CN-121741301-B - IQ demodulation-based impedance calculation measurement and calibration method

Abstract

The invention discloses a measuring and calibrating method for calculating impedance based on IQ demodulation, and belongs to the technical field of measuring and calibrating impedance. The invention measures the voltage and current of voltage and current wave signals in a voltage-current coupler circuit by coupling the voltage and current wave signals to obtain original current and original voltage signals, and the impedance value in the circuit is obtained as known impedance, according to the known impedance, original current and original voltage signals, the error M affecting the final calculated impedance is calculated according to the I value and Q value of direct current signals reflecting the voltage and current waves and the corresponding known impedance, the final standard impedance value is calculated by correcting the error caused by reading the value, the test impedance is the power of transmitting the frequency to the known impedance, and the calibration factor is introduced The following relationship between the actual impedance and the test impedance can be confirmed, and the actual impedance can be determined.

Inventors

• CHENG ZIQIAN
• LI LIANGLIANG
• CHEN JUNWEI

Assignees

• 安徽曦融兆波科技有限公司

Dates

Publication Date

20260512

Application Date

20260228

Claims (6)

1. 1. A method for measuring and calibrating impedance based on IQ demodulation calculation, comprising: Measuring the voltage and current of the voltage wave signal and the current wave signal in the voltage-current coupler circuit by adopting the voltage and current of the coupled voltage wave signal and the current wave signal to obtain an original current signal And the original voltage signal ; Obtaining an impedance value in the circuit by a standard component or a measurement mode, and taking the impedance value as a known impedance; based on known impedance and raw current signal Original voltage signal Correspondingly obtaining two groups of direct current signal I values and direct current signal Q values reflecting the voltage waves and the current waves; According to the direct current signal I value and the direct current signal Q value reflecting the voltage wave and the current wave and the corresponding known impedance, calculating an error M caused by affecting the final calculated impedance, and setting the error M caused by an impedance detection system of the IQ demodulation calculated impedance as a standard calibration factor of a single system; reading the value with the error, and calculating a final standard impedance value by correcting the error caused by the read value; Also includes testing impedance Test impedance The voltage wave and the current wave with amplitude and phase offset are obtained by dividing the known impedance by the incident frequency power and coupled out by a coupling circuit; Introducing a calibration factor Can confirm And (3) with There is the following relationship, determining the actual impedance : Wherein M is a calibration factor, wherein, Representing the amplitude error of the voltage output signal, Representing the phase shift of the voltage output signal, Representing the amplitude error of the current output signal, Representing the phase offset of the current output signal.
2. 2. The method for measuring and calibrating impedance based on IQ demodulation as recited in claim 1, wherein the corresponding DC signal Value and direct current signal Value by original voltage signal Original current signal Mixing with the same-frequency signal, and obtaining by low-pass filtering; specifically, the DC signal With direct current signals The components calculate and represent the original signal: the original signals generating amplitude offset and phase offset through the coupling circuit can be represented by the direct current signals I and Q, and the following relations are satisfied: Wherein: representing the true amplitude of the original signal, Representing the true phase of the original signal, The signal obtained after the high-frequency signal component is filtered by the low-pass filter is represented, the signal representation before the signal I (t) passes through the LPF is related to time t, the signal after the signal I (t) passes through the LPF is filtered by the filtering to remove the high-frequency component, the signal after the signal I (t) passes through the LPF is unrelated to the time t, only a direct current component is left, the two dimensions of the amplitude and the phase of a single specific signal are required, and the two dimensions can be described after the signal is converted into a complex domain; Representing the amplitude change error produced by the voltage passing through the fixed circuitry, Representing the fixed phase offset of the system generated by the sampled voltage signal or current signal through the fixed circuitry, Representing the total gain produced by the overall circuit, Representing complex numbers, j representing imaginary units, The real number representing I is added to the imaginary number of Q.
3. 3. The method for measuring and calibrating impedance based on IQ demodulation according to claim 2, wherein the DC signal Is obtained by: The voltage signal originally coupled in is: ; after passing through the circuit system, the phase and the amplitude are both in error, and after passing through the coupler for coupling the voltage wave signal and the current wave signal, the amplitude and the phase of the original signal are both changed, and the signals after the change can be expressed as: ; local oscillator signal The multiplication can be obtained: Wherein, the Representing the original Abbreviations of (a); the sum and difference formula of the triangle function integration can be used for obtaining: filtering high frequency components by a low pass filter and using Indicating the total gain to obtain DC signal 。
4. 4. The IQ-demodulation-based impedance measurement and calibration method according to claim 3, wherein the DC signal Is obtained by: then for local oscillator signals The multiplication can be obtained: the sum and difference formula of the triangle function integration can be used for obtaining: the high frequency component is filtered out by a low pass filter and used Indicating the total gain to obtain DC signal 。
5. 5. The IQ-demodulation-based impedance measurement and calibration method according to claim 4, wherein the raw voltage signal Original current signal There is a real number domain, which is transformed to a complex number domain by transformation; ; the real part of the signal in the complex domain can be converted back into a real domain signal: Original voltage signal The generated signals of amplitude deviation and phase deviation And the original current signal The generated signals of amplitude deviation and phase deviation It is possible to obtain: For the actual impedance The method comprises the following steps: the impedance obtained by the test is the test impedance : Representing the voltage coupled signal, the direct current component I read out by the ideal filter after IQ demodulation, Representing the voltage-coupled signal, the direct current component Q read out by the ideal filter after IQ demodulation, Representing the DC component I of the current coupled signal, which is read out by the ideal filter after IQ demodulation, Representing the DC component Q of the current-coupled signal, which is read by the ideal filter after IQ demodulation, and the value read by the calibration, and the calibration factor coefficient inherent in the system The final real impedance is calculated.
6. 6. The IQ-demodulation-based impedance measurement and calibration method as claimed in claim 5, further comprising impedance calibration, wherein the calculated values represent values added by complex operations after IQ demodulation after accessing the known calibration impedance And (3) with The following formula is satisfied: , , , The mapped measured voltage wave and current wave represent two sets of IQ values obtained by IQ demodulation after accessing the known calibration impedance, wherein the two sets of IQ values comprise errors, Representing the amplitude error of the voltage output signal, Representing the amplitude error of the current output signal And (3) with The value is the amplitude value corresponding to the actual impedance value, and the ratio is any impedance For the measured error-containing impedance, then any impedance is selected; The system error factor: the calibration factor can be derived from the data: Thus, facing unknown impedance, can be read , , , Calculating , Representing the voltage-coupled signal, the value read out after IQ demodulation, Representing the voltage-coupled signal, the value read out after IQ demodulation, Representing the value read out of the current coupled signal after IQ demodulation, Representing the current-coupled signal, the values read out after IQ demodulation, and the corresponding values can be calculated And (3) with The following formula is satisfied: and simultaneously calculating the ratio: The final impedance satisfies the formula: the error factors introduced by data deduction are calibrated through any impedance, the corresponding error factors are calibrated, and the corresponding real impedance is calculated according to the error factor readings.

Description

IQ demodulation-based impedance calculation measurement and calibration method Technical Field The invention belongs to the technical field of impedance measurement and calibration, and particularly relates to a measurement and calibration method for calculating impedance based on IQ demodulation. Background The impedance calculation often depends on the coupled current and voltage signals, in actual work, the coupled signals often generate amplitude and phase errors, a higher-precision calculation and calibration method is often needed for the errors of the circuit system, and the traditional calibration method often needs to collect various impedance values for high calibration. Disclosure of Invention The invention aims to provide a measuring and calibrating method for calculating impedance based on IQ demodulation. The invention is realized by the following technical scheme: The invention relates to a measuring and calibrating method for calculating impedance based on IQ demodulation, which adopts the voltage and current of coupling voltage wave signal and current wave signal to measure the voltage wave signal and current wave signal in a voltage-current coupler circuit to obtain an original current signal And the original voltage signal; Obtaining an impedance value in the circuit by a standard component or a measurement mode, and taking the impedance value as a known impedance; based on known impedance and raw current signal Original voltage signalCorrespondingly obtaining two groups of direct current signal I values and direct current signal Q values reflecting the voltage waves and the current waves; According to the direct current signal I value and the direct current signal Q value reflecting the voltage wave and the current wave and the corresponding known impedance, calculating an error M caused by affecting the final calculated impedance, and setting the error M caused by an impedance detection system of the IQ demodulation calculated impedance as a standard calibration factor of a single system; reading the value with the error, and calculating a final standard impedance value by correcting the error caused by the read value; Also includes testing impedance Test impedanceThe voltage wave with amplitude and phase offset is coupled to the known impedance through the coupling circuit and the current wave is obtained by dividing the voltage wave with amplitude and phase offset; Introducing a calibration factor Can confirmAnd (3) withThere is the following relationship, determining the actual impedance: Wherein M is a calibration factor, wherein,Representing the amplitude error of the voltage output signal,Representing the phase shift of the voltage output signal,Representing the amplitude error of the current output signal,Representing the phase offset of the current output signal. Wherein, the corresponding direct current signalValue and direct current signalValue by original voltage signalOriginal current signalMixing with the same-frequency signal, and obtaining by low-pass filtering; specifically, the DC signal With direct current signalsThe components calculate and represent the original signal: Specifically, the original signals generating the amplitude offset and the phase offset through the coupling circuit can be represented by the direct current signals I and Q, so as to satisfy the following relations: Wherein: representing the true amplitude of the original signal, Representing the true phase of the original signal,The signal obtained after the high-frequency signal component is filtered by the low-pass filter is represented, the signal representation before the signal I (t) passes through the LPF is related to time t, the signal after the signal I (t) passes through the LPF is unrelated to time t because the high-frequency component is filtered by the filtering, only a direct current component is left after the signal I (t) passes through the LPF, two dimensions of amplitude and phase are required for expressing a single specific signal, and the two dimensions can be described after the signal I (t) is converted into a complex domain; Representing the amplitude change error produced by the voltage passing through the fixed circuitry, Representing the fixed phase offset of the system generated by the sampled voltage signal or current signal through the fixed circuitry,Representing the total gain produced by the overall circuit, i.e., the normalized circuit amplitude gain of the produced circuit,Representing complex numbers, j representing imaginary units,The real number representing I is added to the imaginary number of Q. Specifically, the direct current signalIs obtained by: The voltage signal originally coupled in is: ; after passing through the circuit system, the phase and the amplitude are both in error, and after passing through the coupler for coupling the voltage wave signal and the current wave signal, the amplitude and the phase of the original signal are both changed, and