TWI657670B - I/Q imbalance calibration device - Google Patents

Abstract

An I/Q imbalance calibration apparatus includes: a calibration signal generator for selectively generating a first in-phase calibration signal, a first quadrature calibration signal or the first in-phase calibration signal and the first Both of the orthogonal calibration signals; an I/Q imbalance calibrator electrically coupled to the calibration signal generator for receiving the first in-phase calibration signal and the after receiving an I/Q gain imbalance value The first orthogonal calibration signal performs an I/Q gain imbalance compensation; a signal strength acquisition circuit electrically connects the front end circuit of the transmitter system for selectively acquiring and outputting a first to fourth calibration signal strength One of the I/Q imbalance estimators electrically coupled to the signal strength acquisition circuit for selectively estimating one of the first to fourth calibration signal strengths using a difference estimate. Thereby, by estimating and compensating the gain imbalance and phase imbalance of the I and Q channels, it is not necessary to use an analog to digital converter to achieve the purpose of reducing cost and power consumption.

Description

I/Q imbalance calibration device

This invention relates to an unbalanced calibration apparatus, and more particularly to an I/Q imbalance calibration apparatus for use in a transmitter system operating in an I/Q imbalance calibration mode.

In the transmitter system, the baseband signal is subjected to analog conversion, low-pass filtering, local oscillation (LO) signal mixing, in-phase and quadrature signal combination, band-pass filtering, and intermediate frequency (IF) signal mixing. Generating a radio frequency (RF) signal, the above processing can be implemented by multiple circuits, however, the in-phase and quadrature fundamental signals processed by the circuits of the in-phase and quadrature channels (I and Q channels), respectively, vary due to the semiconductor process. There may be an offset. The aforementioned offset, also known as I/Q imbalance, has to be calibrated or corrected to handle I/Q imbalances (including I/Q gain and phase imbalance).

In the prior art, an analog digital converter (ADC) can be used to sample the processed RF signal to calibrate the I/Q imbalance, but the sampling rate of the ADC should be greater than the signal bandwidth of the RF signal, however, for the millimeter wave communication band. For transmitter systems, the signal bandwidth is very large, such as a few gigahertz (GHz), so the ADC should have a sampling rate (Gb/s) of several gigabits per second, and an analog digital converter with an ultra-high sampling rate. Is a challenge, even if it is super high The analog-to-digital converter with sampling rate can also be designed very well, and the huge power consumption caused by the ultra-high sampling rate will also affect the heat dissipation of the transmitter system.

Therefore, there is a great need in the industry to develop a transmitter system that can be used in an I/Q unbalanced calibration mode to perform the estimation of the same direction and orthogonal unbalance without the need of a high speed analog to digital converter. Correction), in order to reduce power consumption and transmitter heat output at the same time, in order to reduce transmitter cost and power consumption.

In view of the above disadvantages of the prior art, the main object of the present invention is to provide an I/Q imbalance calibration apparatus, which integrates a calibration signal generator, an I/Q imbalance calibrator, a signal strength acquisition circuit and an I/Q. Unbalance estimators, etc., to produce transmitters with low power consumption and low heat output.

In order to achieve the above object, according to one aspect of the present invention, an I/Q imbalance calibration apparatus is provided for use in a transmitter system operating in an I/Q imbalance calibration mode, including: a calibration signal generation For selectively generating a first in-phase calibration signal, a first quadrature calibration signal, or both of the first in-phase calibration signal and the first quadrature calibration signal; an I/Q imbalance calibration And electrically connecting the calibration signal generator, for performing an I/Q gain imbalance compensation on the first in-phase calibration signal and the first quadrature calibration signal after receiving an I/Q gain imbalance value a second in-phase calibration signal and a second quadrature calibration signal, and selectively the first in-phase calibration signal, the first quadrature calibration signal, the second in-phase calibration signal, or the second Both the in-phase calibration signal and the second orthogonal calibration signal are output to a front end circuit of the transmitter system; a signal strength acquisition circuit electrically connecting the front end circuit of the transmitter system for selectively acquiring and outputting One of the first to fourth calibration signal strengths, wherein the first to fourth calibration signal strengths correspond to a first to fourth calibration signals, the first to fourth calibration signals being separately processed by the front end circuit a plurality of processing signals generated by the first in-phase calibration signal, the first quadrature calibration signal, the second in-phase calibration signal, and the second in-phase calibration signal and the second orthogonal calibration signal; a /Q imbalance estimator electrically coupled to the signal strength acquisition circuit for selectively estimating one of the first to fourth calibration signal strengths using a difference estimate, estimating an intensity sum based on a first calibration signal A second calibration signal estimate strength calculates the I/Q gain imbalance value, and an I/Q phase imbalance value is calculated based on a third calibration signal estimate strength and a fourth calibration signal estimate strength.

In the above, after performing the calculation of the I/Q gain imbalance value, the calculation of the I/Q phase imbalance value is performed; after the calculation of the I/Q gain imbalance value is performed, the I/Q gain imbalance value is transmitted to The I/Q imbalance calibrator sets the I/Q gain imbalance compensation value; and after performing the calculation of the I/Q phase imbalance value, the I/Q phase imbalance value is transmitted to the I/Q imbalance calibrator to Set the I/Q phase imbalance compensation value.

The signal strength acquisition circuit of the present invention comprises: a square calculation circuit electrically connected to the front end circuit for performing square calculation on one of the received first to fourth calibration signals; and a low pass filter, connection The square calculation circuit and the I/Q imbalance estimator are configured to low pass filter one of the squares of the first to fourth calibration signals to generate one of the first to fourth calibration signal strengths .

In the above system, the I/Q imbalance estimator includes: a difference estimator electrically connected to the signal strength acquisition circuit for generating a reference signal strength according to an accumulated data signal, the reference signal strength and the first to Comparing one of the fourth calibration signal strengths, the accumulated data signal is gradually incremented until the reference signal strength is close to and not less than a corresponding one of the first to fourth calibration signal strengths; and a controller is electrically connected The difference estimator, the I/Q imbalance calibrator, and the calibration signal generator are configured to calculate the I/Q gain imbalance value according to the first and second calibration signal estimated intensities, and according to the third And the fourth calibration signal estimated strength calculates the I/Q phase imbalance value.

The difference estimator of the present invention comprises: a digital analog converter electrically connected to the controller for receiving the accumulated data signal generated by the controller according to an accumulated signal, the digital analog converter being derived from the controller The first clock signal is triggered to perform digital analog conversion on the accumulated data signal to generate the reference signal strength; a comparator electrically connecting the signal strength obtaining circuit and the digital analog converter for using the reference The signal strength is compared with one of the first to fourth calibration signal strengths, and when the reference signal strength is less than a corresponding one of the first to fourth calibration signal strengths, a difference signal is output, and when The reference signal strength is not less than the first to the first When one of the four calibration signal strengths corresponds to one, a zero is output; a delay unit, and an adder electrically connecting the delay unit and the comparator, wherein the delay unit is triggered by a second clock signal from the controller To delay the accumulated signal output from the adder, the adder adds an output signal of the delay unit and an output signal of the comparator to generate the accumulated signal.

The above summary and the following detailed description and drawings are intended to further illustrate the manner, means and effects of the present invention in achieving its intended purpose. Other purposes and advantages of this creation will be explained in the following description and drawings.

1‧‧‧Transmitter

111‧‧‧Calibration signal generator

12‧‧‧I/Q imbalance calibrator

13‧‧‧ front-end circuit

14‧‧‧Signal strength acquisition circuit

15‧‧‧I/Q imbalance estimator

151‧‧‧Delta estimator

S301-S316‧‧‧Steps

I-DAC‧‧‧Non-phase channel digital to analog converter

Q-DAC‧‧‧Orthogonal Channel Digital to Analog Converter

I-LPF‧‧‧Non-phase channel low-pass filter

Q-LPF‧‧‧Orthogonal channel number low pass filter

I-MIX‧‧‧In-phase mixer

Q-MIX‧‧‧Orthogonal Mixer

IQ-PLL‧‧‧phase and quadrature phase-locked loop

COMB‧‧‧Combiner

IF-BPF‧‧‧ medium-frequency pass filter

SQ‧‧‧ squarer

SQ-LPF‧‧‧ low-pass filter accepting squarer output

IF-PLL‧‧‧ medium frequency phase-locked loop

IF-MIX‧‧‧Intermediate frequency mixer

COMP‧‧‧ comparator

ACC-ADD‧‧‧Addition Adder

ACC-REG‧‧‧Accumulate register

CTRL‧‧‧ controller

DAC-1‧‧‧ accepts controller output digital to analog converter

The first figure is a schematic diagram of a transmitter of an I/Q imbalance calibration device of the present invention; the second figure is a flow chart of an I/Q imbalance estimation procedure of the present invention.

The embodiments of the present invention are described by way of specific examples, and those skilled in the art can readily understand the advantages and effects of the present invention from the disclosure of the present disclosure.

The present invention provides an I/Q imbalance calibration apparatus for estimating and compensating for gain imbalance and phase imbalance of I and Q channels in a transmitter system operating in an I/Q imbalance calibration mode (ie, I/Q gain and phase Unbalanced) without the use of ultra-high sample rate ADCs, which can reduce cost and power consumption. In addition, the aforementioned I/Q imbalance calibration apparatus can be applied to a transmitter system of a millimeter wave communication band, such as a fifth generation mobile communication system.

Please refer to the first figure, which is a schematic diagram of a transmitter including an I/Q imbalance calibration device according to the present invention. As shown, the present invention provides an I/Q imbalance calibration apparatus for use in a transmitter system 1 operating in an I/Q imbalance calibration mode, and includes a calibration signal generator 111, an I/Q imbalance calibration. 12, the signal strength acquisition circuit 14 and the I/Q imbalance estimator 15, wherein the calibration signal generator 111 is electrically connected to the I/Q imbalance calibrator 12, and the I/Q imbalance calibrator 12 is electrically connected to the transmitter system The front end circuit 13 of the first, the signal strength acquisition circuit 14 is electrically connected to the front end circuit 13 and the I/Q imbalance estimator 15, and the I/Q imbalance estimator 15 is electrically connected to the calibration signal generator 111 and the I/Q imbalance calibration. 12

Implementation process

Please refer to the second figure, which is a flow chart of an I/Q imbalance estimation procedure according to the present invention. As shown in the figure, in the first embodiment, in step S301, the calibration signal generator 111 generates a first in-phase calibration signal (I(n)=A*cos(w*n), Q(n)=0) to I. /Q imbalance calibrator 12; then, the I/Q imbalance calibrator 12 relays the first in-phase calibration signal to the front end circuit 13; then, the front end circuit 13 processes the first in-phase calibration signal to generate a first calibration signal; Thereafter, the signal strength acquisition circuit 14 acquires the first calibration signal strength and transmits the first calibration signal strength to the I/Q imbalance estimator 15.

Next, in step S302, the I/Q imbalance estimator 15 uses the difference estimate to compare the first calibration signal strength. Further, the I/Q imbalance estimator 15 gradually increases the accumulated data signal DAC-DATA(n) until The accumulated signal ACC(n) is close to not less than the estimated strength of the first calibration signal.

In step S303, I / Q imbalance estimator 15 obtains the estimated intensity corresponding to the first calibration signal accumulated data signal DAC-DATA (n), M 0 = DAC-DATA (n).

In step S304, the calibration signal generator 111 generates a first orthogonal calibration signal (Q(n)=A*cos(w*n), I(n)=0) to the I/Q imbalance calibrator 12; The I/Q imbalance calibrator 12 relays the first orthogonal calibration signal to the front end circuit 13; then, the front end circuit 13 processes the first orthogonal calibration signal to generate a second calibration signal; thereafter, the signal strength acquisition circuit 14 acquires The signal strength is calibrated and the second calibration signal strength is transmitted to the I/Q imbalance estimator 15.

In step S305, the I/Q imbalance estimator 15 uses the difference estimate to compare the second calibration signal strength. Further, the I/Q imbalance estimator 15 gradually increases the accumulated data signal DAC-DATA(n) until accumulated. The signal ACC(n) is close to not less than the estimated strength of the second calibration signal. In step S306, I / Q imbalance estimator 15 obtains the estimated intensity corresponding to the second calibration signal accumulated data signal DAC-DATA (n), M 1 = DAC-DATA (n).

Then, in step S307, the I/Q imbalance estimator 15 calculates an I/Q gain imbalance value ΔG, ΔG = SQRT(M ₁ /M ₀ )-1 based on the first and second calibration signal estimated intensities. SQRT is a square root function; thereafter, in step S308, the I/Q gain imbalance value ΔG is transmitted to the I/Q imbalance calibrator 12 so that the I/Q imbalance calibrator 12 can be received afterwards The signal is corrected for I/Q gain imbalance.

In step S309, the calibration signal generator 111 generates a first in-phase calibration signal (I(n)=A*cos(w*n), Q(n)=0) to the I/Q imbalance calibrator 12; The I/Q imbalance calibrator 12 performs I/Q gain imbalance correction on the first in-phase calibration signal to generate a second in-phase calibration signal to the front end circuit 13; then, the front end circuit 13 processes the second in-phase calibration signal to A third calibration signal is generated; thereafter, the signal strength acquisition circuit 14 acquires the third calibration signal strength and transmits the third calibration signal strength to the I/Q imbalance estimator 15.

In step S310, the I/Q imbalance estimator 15 uses the difference estimate to compare the third calibration signal strength. Further, the I/Q imbalance estimator 15 gradually increases the accumulated data signal DAC-DATA(n) until accumulation. The signal ACC(n) is close to not less than the estimated strength of the third calibration signal.

In step S311, I / Q imbalance estimator 15 to obtain the corresponding estimated intensity of the calibration signal of the third data signal accumulated DAC-DATA (n), K 0 = DAC-DATA (n).

In step S312, the calibration signal generator 111 generates a first in-phase and quadrature calibration signal (I(n)=A*cos(w*n), Q(n)=A*cos(w*n)). I/Q imbalance calibrator 12; then, I/Q imbalance calibrator 12 performs I/Q gain imbalance correction on the first in-phase and quadrature calibration signals to generate second in-phase and quadrature calibration signals Front end circuit 13; then, front end circuit 13 processes second in-phase and positive The calibration signal is passed to generate a fourth calibration signal; thereafter, the signal strength acquisition circuit 14 acquires the fourth calibration signal strength and transmits the fourth calibration signal strength to the I/Q imbalance estimator 15.

In step S313, the I/Q imbalance estimator 15 uses the difference estimate to compare the fourth calibration signal strength. Further, the I/Q imbalance estimator 15 gradually increases the accumulated data signal DAC-DATA(n) until accumulation. The signal ACC(n) is close to not less than the estimated strength of the fourth calibration signal.

In step S314, I / Q imbalance estimator 15 to obtain the corresponding estimated intensity fourth calibration signal accumulated data signal DAC-DATA (n), K 1 = DAC-DATA (n).

In step S315, the I/Q imbalance estimator 15 calculates an I/Q phase imbalance value Δθ, Δθ = sin ^-1 {[1-(K ₁ /2K) based on the first and second calibration signal estimated intensities. ₀ )]}.

In step S316, the I/Q phase imbalance value Δθ is transmitted to the I/Q imbalance calibrator 12 to allow the I/Q imbalance calibrator 12 to perform an I/Q phase imbalance on the received signal. Correction.

The above-described embodiments are merely illustrative of the features and functions of the present invention and are not intended to limit the scope of the technical content of the present invention. Any person skilled in the art can modify and change the above embodiments without departing from the spirit and scope of the creation. Therefore, the scope of protection of this creation should be as listed in the scope of the patent application described later.

Claims (6)

An I/Q imbalance calibration apparatus for use in a transmitter system operating in an I/Q imbalance calibration mode, comprising: a calibration signal generator for selectively generating a first in-phase calibration signal a first orthogonal calibration signal or both of the first in-phase calibration signal and the first orthogonal calibration signal; an I/Q imbalance calibrator electrically coupled to the calibration signal generator for receipt After an I/Q gain imbalance value, an I/Q gain imbalance compensation is performed on the first in-phase calibration signal and the first quadrature calibration signal to generate a second in-phase calibration signal and a second orthogonal Calibrating the signal and selectively outputting the first in-phase calibration signal, the first quadrature calibration signal, the second in-phase calibration signal, or both the second in-phase calibration signal and the second quadrature calibration signal to a front end circuit of the transmitter system; a signal strength acquisition circuit electrically connected to the front end circuit of the transmitter system for selectively acquiring and outputting one of the first to fourth calibration signal strengths, wherein The first to fourth calibration signals Corresponding to a first to fourth calibration signals, the first to fourth calibration signals are respectively processed by the front end circuit, the first in-phase calibration signal, the first orthogonal calibration signal, the second in-phase calibration signal, and the a plurality of processed signals generated by both the second in-phase calibration signal and the second orthogonal calibration signal; an I/Q imbalance estimator electrically connected to the signal strength acquisition circuit for enabling Selecting one of the first to fourth calibration signal strengths selectively by using a difference estimate, and calculating the I/Q gain imbalance value according to a first calibration signal estimated intensity and a second calibration signal estimated intensity, And calculating an I/Q phase imbalance value according to a third calibration signal estimated intensity and a fourth calibration signal estimated intensity; and the I/Q imbalance estimator further includes a difference estimator, the difference estimator Connecting the signal strength obtaining circuit to generate a reference signal strength according to an accumulated data signal, comparing the reference signal strength with one of the first to fourth calibration signal strengths, and the accumulated data signal is gradually incremented until the The reference signal strength is close to and not less than a corresponding one of the first to fourth calibration signal strengths. The I/Q imbalance calibration apparatus according to claim 1, wherein the calculation of the I/Q phase imbalance value is performed after the calculation of the I/Q gain imbalance value is performed; After the calculation of the /Q gain imbalance value, the I/Q gain imbalance value is transmitted to the I/Q imbalance calibrator to set the I/Q gain imbalance compensation value; and the I/Q phase imbalance is performed After the value is calculated, the I/Q phase imbalance value is passed to the I/Q imbalance calibrator to set the I/Q phase imbalance compensation value. The I/Q imbalance calibration device of claim 1, wherein the signal strength acquisition circuit comprises: a square calculation circuit electrically connected to the front end circuit for receiving the first to fourth calibrations One of the signals is squared; and a low pass filter is electrically connected to the squared calculation And an I/Q imbalance estimator for low pass filtering the one of the squares of the first to fourth calibration signals to generate one of the first to fourth calibration signal strengths. The I/Q imbalance calibration device of claim 1, wherein the I/Q imbalance estimator comprises: a controller electrically connected to the difference estimator, the I/Q imbalance calibration And the calibration signal generator, configured to calculate the I/Q gain imbalance value according to the first and second calibration signal estimated intensities, and calculate the I/Q phase according to the third and fourth calibration signal estimated intensities Balance value. The I/Q imbalance calibration apparatus of claim 4, wherein the difference estimator comprises: a digital analog converter electrically connected to the controller for receiving the controller according to an accumulated signal Generating the accumulated data signal, the digital analog converter is triggered by a first clock signal from the controller to perform digital analog conversion on the accumulated data signal to generate the reference signal strength; a comparator, Connecting the signal strength acquisition circuit and the digital analog converter to compare the reference signal strength with one of the first to fourth calibration signal strengths, wherein the reference signal strength is less than the first to fourth calibrations Outputting a difference signal when one of the signal strengths corresponds to one, and outputting zero when the reference signal strength is not less than a corresponding one of the first to fourth calibration signal strengths; a delay unit; An adder electrically connecting the delay unit and the comparator, wherein the delay unit is triggered by a second clock signal from the controller to delay the accumulated signal output from the adder, the adder delaying the delay An output signal of the unit is summed with an output signal of the comparator to generate the accumulated signal. The I/Q imbalance calibration apparatus of claim 1, wherein an accumulated data signal corresponding to the estimated strength of the first calibration signal is represented as M ₀ , and the estimated intensity is corresponding to the second calibration signal. The accumulated data signal is represented as M ₁ , the I/Q gain imbalance value is represented as ΔG, and ΔG=SQRT(M ₁ /M ₀ )-1; wherein the third calibration signal estimates the accumulation of the intensity The data signal is represented as K ₀ , the accumulated data signal corresponding to the estimated strength of the fourth calibration signal is represented as K ₁ , the I/Q phase imbalance value is expressed as Δθ, and Δθ=sin ^-1 { [1-(K ₁ /2K ₀ )]}.