Device and method for adaptive correction of orthogonal unbalance

Abstract

The invention relates to a device used in adaptable orthogonal imbalance correction and relative method, which can correct the orthogonal imbalance signal received by receiver, to eliminate orthogonal imbalance. Wherein, said method comprises that first calculating out the interference of phase-same signal on the positive-phase signal after orthogonal imbalance; reducing the interference to obtain the corrected positive-phase signal without imbalance phase; comparing the powers of phase-same signals, outputting the power of positive-phase signal, outputting the difference from target value, to decide the phase-same zoom times and positive-phase zoom times; at least, multiplying the phase-same signal with phase-same zoom times to obtain the output phase-same signal, and multiplying said corrected signal with positive-phase zoom times to obtain output positive-phase signal.

Description

technical field [0001] The invention relates to a device and method for correcting quadrature imbalance, especially a device and method for adaptively correcting quadrature imbalance. Background technique [0002] The current direct conversion receiver (receiver) has lower power consumption and better integration, so most of today's portable (potable) wireless communication systems adopt this architecture to achieve power saving with the purpose of reducing the size. However, this architecture must overcome the influence caused by quadrature imbalance (I / Q imbalance). As shown in Figure 1, for the in-phase signal I (in-phase signal) and the non-phase signal Q (quadrature signal), quadrature imbalance includes two phenomena: phase imbalance (θ) and amplitude imbalance (amplitude imbalance, ε). Due to this unbalanced phenomenon, the phase difference between the in-phase signal I' and the normal-phase signal Q' after the quadrature imbalance cannot maintain the 90-degree quad...

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Problems solved by technology

For example, in the European digital TV (DVB-T / DVB-H) specification, if the phase imbalance is greater than 5 degrees and the amplitude imbalance is greater than 1dB, the error rate (Bit Error Rate) of the entire system will exceed the standard

In addition, the quadrature imbalance will change due to the temperature, time, and the selected frequency band; therefore, the traditional method of using calibration signals to correct the quadrature imbalance will change due to the change of the quadrature imbalance. fail

[0004] Among patent literatures known to address quadrature imbalance, U.S. Patent No. 5,321,726 "Calibration of vector demodulator using statistical analysis" to K. Kafada and U.S. Patent No. 5,369,411 "Imbalance correction of in-phase "andquadrature phase return signals" is to use a set of calibration signals (calibration signals) to estimate the value of the imbalance, and then correct it. Therefore, when the quadrature imbalance changes with temperature, time, and the selected frequency band, The aforementioned method cannot be corrected in time

[0005] The U.S. Patent No.5,105,195 "System and method for compensation of in-phase and quadrature phase and gain imbalance" granted to J.C.Conrad uses FFT to convert the signal to the frequency domain (frequency domain) to correct the quadrature imbalance, but it only Suitable for OFDM systems, if you want to use a non-OFDM system, you need an additional FFT circuit

However, although the method for correcting quadrature imbalances adopted in the U.S. Patent No. 6,044,112 "Method and apparatus for correcting amplitude and phase imbalances in demodulators" issued to J.L.Koslov can be corrected over time, it can only be used in single carrier (single carrier) used in communication systems

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