A quadrature signal phase detection circuit and method

Abstract

The present invention relates to the technical field of orthogonal signal phase detection, and discloses a quadrature signal phase detection circuit and method. By constructing an orthogonal phase detection circuit comprising a frequency mixing difference circuit, a first filtering circuit, and a detector, the two mixers of the frequency mixing difference circuit are used to respectively achieve self-mixing of the I-path signal and the Q-path signal. After the mixing results are differenced, the DC signal is filtered out by the first filtering circuit, and finally a detection signal is obtained by the detector. When the phase difference between the I-path signal and the Q-path signal is the standard 90°, the final detection signal is 0. When the phase difference between the I-path signal and the Q-path signal is not the standard 90°, the amplitude of the final detection signal is proportional to Δφ. The detector can extract a detection voltage proportional to Δφ. Compared with traditional methods, the present invention solves the problems of system resource occupation and the need for re-detection for different signal frequencies by performing automatic phase detection of the orthogonal signal at the analog signal end.

Description

Technical Field

[0001] The present invention relates to the technical field of quadrature signal phase detection, and in particular to a quadrature signal phase detection circuit and method. Background Art

[0002] Ideal quadrature signals (I / Q) refer to two signals with a phase difference of 90°, such as Figure 1 As shown in (a). Orthogonal signals are widely used in electronic systems. For example, in radio frequency conversion systems, orthogonal signals can be used to suppress image frequency signals, thereby suppressing the interference of signals at the image frequency point on useful signals; in communication systems, orthogonal signals can also be used to carry different information, thereby doubling the channel capacity within the same frequency band resources. However, in reality, generating ideal orthogonal signals is a major difficulty in circuit design. On the one hand, the phase error of the orthogonal signal will be affected by the mismatch between devices in the I / Q generation circuit. On the other hand, the device characteristics in the I / Q generation circuit will change with frequency, resulting in the phase difference between the I / Q signals being related to the frequency, so that the actual orthogonal signal often has certain errors, such as Figure 1 (b) As a result, it is difficult to maintain good orthogonality within the signal bandwidth required by the electronic system. Therefore, in the increasingly demanding electronic systems, the detection of orthogonal signal phase error, as the first step in phase calibration, plays an important role and significance in improving the electronic system's anti-interference ability and signal processing rate.

[0003] In traditional orthogonal signal calibration circuits, there is often a lack of direct detection of the orthogonal signal phase at the analog signal processing end. Instead, subsequent digital signal processing circuits are used to convert the signals into digital domain signals for processing, such as Figure 2 This method requires more system resources and requires re-detection for different signal frequencies. Summary of the Invention

[0004] The present invention provides a quadrature signal phase detection circuit and method, aiming to solve at least one of the above technical problems.

[0005] To achieve the above object, the present invention provides a quadrature signal phase detection circuit, comprising:

[0006] The mixing and difference circuit is configured to perform self-mixing on the I-channel signal and the Q-channel signal in the orthogonal signal and then perform difference calculation to obtain a mixing and difference signal;

[0007] a first filtering circuit connected to an output end of the difference circuit, wherein the filtering circuit is configured to filter out a DC signal in the mixed difference signal to obtain a difference filtered signal;

[0008] The detector is connected to the output end of the first filtering circuit, and is configured to extract a detection voltage from the difference filtering signal and determine the phase error of the orthogonal signal according to the detection voltage.

[0009] Optionally, the frequency mixing and difference circuit includes a frequency mixing circuit and a difference circuit;

[0010] The mixing circuit includes a first mixer and a second mixer, and the first mixer and the second mixer are configured to perform self-mixing on the I-channel signal and the Q-channel signal in the quadrature phase signal, respectively, to obtain a first mixed signal and a second mixed signal;

[0011] The difference circuit is connected to the output end of the first mixer and the output end of the second mixer, and is configured to perform a difference calculation on a first mixing signal output by the first mixer and a second mixing signal output by the second mixer to obtain a mixing difference signal.

[0012] Optionally, the first mixing signal and the second mixing signal are expressed as follows:

[0013]

[0014] Where, is the hypothetical expression of the I-channel signal, is the hypothetical expression of the Q-path signal, and Δφ represents the error phase between the I-path signal and the Q-path signal that deviates from the ideal phase.

[0015] Optionally, the first mixer and the second mixer in the mixing circuit are configured to adopt a double-balanced Gilbert mixer structure.

[0016] Optionally, the difference circuit includes a first load branch and a second load branch configured with a first load resistor, the first end of the first load branch and the first end of the second load branch are commonly connected to the mixing difference output end, and the output ends of the first mixer and the second mixer are connected to the second end of the first load branch and the second end of the second load branch in anti-phase with each other.

[0017] Optionally, the first filtering circuit uses a series-connected DC blocking capacitor, the first end of the DC blocking capacitor is connected to the mixing difference output end of the mixing difference circuit, and is configured to receive the mixing difference signal output by the mixing difference circuit, and the second end of the DC blocking capacitor is connected to the input end of the detector.

[0018] Optionally, the expression of the difference filtering signal output by the first filtering circuit is specifically:

[0019] ;

[0020] Where, To obtain the difference filtered signal, Indicates the phase error between the I and Q signals, which is the deviation from the ideal phase.

[0021] Optionally, the detector includes a rectifier circuit, the input end of the rectifier circuit is connected to the output end of the filter circuit, and is configured to receive the difference filter signal of the filter circuit; the output end of the rectifier circuit is connected in parallel with a second load resistor and a second filter circuit, and is configured to convert the amplitude of the difference filter signal into a current output to the second load resistor and filter out the AC signal to extract the detection voltage.

[0022] Optionally, the second filtering circuit uses parallel filtering capacitors and is configured to filter out AC signals in the detection voltage to obtain a stable level signal.

[0023] In addition, in order to achieve the above object, the present invention also provides an orthogonal signal phase detection method, comprising the following steps:

[0024] Performing self-mixing on the I-channel signal and the Q-channel signal in the orthogonal signal and then performing difference calculation to obtain a mixed difference signal;

[0025] Filtering the DC signal in the mixed difference signal to obtain a difference filtered signal;

[0026] A detection voltage is extracted from the difference filter signal, and a phase error of the quadrature signal is determined based on the detection voltage.

[0027] The beneficial effects of the present invention are as follows: a quadrature signal phase detection circuit and method are proposed, which constructs a quadrature phase detection circuit including a mixing difference circuit, a first filtering circuit, and a detector. The two mixers of the mixing difference circuit are used to respectively realize self-mixing of the I-path signal and the Q-path signal. After the mixing results are differentiated, the DC signal is filtered out by the first filtering circuit, and finally a detection signal is obtained by the detector. When the phase difference between the I-path signal and the Q-path signal is the standard 90°, the final detection signal is 0. When the phase difference between the I-path signal and the Q-path signal is not the standard 90°, the amplitude of the final detection signal is proportional to Δφ. The detection voltage proportional to Δφ can be extracted by the detector. Compared with traditional methods, the present invention can solve the problems of system resource occupation and the need for re-detection for different signal frequencies by performing automatic phase detection of the quadrature signal at the analog signal end. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 (a) is a schematic diagram of an ideal orthogonal signal, and (b) is a schematic diagram of the phase error of an actual signal;

[0029] Figure 2 Schematic diagram of a traditional phase detection method;

[0030] Figure 3 is a schematic diagram of a quadrature phase detection circuit of the present invention;

[0031] Figure 4 Schematic diagram of the mixing and difference circuit of the present invention;

[0032] Figure 5 is a schematic diagram of the detector of the present invention;

[0033] Figure 6 Schematic diagram of the simulation results of orthogonal signal phase detection of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0035] An embodiment of the present invention provides a quadrature signal phase detection circuit, comprising:

[0036] The mixing and difference circuit is configured to perform self-mixing on the I-channel signal and the Q-channel signal in the orthogonal signal and then perform difference calculation to obtain a mixing and difference signal;

[0037] a first filtering circuit connected to an output end of the difference circuit, wherein the filtering circuit is configured to filter out a DC signal in the mixed difference signal to obtain a difference filtered signal;

[0038] The detector is connected to the output end of the first filtering circuit, and is configured to extract a detection voltage from the difference filtering signal and determine the phase error of the orthogonal signal according to the detection voltage.

[0039] In a preferred embodiment, the frequency mixing and difference circuit includes a frequency mixing circuit and a difference circuit;

[0040] The mixing circuit includes a first mixer and a second mixer, and the first mixer and the second mixer are configured to perform self-mixing on the I-channel signal and the Q-channel signal in the quadrature phase signal, respectively, to obtain a first mixed signal and a second mixed signal;

[0041] The difference circuit is connected to the output end of the first mixer and the output end of the second mixer, and is configured to perform a difference calculation on a first mixing signal output by the first mixer and a second mixing signal output by the second mixer to obtain a mixing difference signal.

[0042] In this embodiment, the first mixer and the second mixer in the mixing circuit are configured to adopt a double-balanced Gilbert mixer structure.

[0043] On this basis, the difference circuit includes a first load branch and a second load branch configured with a first load resistor, the first end of the first load branch and the first end of the second load branch are commonly connected to the mixer difference output end, and the output ends of the first mixer and the second mixer are connected to the second end of the first load branch and the second end of the second load branch in anti-phase with each other.

[0044] In a preferred embodiment, the first filtering circuit uses a series-connected DC blocking capacitor, a first end of the DC blocking capacitor is connected to the mixing difference output end of the mixing difference circuit, and is configured to receive the mixing difference signal output by the mixing difference circuit, and a second end of the DC blocking capacitor is connected to the input end of the detector.

[0045] In a preferred embodiment, the detector includes a rectifier circuit, the input end of the rectifier circuit is connected to the output end of the filter circuit, and is configured to receive the difference filter signal of the filter circuit; the output end of the rectifier circuit is connected in parallel with a second load resistor and a second filter circuit, and is configured to convert the amplitude of the difference filter signal into a current output to the second load resistor and filter out the AC signal to extract the detection voltage.

[0046] Furthermore, the second filtering circuit uses parallel filtering capacitors and is configured to filter out the AC signal in the detection voltage to obtain a stable level signal.

[0047] It should be noted that in traditional orthogonal signal calibration circuits, there is often a lack of direct detection of the orthogonal signal phase at the analog signal processing end. Instead, a subsequent digital signal processing circuit is used to convert the signal into a digital domain signal for processing, such as Figure 2 This method requires more system resources and requires re-detection for different signal frequencies.

[0048] To solve the above problems, this embodiment proposes a quadrature signal phase detection circuit and method. By constructing a quadrature phase detection circuit including a mixing difference circuit, a first filtering circuit, and a detector, the two mixers of the mixing difference circuit are used to respectively realize self-mixing of the I-path signal and the Q-path signal. After the mixing results are differentiated, the DC signal is filtered out through the first filtering circuit. Finally, the detection signal is obtained by the detector, and the detection voltage with an amplitude proportional to Δφ is obtained, thereby determining the phase error of the quadrature signal. Compared with traditional methods, the present invention can solve the problems of system resource occupation and the need for re-detection for different signal frequencies by performing automatic phase detection of the quadrature signal at the analog signal end.

[0049] Specifically, if Figure 3As shown, the quadrature signal phase detection circuit of the present invention is primarily composed of two mixers, a difference circuit connecting the two mixers, a first filter circuit, and a detector. The two mixers implement self-mixing of the I and Q signals, respectively. After the mixing results are subtracted, the DC signal is filtered out using a DC blocking capacitor, and finally, the final detection signal is obtained through the detector. Its basic operating principle is as follows:

[0050] Assume that the expressions of I-path signal and Q-path signal are:

[0051]

[0052] Where Δφ represents the phase error between the I-channel signal and the Q-channel signal, which is the deviation from the ideal phase. After the self-mixing of the signal by the mixer, the value is:

[0053]

[0054] After the mixed signal is DC-blocked, the signal entering the detector is:

[0055]

[0056] From the above formula, we can see that if the phase difference between the I-channel signal and the Q-channel signal is the standard 90°, that is, Δφ=0, then the output detector signal is 0, otherwise the output detector signal amplitude is proportional to Δφ. The detector can extract the detection voltage V proportional to Δφ. DET .

[0057] like Figure 4 The following diagram shows the circuit schematics for I-channel self-mixing, Q-channel self-mixing, and output differencing. The mixer utilizes a classic double-balanced active structure. Its excellent symmetry effectively eliminates input leakage to the output and facilitates output differencing. The I-channel input signal is connected in the same manner as the Q-channel input signal, but their outputs are connected in antiphase to achieve the differencing of the mixer's output currents. After the mixer currents are differentiated, they flow through a load resistor and are converted into a differential voltage signal.

[0058] like Figure 5 The figure shows a typical detection circuit schematic. The rectifier circuit composed of four diodes converts the output signal amplitude into current and outputs it to the load R. DET Terminal, capacitor C DET Used to filter AC signals to obtain stable level signals.

[0059] Figure 6 This is a simulation result diagram of the present invention. The output voltage of the detection circuit is proportional to the phase difference between the I-path signal and the Q-path signal that deviates from the ideal state.

[0060] In another embodiment, the present invention further provides a method for detecting a phase of a quadrature signal, comprising the following steps:

[0061] S1: Perform self-mixing on the I-channel signal and the Q-channel signal in the orthogonal signal and obtain a mixed difference signal;

[0062] S2: Filter out the DC signal in the mixed difference signal to obtain a difference filter signal;

[0063] S3: extracting the detection voltage from the difference filter signal, and determining the phase error of the orthogonal signal according to the detection voltage.

[0064] Other embodiments or specific implementations of the orthogonal signal phase detection method of the present invention can refer to the above-mentioned circuit embodiments and will not be described in detail here.

[0065] Therefore, the present invention proposes an orthogonal signal phase detection circuit and method. By constructing an orthogonal phase detection circuit including a mixing difference circuit, a first filtering circuit and a detector, the two mixers of the mixing difference circuit are used to respectively realize self-mixing of the I-path signal and the Q-path signal. After the mixing results are differed, the DC signal is filtered out by the first filtering circuit, and finally a detection signal is obtained by the detector. By automatically detecting the phase of the orthogonal signal at the analog signal end, the problems of system resource occupation and the need for re-detection for different signal frequencies can be solved.

[0066] It should be understood that, in the description of this specification, reference to terms such as "one embodiment," "another embodiment," "other embodiments," or "first to Nth embodiments" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples.

[0067] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0068] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A quadrature signal phase detection circuit, characterized in that: include: The mixing and difference circuit includes a mixing circuit and a difference circuit, and is configured to perform self-mixing on the I-channel signal and the Q-channel signal in the orthogonal signal and then perform difference calculation to obtain a mixing and difference signal; The mixing circuit includes a first mixer and a second mixer, and the first mixer and the second mixer are configured to perform self-mixing on the I-channel signal and the Q-channel signal in the quadrature phase signal, respectively, to obtain a first mixed signal and a second mixed signal; The difference circuit is connected to the output end of the first mixer and the output end of the second mixer, and is configured to perform a difference calculation on a first mixing signal output by the first mixer and a second mixing signal output by the second mixer to obtain a mixing difference signal; Wherein, the first mixer and the second mixer in the mixing circuit are configured to adopt a double-balanced Gilbert mixer structure; The difference circuit includes a first load branch and a second load branch each configured with a first load resistor, a first end of the first load branch and a first end of the second load branch being commonly connected to a mixer difference output terminal, and output terminals of the first mixer and the second mixer being connected in anti-phase to the second end of the first load branch and the second end of the second load branch. a first filtering circuit connected to an output end of the difference circuit, wherein the filtering circuit is configured to filter out a DC signal in the mixed difference signal to obtain a difference filtered signal; The detector is connected to the output end of the first filtering circuit, and is configured to extract a detection voltage from the difference filtering signal and determine the phase error of the orthogonal signal according to the detection voltage.

2. The quadrature signal phase detection circuit according to claim 1, wherein: The expressions of the first mixing signal and the second mixing signal are specifically: V I =cosω0t Where V I is the hypothetical expression of the I-channel signal, V Q is the hypothetical expression of the Q-path signal, Indicates the phase error between the I and Q signals, which is the deviation from the ideal phase.

3. The quadrature signal phase detection circuit according to claim 1, wherein: The first filtering circuit uses a DC blocking capacitor connected in series, wherein a first end of the DC blocking capacitor is connected to a mixing difference output terminal of the mixing difference circuit and is configured to receive a mixing difference signal output by the mixing difference circuit, and a second end of the DC blocking capacitor is connected to an input terminal of the detector; The expression of the difference filtering signal output by the first filtering circuit is specifically: Where V DIF To obtain the difference filtered signal, Indicates the phase error between the I and Q signals, which is the deviation from the ideal phase.

4. The quadrature signal phase detection circuit according to claim 1, wherein: The detector includes a rectifier circuit, the input end of the rectifier circuit is connected to the output end of the filter circuit, and is configured to receive the difference filter signal of the filter circuit. The output end of the rectifier circuit is connected in parallel with a second load resistor and a second filter circuit, and is configured to convert the amplitude of the difference filter signal into a current and output it to the second load resistor and filter out the AC signal to extract the detection voltage.

5. The quadrature signal phase detection circuit according to claim 4, wherein: The second filtering circuit uses parallel-connected filtering capacitors and is configured to filter out the AC signal in the detection voltage to obtain a stable level signal.

6. A method for detecting phase of an orthogonal signal, characterized in that: The quadrature signal phase detection circuit according to any one of claims 1 to 5 comprises the following steps: Performing self-mixing on the I-channel signal and the Q-channel signal in the orthogonal signal and then performing difference calculation to obtain a mixed difference signal; Filtering the DC signal in the mixed difference signal to obtain a difference filtered signal; A detection voltage is extracted from the difference filter signal, and a phase error of the quadrature signal is determined based on the detection voltage.

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