared with the previous injection, the phase shift is 2π/(M×N);

Step 3) Realize the digital controllability of the intensity of the injected signal, and use the number of gated injection transistors in the pseudo-differential oscillation unit to adjust the intensity of the injection, so that each time the described injection is realized, the injection intensity is changed by an integer multiple of units compared to the previous injection. Intensity, by cascading N-stage delay units, inserting M injection tubes between every two delay stages, and each injection tube is selected to access the injection signal or completely shut down through a two-choice data selector, so as to achieve each Level injection strength M+1 level adjustable;

Step 4) Use the circuit structure of the digital programmable mode to determine the injection position and the injection intensity corresponding to the injection position, the circuit includes multiple sets of counters, pulse circuit generators, multiple multiplex output selectors, binary code to thermometer code conversion The working method specifically includes the following contents:

Step 4.1. Pass the reference clock signal f _REF through the a-bit accumulator, and the accumulator performs an accumulation at each rising edge time. The accumulated result x corresponds to the injection strength of the second point when the two points are injected, and the injection strength of the first point is 2 ^a -x, that is, the injection strength of each point is 2 ^a +1 level adjustable, and the total injection strength of the two points is always 2 ^a , the output of the accumulator is decoded after passing through a multiplexer, and the selected The number of pass injection transistors;

Step 4.2, the reference clock signal f _REF is generated by the pulse generation module to generate a pulse signal with a period consistent with the reference source signal and a certain pulse width, which is used as an injection signal, and is output to the phase to be injected through a multiplexer output selector;

Step 4.3, take the overflow signal of the a-bit accumulator as the counting signal of the b-bit counter, and add 1 to the counting result of the b-bit counter whenever the a-bit accumulator overflows;

Step 4.4. Use the count result of the b-bit counter as an address signal to access the multiplexer. The count result of the counter corresponds to the two adjacent phases currently injected, that is, with each overflow of the a-bit accumulator, the injected position It will change from Φ ₀ , Φ ₁ to Φ ₁ , Φ ₂ , from Φ ₁ , Φ ₂ to Φ ₂ , Φ ₃ , ..., from Φ _N-2 , Φ _N-1 to Φ _N-1 , Φ ₀ , to achieve the effect of sequential injection locking;

Step 4.5. To realize the injection-locked frequency multiplier with the minimum frequency resolution, the injection position and injection intensity are as follows: 2 ^a +1 injection pipes are gated at Φ ₀ , 0 injection pipes are gated at Φ ₁ → Φ Gating 2 ^a injection pipe at ₀ , gating 1 injection pipe at Φ ₁ → Gating 2 ^a at Φ ₀ -1 injection pipe, gating 2 injection pipes at Φ ₁ →...→Selecting at Φ ₀ 1 injection pipe, 2 ^a injection pipe at Φ ₁ → 0 injection pipes at Φ ₀ , 2 ^a +1 injection pipe at Φ ₁ , 0 injection pipes at Φ ₂ → ^2a injection pipes are gated at Φ ₁ , and 1 injection pipe is gated at Φ ₂ →…;

Among them, each "→" represents a rising edge of f _REF ,

Periodically repeating the above injection sequence, the minimum frequency resolution can be achieved as

Further, in the step 3), when the injection strength is changed by the number of gated injection transistors, the specific content includes the following: a single-ended delay unit with independently programmable injection strength is used, Str<1>...Str<M> is used as a selection signal to determine whether the injection signal I _nj enters through the data selector of two options. When Str=1, it indicates that the injection behavior of the transistor occurs. At the same time, the number of thermometer codes of 1 also determines the intensity of injection. Assuming that the number of Str<1>...Str<Μ> equal to 1 is n, the injection intensity is n.

The beneficial effects of the present invention are as follows: the signals injected simultaneously at multiple points in the ring oscillator satisfy the characteristics of vector superposition, and through the changes of the injection position and the intensity of the injected signal, the fine change of the position of the injected signal is achieved, thereby realizing a fractional multiplication ratio. frequency-capable injection-locked oscillator, the specific benefits are as follows:

1. In the structure that does not use the delta-sigma modulator (DSM, delta-sigma modulator), the output frequency accuracy of the existing structure depends on the number of oscillator stages, but when the number of stages is increased to improve the output accuracy, the oscillator will be reduced. the oscillation frequency;

2. When the sum-difference modulator is used to achieve good output accuracy, shaping and quantization noise will be introduced, which will significantly deteriorate the noise performance at the high-frequency offset of the output signal;

3. The present invention utilizes the feature of vector superposition of injected signals, and uses multi-point injection technology to achieve fine changes in the injection position. Without using a sum-difference modulator, it breaks through the limit of the oscillator series on the output frequency accuracy. , so that a higher target frequency, high-precision frequency resolution can be obtained, while maintaining excellent phase noise performance.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of a conventional sequential injection-locked ring oscillator and a sequential injection-locked ring oscillator based on a sum-difference modulator;

Fig. 2(a) is a schematic diagram of injection position change in conventional sequential injection locking; Fig. 2(b) is a schematic diagram of injection position change in sequential injection locking based on sum-difference modulator;

3 is a schematic diagram of applying multi-point (two-point) injection locking technology in a ring oscillator;

FIG. 4 is a schematic diagram of realizing the fine variation of the equivalent injection position in a 2-stage differential ring oscillator by a multi-point (two-point) injection technique;

FIG. 5 is a schematic structural diagram of a delay cell with independently programmable injection strength according to an embodiment of the present invention;

6 is a schematic diagram for implementing a multi-point, variable-strength injection-locked ring oscillator in an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a control circuit for determining the injection position and the injection strength corresponding to the injection position in an embodiment of the present invention.

Detailed ways

In order to make the technical means, creative features, goals and effects realized by the present invention easy to understand, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. The described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

A working method of a fractional-frequency injection-locked oscillator based on multi-point injection technology, comprising the following steps:

Step 1) Use the method of variable intensity and multi-point injection to achieve fine changes in the equivalent injection position. Since the signals injected at the same time at multiple points meet the equivalent vector superposition characteristics in the oscillator, by gradually selecting the injection position and changing the injection point at each point. The magnitude and ratio of the intensity, so as to achieve the required implant intensity and implant location equivalently;

Step 2) Based on the vector superposition characteristic satisfied by the multi-point injection in step 1), to realize the fine change of the equivalent injection position and the constant equivalent injection intensity, to achieve fractional frequency multiplication in the sequential injection-locked oscillator, its The core is that the current injection position has changed by 2π radians compared with the last injection position. To improve the output frequency accuracy by M times without increasing the number of ring oscillator series N, the effect that needs to be achieved is to make the position of each injection. Compared with the previous injection, the phase shift is 2π/(M×N);

Step 3) Realize the digital controllability of the injection signal strength, and use the gated injection transistor number in the pseudo-differential oscillation unit to adjust the injection strength, so as to realize the above-described injection in which the unit strength is changed over the previous injection during each injection. The intensity is changed by an integer multiple of the unit intensity. By cascading N-stage delay units, M injection tubes are inserted between every two delay stages, and each injection tube is selected to access the injection signal or Completely shut off, and then achieve adjustable injection intensity M+1 level for each level;

Step 4) Use the circuit structure of the digital programmable mode to determine the injection position and the injection intensity corresponding to the injection position, the circuit includes multiple sets of counters, pulse circuit generators, multiple multiplex output selectors, binary code to thermometer code conversion The working method specifically includes the following contents:

Step 4.1. Pass the reference clock signal f _REF through the a-bit accumulator, and the accumulator performs an accumulation at each rising edge time. The accumulated result x corresponds to the injection strength of the second point when the two points are injected, and the injection strength of the first point is 2 ^a -x, that is, the injection strength of each point is 2 ^a +1 level adjustable, and the total injection strength of the two points is always 2 ^a , the output of the accumulator is decoded after passing through a multiplexer, and the selected The number of pass injection transistors;

Step 4.2, use the reference clock signal f _REF to generate a pulse signal with a certain pulse width and period consistent with the reference source signal through the pulse generation module, use it as an injection signal, and output it to the phase to be injected through a multiplexer output selector;

Step 4.3, take the overflow signal of the a-bit accumulator as the counting signal of the b-bit counter, and add 1 to the counting result of the b-bit counter whenever the a-bit accumulator overflows;

Step 4.4. Use the count result of the b-bit counter as an address signal to access the multiplexer. The count result of the counter corresponds to the two adjacent phases currently injected, that is, with each overflow of the a-bit accumulator, the injected position It will change from Φ ₀ , Φ ₁ to Φ ₁ , Φ ₂ , from Φ ₁ , Φ ₂ to Φ ₂ , Φ ₃ , ..., from Φ _N-2 , Φ _N-1 to Φ _N-1 , Φ ₀ , to achieve the effect of sequential injection locking;

Step 4.5. To realize the injection-locked frequency multiplier with the minimum frequency resolution, the injection position and injection intensity are as follows: 2 ^a +1 injection pipes are gated at Φ ₀ , 0 injection pipes are gated at Φ ₁ → Φ Gating 2 ^a injection pipe at ₀ , gating 1 injection pipe at Φ ₁ → Gating 2 ^a at Φ ₀ -1 injection pipe, gating 2 injection pipes at Φ ₁ →...→Selecting at Φ ₀ 1 injection pipe, 2 ^a injection pipe at Φ ₁ → 0 injection pipes at Φ ₀ , 2 ^a +1 injection pipe at Φ ₁ , 0 injection pipes at Φ ₂ ( At this time, the a-bit accumulator overflows once) → 2 ^a injection pipes are gated at Φ ₁ , and 1 injection pipe is gated at Φ ₂ →...;

Among them, each "→" represents a rising edge of f _REF ,

Periodically repeating the above injection sequence, the minimum frequency resolution can be achieved as

Further, in the step 3), when the injection strength is changed by the number of gated injection transistors, the specific content includes the following: a single-ended delay unit with independently programmable injection strength is used, Str<1>...Str<M> is used as a selection signal to determine whether the injection signal I _nj enters through the data selector of two options. When Str=1, it indicates that the injection behavior of the transistor occurs. At the same time, the number of thermometer codes of 1 also determines the intensity of injection. Assuming that the number of Str<1>...Str<Μ> equal to 1 is n, the injection intensity is n.

In Fig. 1, when the input of the accumulator is 1, the overall structure is a conventional sequential injection-locked ring oscillator. - For an N-level ring oscillator, the variation of each injection position is 2π/N, and after N reference source cycles, the 2π radian chase is completed, so the output frequency accuracy is 1/N times the reference source frequency;

In Fig. 1, when the input of the accumulator is the output of ΔΣM, the overall structure is a sequential injection-locked ring oscillator based on the sum-difference modulator. The injection position is changed by α phases compared to the previous injection - for an N-stage ring oscillator, the change in the injection position is 2πα/N each time, and the 2π radian catch-up is completed after N/α reference source cycles , so the output frequency accuracy is α/N times the reference source frequency;

However, because the sum-difference modulator achieves the purpose of averaging α by controlling the number of output 0s and 1s, rather than the real output of the decimal α, the problem of quantization noise will be introduced.

Figure 3 is a schematic diagram of applying multi-point (two-point) injection locking technology in a ring oscillator. When two injection signals exist at the same time, the injection position and injection strength of the equivalent injection signal are superimposed by the vector of the actual two injection signals obtained;

Figure 4 is a schematic diagram of realizing the fine change of the equivalent injection position in the 2-stage differential ring oscillator through the multi-point (two-point) injection technology - by changing the injection signal strength of two adjacent points and selecting two injection points sequentially, The position of each injection can be changed to 1/3 of the phase compared to the previous injection, and the output accuracy of 1/12 of the reference source frequency can be achieved. If conventional sequential injection locking is used, the accuracy is only 1/4 of the reference source frequency;

5 is a schematic structural diagram of a delay cell with independently programmable injection strength according to an embodiment of the present invention, the injection strength of which is determined by the number of selected pass-through injection transistors, so the change of the injection strength is linearly controllable;

6 is a schematic diagram for implementing a multi-point, variable-strength injection-locked ring oscillator in an embodiment of the present invention, wherein the structure of the delay unit is the same as that in FIG. 5 , and the schematic diagram selects 8 levels of differential (16 phases) and 8 levels of injection strength. It can achieve the output frequency accuracy of 1/(16×8) times the reference source frequency - the number of phases and the number of injection intensity files can be adjusted according to the actual application;

7 is a schematic structural diagram of a control circuit for determining the injection position and the injection intensity corresponding to the injection position in an embodiment of the present invention, wherein the number of bits of the accumulator is determined by the number of injection intensity levels, and the number of bits of the counter is determined by the number of phases of the ring oscillator .

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in a process, method, article or apparatus that includes the element.

The above-disclosed preferred embodiments of the present invention are provided only to help illustrate the present invention. The preferred embodiments do not exhaust all the details, nor do they limit the invention to only the described embodiments. Obviously, many modifications and variations are possible in light of the content of this specification. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is to be limited only by the claims and their full scope and equivalents.

Claims (2)

1. A fractional frequency multiplication injection locking oscillator working method based on a multipoint injection technology is characterized by comprising the following steps:

step 1) achieving fine change of equivalent injection positions by using a variable-strength and multi-point injection mode, wherein due to the fact that signals injected at the same time at multiple points meet equivalent vector superposition characteristics in an oscillator, required injection strength and injection positions are equivalently achieved by gradually selecting injection positions and changing the injection strength of each point;

step 2) based on the vector superposition characteristic satisfied by multipoint injection in step 1), realizing fine change of an equivalent injection position and equivalent injection strength which is kept unchanged, and realizing fractional frequency multiplication in a sequential injection locked oscillator, wherein the core of the method is that the current injection position generates 2 pi radian change compared with the last injection position, the output frequency precision is improved by M times under the condition of not increasing the stage number N of the ring oscillator, and the effect required to be achieved is to ensure that the phase shift of each injection position compared with the previous injection position is 2 pi/(M x N);

step 3) realizing the digital controllability of the intensity of the injection signal, utilizing the number of gating injection transistors to adjust the injection intensity in a pseudo-differential oscillation unit, changing the injection intensity by integral multiple unit intensity compared with the injection intensity of the last time when realizing the described each injection, cascading N stages of delay units, inserting M injection pipes between every two delay stages, and selectively accessing or completely shutting off the injection signal by an alternative data selector for each injection pipe so as to achieve the adjustability of each injection intensity M +1 stage;

step 4) determining the injection position and the injection intensity corresponding to the injection position by using a circuit structure of a digital programmable mode, wherein the circuit comprises a plurality of groups of counters, a pulse circuit generator, a plurality of multipath output selectors and a binary code to thermometer code converter circuit, and the working method specifically comprises the following contents:

step 4.1, reference clock signal f _REF The accumulator carries out accumulation once at each rising edge moment through the a-bit accumulator, the accumulated result x corresponds to the injection intensity of the second point when two points are injected, and the injection intensity of the first point is 2 ^a X, i.e. the injection intensity per point is 2 ^a The +1 level is adjustable, and the total injection intensity of two points is always 2 ^a The output of the accumulator is decoded after passing through a multi-path output selector, and the number of the injection transistors is gated;

step 4.2, reference clock signal f _REF Generating a pulse signal with a period consistent with that of a reference source signal and a certain pulse width through a pulse generating module, using the pulse signal as an injection signal, and outputting the pulse signal to a phase to be injected through a multi-path output selector;

step 4.3, taking an overflow signal of the a-bit accumulator as a counting signal of the b-bit counter, and adding 1 to a counting result of the b-bit counter every time the a-bit accumulator overflows;

step 4.4, the counting result of the b-bit counter is accessed into the multi-path output selector as an address signal, the counting result of the counter corresponds to two adjacent phases of the current injection, namely, the injection position can be from phi along with each overflow of the a-bit accumulator ₀ 、Φ ₁ Becomes phi ₁ 、Φ ₂ From Φ ₁ 、Φ ₂ Becomes phi ₂ 、Φ ₃ … …, from Φ _N-2 、Φ _N-1 Becomes phi _N-1 、Φ ₀ Achieving the effect of sequential injection locking;

step 4.5, if the injection locking frequency multiplier with the minimum frequency resolution is to be realized, the injection position and the injection intensity are as follows in sequence: phi ₀ Place strobe 2 ^a +1 injection tubes, phi ₁ Gate 0 injection tubes → phi ₀ Place strobe 2 ^a A filling pipe phi ₁ Gate 1 injection tube → phi ₀ Place strobe 2 ^a -1 injection tube,. phi ₁ Gate 2 injection tubes → … … → phi ₀ Gate 1 injection tube, phi ₁ Place strobe 2 ^a Injection tube → phi ₀ Gate 0 injection tubes phi ₁ Place strobe 2 ^a +1 injection tubes, phi ₂ Gate 0 injection tubes → phi ₁ Place strobe 2 ^a A filling pipe phi ₂ Gate 1 injection tube → … …;

wherein each "→" represents one time f _REF The rising edge of (a) of (b),

the injection sequence is periodically and circularly carried out, so that the minimum frequency resolution is realized

2. The operating method of fractional frequency doubling injection locked oscillator based on multi-point injection technology according to claim 1, wherein in the step 3), when the injection strength is changed by using the number of gated injection transistors, the method specifically includes the following steps: using single-ended delay cells with independently programmable injection strengths Str < 1 > … Str < M > as selection signals through an alternative data selector to determine injection signal I _nj If Str is equal to 1, the transistor injection behavior is indicated, and the number of thermometer codes 1 also determines the injection strength, and if the number of Str < 1 > … Str < M > is equal to 1, the injection strength is n.

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