Electronic signal orthogonal homodyne phase discrimination system

Abstract

An electronic signal orthogonal homodyne phase discrimination system relates to the field of electronic technology and radio and television, solves the problems that the amplitude heights of two input signals are required to be equal, the measurement precision is not high and the structure of a measurement circuit is complex in the prior art, and comprises two signal input ends, resistors R1-R11, capacitors C1-C4 and diodes D1-D4, operational amplifiers U1 to U3 and an output end; the system adopts an operational amplifier to measure two input signals in a superposition manner; when the device is used for measuring the phase difference of the two signals, the output voltage of the device is in direct proportion to the amplitude of the smaller signal in the two input signals multiplied by the cosine value corresponding to the phase difference of the two signals; when the phase difference of the two cosine input signals is 90 degrees and the two cosine input signals are orthogonal, the output voltage of the device is always zero no matter what the amplitudes of the two input signals change, so that the amplitudes of the two input signals are not required to be equal when the device is used in an orthogonal phase discrimination occasion.

Description

Technical Field

[0001] The present invention relates to the field of electronic technology and broadcasting television, and in particular to an electronic signal orthogonal homodyne phase detection system. The phase detection device of the present invention is applied to a frequency synthesizer as a phase detector to generate two mutually orthogonal signals, which are used to design an orthogonal mixing device. In digital television and broadcasting systems, orthogonal modulation can ensure the quality of stable signal transmission, and orthogonal demodulation can extract and restore video and audio signals. Background Art

[0002] The measurement of electronic signal phase difference has shown its indispensable importance in many fields of science and technology and application. In communication systems, accurate measurement of phase difference is the key to achieving synchronous demodulation of signals, which ensures the accuracy and stability of data transmission. In the field of electronic engineering, phase difference measurement technology is widely used in the testing of frequency synthesizers, signal reconstruction processing, and filter optimization design, providing strong support for the performance improvement of electronic equipment. In addition, radio signal interferometers can accurately determine the direction of the signal source by precisely measuring the phase difference of electronic signals. In the field of radio and television, the reason why orthogonal modulation and demodulation technology is widely used is that the accurate measurement and control of phase difference ensures the transmission quality of program sound and image, bringing a clear and stable audio-visual experience to the audience. In terms of measuring the phase difference of analog signals, most existing phase detectors use a zero-crossing comparator to convert the analog cosine signal into a square wave, and then use the relevant patents ZL201610342982.1 "An automatic digital phase detection circuit and system with a phase difference between signals of 0 to 2π", ZL201810401226.0 "Device and method for measuring the phase difference of electronic signals by random frequency modulation sampling probability", and ZL201810399631.3 "Device and method for measuring the phase difference of electronic signals by mutual prime frequency sampling probability" to perform phase detection on the square wave; because the zero-crossing comparator only uses the information at the zero-crossing point of the cosine signal, When there is an interference signal, the error is large; Patent 201810090361.8 "An electronic signal phase difference measurement device and method" provides a circuit device that can fully utilize all the information of the entire cosine signal. It uses an automatic gain controller to make the two input signals have the same amplitude, and then the signals are superimposed to measure the phase difference. Because there are two automatic gain controllers, the complexity of the circuit is increased, and the automatic gain controller itself has errors; the present invention is improved on this basis, and an operational amplifier is used to directly process the two input signals. When used in orthogonal phase detection applications, the amplitudes of the two input signals are not required to be equal. Summary of the invention

[0003] The invention provides an electronic signal orthogonal homodyne phase detection system to solve the problems that the amplitudes of two input signals are required to be highly equal in the existing electronic signal phase difference measurement, the measurement accuracy is low and the measurement circuit structure is complex.

[0004] An electronic signal orthogonal homodyne phase detection system, the system comprises a signal input terminal INA, a signal input terminal INB, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R9, a capacitor C2, a capacitor C3, diodes D1 to D4, an operational amplifier U1, an operational amplifier U2 and a subtractor unit;

[0005] The first signal is connected through the signal input terminal INA and enters the negative input terminal of the operational amplifier U1 through the resistor R1; the second signal is connected through the signal input terminal INB and enters the negative input terminal of the operational amplifier U1 through the resistor R2; the two signals are summed by the operational amplifier U1 to obtain a summed composite signal;

[0006] At the same time, the first signal is also processed by the voltage division of the resistors R4 and R5 and is directed to the positive input terminal of the operational amplifier U2; the second signal enters the negative input terminal of the operational amplifier U2 through the resistor R3, and the operational amplifier U2 performs the difference calculation on the two signals to obtain a synthetic signal after the difference calculation;

[0007] The summed composite signal is rectified by a diode D3 and filtered by a capacitor C2 to obtain an amplitude X of the summed signal; the differenced composite signal is rectified by a diode D4 and filtered by a capacitor C3 to obtain an amplitude Y of the differenced signal;

[0008] The amplitude X of the sum signal and the amplitude Y of the difference signal are sent to the subtractor unit for subtraction operation, and the obtained voltage signal is output through the output terminal OUTP;

[0009] An external circuit is used to measure the voltage of the output terminal OUTP, to obtain a phase difference Φ between the first signal and the second signal, and the voltage value of the output terminal OUTP is obtained according to the phase difference Φ.

[0010] Beneficial effects of the present invention:

[0011] The circuit design of the present invention makes full use of the comprehensive information of the cosine signal in the entire cycle, so that random noise interference can be significantly suppressed; when measuring the phase difference between two input signals, the unique advantage of the circuit is that the measurement result of its output voltage depends only on the one with the smaller amplitude of the two input voltage signals, and is independent of the signal with the larger amplitude. This feature significantly improves the phase detection accuracy of the present invention compared with the existing traditional phase detection devices; further, in the application scenario of orthogonal phase detection, the present invention has no strict restrictions on the amplitudes of the two input signals. Compared with the traditional analog phase detection that usually requires the performance of the two signal channels to be highly balanced, the circuit of the present invention greatly relaxes the use conditions and can be more flexible and convenient in practical applications.

[0012] The phase detection system of the present invention does not use a multiplier, but uses an operational amplifier to superimpose and measure two input signals; when used to measure the phase difference between the two signals, the output voltage of the device is proportional to the amplitude of the smaller signal of the two input signals multiplied by the cosine value corresponding to the phase difference between the two signals; in particular, when the two cosine input signals are 90 degrees out of phase and orthogonal to each other, no matter how the amplitudes of the two input signals change, the output voltage of the device is always zero, so when used in orthogonal phase detection occasions, it is not required that the amplitudes of the two input signals are equal.

[0013] In the phase-detection system described in the present invention, when the voltage value of the output terminal OUTP returns to zero, it indicates that the two input signals present an orthogonal relationship; especially when the device is applied to the orthogonal phase-detection scenario, the output is zero, which indicates that the orthogonal characteristics of the signals are independent of the amplitudes of the two signals, showing a signal orthogonality judgment mechanism independent of the amplitude; therefore, this property makes the phase-detection device of this embodiment extremely convenient when designing the frequency synthesizer in the orthogonal mixer.

[0014] The phase detection system described in the present invention can use the phase detection device as a phase detector in a frequency synthesizer, and use the error voltage obtained after phase detection to regulate the voltage-controlled oscillator, thereby accurately generating a second local oscillation signal that is orthogonal to the local oscillation reference signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a structural diagram of an electronic signal orthogonal homodyne phase detection device. DETAILED DESCRIPTION

[0016] Combination Figure 1The present embodiment is described, an electronic signal orthogonal zero-difference phase detection system, the system includes a signal input terminal INA, a signal input terminal INB, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a resistor R11, a capacitor C1, a capacitor C2, a capacitor C3, a capacitor C4, a diode D1, a diode D2, a diode D3, a diode D4, an operational amplifier U1, an operational amplifier U2, an operational amplifier U3, an output terminal OUTP, a positive power supply VCC, and a negative power supply VEE; the resistor R7, the resistor R8, the resistor R10, the resistor R11, the operational amplifier U3, the capacitor C1 and the capacitor C4 constitute a subtractor unit;

[0017] The signal input terminal INA is connected to the resistor R1 and the resistor R4; the signal input terminal INB is connected to the resistor R2 and the resistor R3;

[0018] The negative input terminal of the operational amplifier U1 is electrically connected to the resistor R1, the resistor R2, the resistor R6 and the positive terminal of the diode D1; the output terminal of the operational amplifier U1 is connected to the negative terminal of the diode D1 and the positive terminal of the diode D3;

[0019] The negative input terminal of the operational amplifier U2 is connected to the resistor R3, the resistor R9, and the positive terminal of the diode D2; the positive input terminal of the operational amplifier U2 is connected to the resistor R4 and the resistor R5;

[0020] The output end of the operational amplifier U2 is connected to the negative end of the diode D2 and the positive end of the diode D4; the negative end of the diode D3 is connected to the resistor R6, the resistor R7 and the capacitor C2;

[0021] The negative end of the diode D4 is connected to the resistor R9, the resistor R10 and the capacitor C3;

[0022] The negative terminal of the operational amplifier U3 is connected to the resistor R7, the resistor R8 and the capacitor C1;

[0023] The positive terminal of the operational amplifier U3 is connected to the resistor R10, the resistor R11 and the capacitor C4;

[0024] The output end of the operational amplifier U3 is connected to the resistor R8, the capacitor C1 and the output end OUTP;

[0025] The positive power supply terminal of the operational amplifier U1 is electrically connected to the positive power supply terminal of the operational amplifier U2, and the positive power supply terminal of the operational amplifier U3 is electrically connected to the positive power supply VCC;

[0026] The negative power supply terminal of the operational amplifier U1 is electrically connected to the negative power supply terminal of the operational amplifier U2, and the negative power supply terminal of the operational amplifier U3 is electrically connected to the positive power supply VCC;

[0027] The positive input terminal of the operational amplifier U1 is grounded along with the capacitor C2, the resistor R5, the capacitor C3, the capacitor C4 and the resistor R11.

[0028] In this embodiment, two input signals are introduced into the phase detection device via the signal input terminal INA and the signal input terminal INB respectively to perform phase detection measurement;

[0029] The first signal with amplitude A1 is connected from the signal input terminal INA and passes through the resistor R1; the second signal with amplitude A2 is connected from the signal input terminal INB and passes through the resistor R2; the two signals converge at the negative input terminal of the operational amplifier U1, realizing the addition and summation of the two input signals to obtain the summed composite signal. At the same time, the first signal is also processed by the voltage division of resistors R4 and R5 and is directed to the positive input terminal of the operational amplifier U2; the second signal passes through the resistor R3 and reaches the negative input terminal of the operational amplifier U2, thus completing the subtraction and difference operation of the two input signals and obtaining the composite signal after difference.

[0030] In the circuit design of the phase detector described in this embodiment, the resistance values ​​of the resistors R1 and R2 are required to be equal, the resistance value of the resistor R3 is required to be equal to the resistance value of the resistor R5, and the resistance value of R4 is required to be equal to the resistance value of R9. In addition, the ratio of the resistor R6 to the resistor R1 is required to be equal to the ratio of the resistor R9 to the resistor R3. In order to simplify the circuit design and reduce the number of components, the preferred design is to make the resistors R1, R2, R3 and R4 use the same resistance value, and make the resistors R5, R6 and R7 equal in value.

[0031] The synthesized signal after summing by the operational amplifier U1 is rectified by the diode D3 and filtered by the capacitor C2, and the amplitude X of the summed signal is obtained on the capacitor C2. The synthesized signal after difference is rectified by the diode D4 and filtered by the capacitor C3, and the amplitude Y of the difference signal is obtained on the capacitor C3. Subsequently, the amplitude X of the summed signal is sent to the negative input terminal of the operational amplifier U3 through the resistor R7, and the amplitude Y of the difference signal is sent to the positive input terminal of the operational amplifier U3 through the resistor R10.

[0032] The operational amplifier U3 and the resistors R7, R8, R10, and R11 together form a subtraction circuit to implement the subtraction operation of the sum signal amplitude X and the difference signal amplitude Y, and send the result to the output terminal OUTP; the external circuit measures the voltage of the output terminal OUTP, and then calculates the phase difference Φ between the first signal and the second signal by the following formula, and the specific method is as follows;

[0033] If A1 is less than or equal to A2, the phase difference between the two signals is obtained using formula (1);

[0034]

[0035] Otherwise, use formula (2) to obtain the phase difference between the two signals;

[0036]

[0037] In this embodiment, capacitor C1 is connected between the negative input terminal and the output terminal of the operational amplifier U3, and capacitor C4 is connected between the positive input terminal and the ground of the operational amplifier U3. Such a circuit design not only allows the operational amplifier U3 to act as a core component of a subtractor, but also realizes the function of an integration circuit through the synergistic effect with the connected resistor and capacitor. Thanks to this structure, the entire circuit system exhibits a significant suppression effect on random noise and accidental interference signals.

[0038] For the resistors connected to the operational amplifier U3, it is required that the resistance value of the resistor R7 is equal to the resistance value of the resistor R10, and the resistance value of the resistor R8 is also equal to the resistance value of the resistor R11.

[0039] In the circuit design process of the device described in this embodiment, by adjusting the resistance values ​​of the resistors R1, R6, R7 and R8, the sensitivity of the phase detector for measuring weak input signals can be finely set. The core of this design is reflected in the voltage value of the output terminal OUTP, which is accurately expressed as a functional relationship between the two input signals; as shown in Publication (3);

[0040]

[0041] In formula (3), MIN(A1, A2) represents the smaller value between the first signal amplitude A1 and the second signal amplitude A2, and Φ represents the phase difference between the first signal and the second signal. Once the circuit is assembled and the parameters of the components have been determined, the voltage value at the output terminal OUTP depends only on the phase difference Φ and the smaller amplitude of the two signals, and has nothing to do with the specific amplitude value of the larger amplitude signal.

[0042] It can be seen from formula (3) that when the voltage value of the output terminal OUTP of the circuit returns to zero, it indicates that an orthogonal relationship is present between the two input signals; especially when the device is applied to the orthogonal phase-detection scenario, the output is zero, which indicates that the characteristic of signal orthogonality is independent of the amplitude of the two signals, showing a signal orthogonality judgment mechanism independent of amplitude; therefore, this property makes the phase-detection device of this embodiment extremely convenient when designing the frequency synthesizer in the orthogonal mixer; specifically, the phase-detection device can be used as a phase detector in the frequency synthesizer, and the error voltage obtained after the phase-detection is used to regulate the voltage-controlled oscillator, so as to accurately generate a second local oscillation signal orthogonal to the local oscillation reference signal.

[0043] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An electronic signal orthogonal homodyne phase detection system, the system comprising a signal input terminal INA, a signal input terminal INB, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a resistor R9, a capacitor C2, a capacitor C3, diodes D1 to D4, an operational amplifier U1, an operational amplifier U2 and a subtractor unit; wherein: The first signal is connected through the signal input terminal INA and enters the negative input terminal of the operational amplifier U1 through the resistor R1; the second signal is connected through the signal input terminal INB and enters the negative input terminal of the operational amplifier U1 through the resistor R2; the two signals are summed by the operational amplifier U1 to obtain a summed composite signal; At the same time, the first signal is also processed by the voltage division of the resistors R4 and R5 and is directed to the positive input terminal of the operational amplifier U2; the second signal enters the negative input terminal of the operational amplifier U2 through the resistor R3, and the operational amplifier U2 performs the difference calculation on the two signals to obtain a synthetic signal after the difference calculation; The summed composite signal is rectified by a diode D3 and filtered by a capacitor C2 to obtain an amplitude X of the summed signal; the differenced composite signal is rectified by a diode D4 and filtered by a capacitor C3 to obtain an amplitude Y of the differenced signal; The amplitude X of the sum signal and the amplitude Y of the difference signal are sent to the subtractor unit for subtraction operation, and the obtained voltage signal is output through the output terminal OUTP; An external circuit is used to measure the voltage of the output terminal OUTP, to obtain a phase difference Φ between the first signal and the second signal, and the voltage value of the output terminal OUTP is obtained according to the phase difference Φ.

2. The electronic signal orthogonal homodyne phase detection system according to claim 1, characterized in that: An external circuit is used to measure the voltage at the output terminal OUTP to obtain the phase difference Φ between the first signal and the second signal, which is expressed by the following formula: If the amplitude A1 of the first signal is less than or equal to the amplitude A2 of the second signal, the phase difference between the two signals is obtained using formula (1); Otherwise, use formula (2) to obtain the phase difference between the two signals; Then the voltage value of the output terminal OUTP is expressed by formula (3): Wherein, MIN(A1, A2) represents the smaller value of the first signal amplitude A1 and the second signal amplitude A2, r1, r6, r7, r8 are the resistance values ​​of the resistor R1 and the resistor R6 respectively, and r7 and r8 are the resistance values ​​of the resistor R7 and the resistor R8 in the subtractor unit respectively.

3. The electronic signal orthogonal homodyne phase detection system according to claim 1, characterized in that: The signal input terminal INA is connected to one end of the resistor R1 and one end of the resistor R4; The signal input terminal INB is connected to one end of the resistor R2 and one end of the resistor R3; The other end of the resistor R1 is respectively connected to one end of the resistor R6, the negative input end of the operational amplifier U1, the positive end of the diode D1 and the other end of the resistor R2; The other end of the resistor R3 is respectively connected to one end of the resistor R9, the positive end of the diode D2 and the negative input end of the operational amplifier U2; The other end of the resistor R4 is connected to the positive input end of the operational amplifier U2 and one end of the resistor R5 respectively; The output terminal of the operational amplifier U1 is connected to the negative terminal of the diode D1 and the positive terminal of the diode D3; The other end of the resistor R6 is respectively connected to the negative end of the diode D3, one end of the capacitor C2 and the subtractor unit; The positive input terminal of the operational amplifier U2 is connected to one end of the resistor R4 and one end of the resistor R5; The output end of the operational amplifier U2 is connected to the negative end of the diode D2 and the positive end of the diode D4 respectively; The negative end of the diode D4 is connected to the other end of the resistor R9, one end of the capacitor C3 and the subtractor unit respectively.

4. The electronic signal orthogonal homodyne phase detection system according to claim 3, characterized in that: The subtractor unit includes a resistor R7, a resistor R8, a resistor R10, a resistor R11, an operational amplifier U3, a capacitor C1 and a capacitor C4; One end of the resistor R7 is respectively connected to the capacitor C2, the negative end of the diode D3 and the other end of the resistor R6; the other end of the resistor R7 is respectively connected to one end of the capacitor C1, one end of the resistor R8 and the negative input end of the operational amplifier U3; One end of the resistor R10 is respectively connected to the capacitor C3, the negative end of the diode D4 and the other end of the resistor R9; the other end of the resistor R10 is respectively connected to the positive input end of the operational amplifier U3, one end of the capacitor C4 and one end of the resistor R11; The output end of the operational amplifier U3 is respectively connected to the other end of the resistor R8, the other end of the capacitor C1 and the output end OUTP; The positive input terminal of the operational amplifier U1 and the other end of the capacitor C2, the other end of the resistor R5, the other end of the capacitor C3, the other end of the capacitor C4 and the other end of the resistor R11 are all grounded; The positive power supply terminal of the operational amplifier U1 is connected to the positive power supply terminal of the operational amplifier U2, and the positive power supply terminal of the operational amplifier U3 is connected to the positive power supply VCC; The negative power supply terminal of the operational amplifier U1 is connected to the negative power supply terminal of the operational amplifier U2, and the negative power supply terminal of the operational amplifier U3 is connected to the negative power supply VEE.

5. The electronic signal orthogonal homodyne phase detection system according to claim 1, characterized in that: The resistance values ​​of the resistor R1 are equal to the resistance value of the resistor R2 , the resistance value of the resistor R3 is equal to the resistance value of the resistor R5 , and the resistance value of the resistor R4 is equal to the resistance value of the resistor R9 .

6. The electronic signal orthogonal homodyne phase detector according to claim 1, characterized in that: The ratio of the resistor R6 to the resistor R1 is equal to the ratio of the resistor R9 to the resistor R3.

7. The electronic signal orthogonal homodyne phase detector according to claim 1, characterized in that: The resistor R5 has the same value as the resistor R6 and the resistor R7.

8. The electronic signal orthogonal homodyne phase detector according to claim 1, characterized in that: The resistance value of the resistor R7 is equal to the resistance value of the resistor R10 , and the resistance value of the resistor R8 is equal to the resistance value of the resistor R11 .

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