An automatic bandwidth compensation circuit based on phase detection

Abstract

The application discloses an automatic bandwidth compensation circuit based on phase detection, which comprises a signal main link, a signal copy link, a phase detector, a first amplifier, an amplitude discriminator and a second amplifier. The application can automatically adjust the bandwidth compensation of the signal main link by detecting the phase deviation of the data signals at the output ends of the signal main link and the signal copy link, can guarantee the consistency of the bandwidth and the delay of the circuit under different gains, and can avoid large-scale temperature compensation of the circuit and the super-high design difficulty caused by the sudden change of the device characteristics.

Description

Technical Field

[0001] This invention relates to the field of bandwidth compensation circuit design technology, and specifically to an automatic bandwidth compensation circuit based on phase detection. Background Technology

[0002] In high-frequency circuits, parasitics can reduce the circuit's bandwidth, necessitating bandwidth compensation to maintain high-frequency characteristics. In typical fixed-gain circuits, simply matching the compensation capacitor value to the circuit's specifications yields a good performance. However, in variable-gain amplifiers, gain variations can cause a mismatch between the compensation capacitor and the circuit, leading to either undercompensation or overcompensation. In such cases, adjusting the circuit's compensation characteristics is required.

[0003] Current variable gain amplifiers use a feedforward method to compensate for circuit bandwidth, and the main problems and drawbacks include the following:

[0004] A. The compensation signal needs to be compensated twice to prevent insufficient or excessive bandwidth compensation caused by changes in device and circuit characteristics due to factors such as temperature.

[0005] B. The changes in the device are not linear, resulting in low consistency of compensation effect within the operating range. Summary of the Invention

[0006] To address the aforementioned shortcomings in the prior art, the present invention provides an automatic bandwidth compensation circuit based on phase detection.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0008] An automatic bandwidth compensation circuit based on phase detection includes:

[0009] The main signal link, the signal replication link, the phase detector, and the first amplifier;

[0010] The input terminal of the main signal link receives a data signal and a gain control signal, and the output terminal of the main signal link outputs a data signal and is connected to the input terminal of the phase detector.

[0011] The input end of the signal replication link is connected to the input end of the main signal link, and its output end is connected to the input end of the phase detector.

[0012] The output of the phase detector is connected to the input of the first amplifier, and the output of the first amplifier is connected to the bandwidth compensation control terminal of the main signal link.

[0013] The beneficial effects of this solution are: This invention automatically adjusts the bandwidth compensation of the main signal link by detecting the phase deviation of the data signal at the output end of the main signal link and the signal replication link through a phase detector. This can ensure the consistency of the bandwidth and delay of the circuit under different gain conditions, and avoid large-scale temperature compensation of the circuit, thus avoiding the extremely high design difficulty caused by sudden changes in device characteristics.

[0014] Furthermore, the main signal link includes an N-stage amplifier link, where N ≥ 1.

[0015] The beneficial effect of this further solution is that signal transmission amplification has certain requirements for gain, and there are often situations where the gain and bandwidth of a single amplification stage cannot be simultaneously achieved. Therefore, this invention increases the number of stages according to the requirements and reduces the gain of a single amplification stage, so as to effectively improve the maximum bandwidth achievable by the circuit design.

[0016] Furthermore, the signal replication link includes an amplifier link with the same number of stages as the main signal link.

[0017] The beneficial effect of this further solution is that the core of this invention lies in ensuring that the main signal link and the signal replication link have the same number and location of zeros and poles, so as to guarantee that the amplitude-frequency attenuation characteristics of the two circuits are exactly the same. The number of stages in the signal replication link must be the same as the number of stages in the main signal link to ensure that the main signal link and the signal replication link have the same number of zeros and poles.

[0018] Furthermore, the first amplifier is a low-pass filter amplifier.

[0019] The beneficial effect of this further solution is that the present invention filters the signal through a low-pass filter amplifier to obtain a stable detection result, thereby enabling the circuit to operate stably.

[0020] Furthermore, the circuit also includes an amplitude discrimination circuit and a second amplifier;

[0021] The input terminal of the amplitude discrimination circuit is connected to the output terminal of the signal replication link, and its output terminal is connected to the input terminal of the second amplifier. The output terminal of the second amplifier is connected to the bandwidth compensation control terminal of the signal replication link.

[0022] The beneficial effect of this further solution is that the present invention identifies the output signal amplitude of the signal replication link through an amplitude discrimination circuit. When the output signal amplitude of the signal replication link is limited, the bandwidth characteristics of the signal replication link are adjusted so that the transmission characteristics of the signal replication link are more consistent before and after the limiting.

[0023] Furthermore, the second amplifier is a low-pass filter amplifier.

[0024] The beneficial effect of this further solution is that the present invention filters the signal through a low-pass filter amplifier to obtain a stable detection result, thereby enabling the circuit to operate stably. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the automatic bandwidth compensation circuit structure based on phase detection of the present invention;

[0026] Figure 2 This is a schematic diagram of a single-stage amplifier circuit in the main signal link of an embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of a single-stage amplifier circuit in the signal replication link in an embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram of the phase detection circuit in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram illustrating the changes in bandwidth compensation control signal 1, main signal link output, and signal replication link output in an embodiment of the present invention.

[0030] Figure 6 This is a schematic diagram illustrating the changes in bandwidth compensation control signal 2 and signal replication link signal output in an embodiment of the present invention;

[0031] The attached diagram is labeled as follows: 1. Main signal link, 2. Signal replication link, 3. Phase detector, 4. First amplifier, 5. Amplitude detection circuit, 6. Second amplifier. Detailed Implementation

[0032] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0033] Reference Figure 1 This invention provides an automatic bandwidth compensation circuit based on phase detection, comprising a main signal link 1, a signal replication link 2, a phase detector 3, and a first amplifier 4. Wherein,

[0034] The input terminal of the main signal link 1 receives a data signal and a gain control signal, and the output terminal of the main signal link 1 outputs a data signal and is connected to the input terminal of the phase detector 3.

[0035] The input of signal replication link 2 is connected to the input of signal main link 1, and its output is connected to the input of phase detector 3.

[0036] The output of phase detector 3 is connected to the input of first amplifier 4, and the output of first amplifier 4 is connected to the bandwidth compensation control terminal of main signal link 1.

[0037] In this embodiment, the main signal link 1 includes an N-stage amplifier link, where N≥1; its input terminal transmits signals, and the gain of the entire link is controlled by a gain control signal.

[0038] like Figure 2 As shown, the single-stage amplifier circuit in the main signal link 1 includes transistors Q1 and Q2. The bases of transistors Q1 and Q2 are connected to the signal input terminals Vinp and Vinn, respectively. The collector of transistor Q1 is connected to resistor R1 and serves as the negative output terminal OUTN of the circuit. The collector of transistor Q2 is connected to resistor R2 and serves as the positive output terminal OUTP of the circuit. The emitter of transistor Q1 is connected to current source I0, and the emitter of transistor Q2 is connected to current source I1. The emitters of transistors Q1 and Q2 are connected to each other through an adjustable resistor R3 and an adjustable capacitor C1, respectively. The adjustable resistor R3 is also connected to the gain control signal terminal VGC, and the adjustable capacitor C1 is also connected to the bandwidth compensation control signal terminal VCOMP.

[0039] Signal replication link 2 includes an amplifier link with the same number of stages as signal main link 1, and its input terminal transmits a replicated input data signal as a reference signal.

[0040] like Figure 3 As shown, the single-stage amplifier circuit in signal replication link 2 includes transistors Q3 and Q4. The bases of transistors Q3 and Q4 are connected to the signal input terminals Vinp and Vinn, respectively. The collector of transistor Q3 is connected to resistor R4 and serves as the negative output terminal OUTN of the circuit. The emitter of transistor Q3 is connected to resistor R5, capacitor C2, and capacitor C3, respectively. The collector of transistor Q4 is connected to resistor R6 and serves as the positive output terminal OUTP of the circuit. The emitter of transistor Q4 is connected to resistor R5, the other end of capacitor C2, and capacitor C4, respectively. The other end of capacitor C4 is connected to the other end of capacitor C3 via a single-pole switch.

[0041] The first amplifier 4 is specifically a low-pass filter amplifier.

[0042] The signals of the main signal link 1 and the signals of the signal replication link 2 are phase-detected by the phase detector 3, and the phase detection result is converted into a bandwidth compensation control signal by the first amplifier 4. The bandwidth of the main signal link 1 is adjusted by the bandwidth compensation control signal so that the transmission AC characteristics of the main signal link 1 are consistent with the transmission characteristics of the signal replication link 2.

[0043] like Figure 4As shown, the phase detector 3 uses a phase detection circuit including transistors Q5, Q6, Q7, and Q8. The bases of transistors Q5 and Q6 are connected to the signal 2 input terminals Vinp2 and Vinn2, respectively. The collector of transistor Q5 is connected to the signal output terminal OUTN and is connected through resistor R7. The collector of transistor Q6 is connected to the signal output terminal OUTP and is connected through resistor R8. The emitters of transistors Q5 and Q6 are both connected to the collector of transistor Q7. The bases of transistors Q7 and Q8 are connected to the signal 1 input terminals Vinp1 and Vinn1, respectively. The emitters of transistors Q7 and Q8 are both grounded. The collector of transistor Q8 is connected to...

[0044] When the gain of the main signal link 1 changes, the phase detection feedback loop adjusts the bandwidth of the main signal link 1 so that its transmission characteristics remain consistent with those of the signal replication link 2.

[0045] This invention uses a phase detector 3 to detect the phase deviation of the data signals at the output terminals of the main signal link 1 and the signal replication link 2, and automatically adjusts the bandwidth compensation of the main signal link 1. This ensures the consistency of bandwidth and delay of the circuit under different gain conditions, and avoids large-scale temperature compensation of the circuit, thus avoiding the extremely high design difficulty caused by sudden changes in device characteristics.

[0046] like Figure 5 As shown, when the input signal is small and signal replication link 2 does not require compensation, the output signal characteristics of signal replication link 2 remain stable. Due to the high voltage of bandwidth compensation signal 1, the output signal of the main signal link 1 is overcompensated, resulting in an excessively large peak value and a significant phase difference between it and the output signal of the signal replication link. Phase detector 3 acquires the phase difference between the output signals of the main signal link 1 and signal replication link 2, and converts the phase comparison result into bandwidth compensation signal 1 through low-pass filter amplifier 4, controlling the compensation of the main signal link 1. When the voltage of bandwidth compensation signal 1 decreases, the bandwidth of the main signal link 1 decreases accordingly, the swing of the output signal decreases, and the phase shifts backward. When the phase difference between the output signal of the main signal link 1 and the output signal of signal replication link 2 is 0, bandwidth compensation signal 1 remains stable, and the circuit operating point is established.

[0047] In this embodiment, the compensation circuit of the present invention further includes an amplitude discrimination circuit 5 and a second amplifier 6;

[0048] The input terminal of the amplitude discrimination circuit 5 is connected to the output terminal of the signal replication link 2, the output terminal of the amplitude discrimination circuit 5 is connected to the input terminal of the second amplifier 6, and the output terminal of the second amplifier 6 is connected to the bandwidth compensation control terminal of the signal replication link 2.

[0049] The second amplifier 6 is specifically a low-pass filter amplifier.

[0050] This invention takes into account that since the signal replication link 2 has no gain change, its output signal will be limited, and the transmission characteristics before and after the circuit limitation will have a slight deviation. Therefore, the amplitude of the output signal of the signal replication link 2 is determined by the amplitude discrimination circuit 5. When the output signal amplitude of the signal replication link 2 is limited, the bandwidth characteristics of the signal replication link 2 are adjusted to make the transmission characteristics of the signal replication link 2 more consistent before and after the limitation.

[0051] This link primarily adjusts the circuit transmission characteristics based on signal replication link 2. A feedback loop ensures that the transmission characteristics of signal transmission link 1 are consistent with those of signal transmission link 2, preventing significant changes in circuit performance due to factors such as temperature deviations, voltage deviations, and gain variations. The transmission characteristics are automatically adjusted by the loop, eliminating the need for complex voltage conversion and avoiding the extremely high design complexity caused by abrupt changes in device characteristics during gain adjustment.

[0052] like Figure 6 As shown, when the output signal of signal replication link 2 is clipped and limited, the amplitude discrimination circuit 5 converts the limited signal into bandwidth compensation signal 2 through low-pass filter amplifier 6. The bandwidth compensation signal 2 switches from high voltage to low voltage to compensate for the phase delay of the output signal of signal replication link 2. From the relationship between bandwidth and phase, the phase delay compensation is directly reflected in the reduction of circuit bandwidth and the slower rise time of the signal.

[0053] Specific embodiments have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

[0054] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. An automatic bandwidth compensation circuit based on phase detection, characterized in that, include: Signal main link (1), signal replication link (2), phase detector (3), first amplifier (4), amplitude discrimination circuit (5), and second amplifier (6); The input terminal of the main signal link (1) receives a data signal and a gain control signal, and the output terminal of the main signal link (1) outputs a data signal and connects to the input terminal of the phase detector (3). The input terminal of the signal replication link (2) is connected to the input terminal of the main signal link (1), and its output terminal is connected to the input terminal of the phase detector (3); the input terminal of the amplitude discrimination circuit (5) is connected to the output terminal of the signal replication link (2), and its output terminal is connected to the input terminal of the second amplifier (6); the output terminal of the second amplifier (6) is connected to the bandwidth compensation control terminal of the signal replication link (2). The output of the phase detector (3) is connected to the input of the first amplifier (4), and the output of the first amplifier (4) is connected to the bandwidth compensation control terminal of the main signal link (1). The phase detector (3) detects the phase deviation of the data signals at the output of the main signal link (1) and the signal replication link (2), and converts it into a bandwidth compensation control signal through the first amplifier (4) to adjust the bandwidth of the main signal link (1) so that the transmission AC characteristics of the main signal link (1) are consistent with the transmission characteristics of the signal replication link (2).

2. The automatic bandwidth compensation circuit based on phase detection according to claim 1, characterized in that, The main signal link (1) includes an N-stage amplifier link, where N ≥ 1.

3. The automatic bandwidth compensation circuit based on phase detection according to claim 2, characterized in that, The signal replication link (2) includes an amplifier link with the same number of stages as the main signal link (1).

4. The automatic bandwidth compensation circuit based on phase detection according to claim 1, characterized in that, The first amplifier (4) is a low-pass filter amplifier.

5. The automatic bandwidth compensation circuit based on phase detection according to claim 4, characterized in that, The second amplifier (6) is a low-pass filter amplifier.

Images