Iq mismatch correction for zero-if/low-if tx/rx

Abstract

IQ mismatch correction for analog chain IQ mismatch impairments is based on a two-filter architecture. In either RX or TX, an IQmc mismatch corrector (digital chain) filters I and Q digital signals, and includes an I-path to receive the I signal, and a Q-path to receive the Q signal, and is configured with two filters: an in-path filter to filter either the I signal or the Q signal received in the same path; and a cross-path filter to filter either the I signal or the Q signal received in the other path. The IQmc mismatch corrector can include: an I-path delay element to provide a delay to the I signal corresponding to a delay through either the in-path filter or the cross-path filter; and a Q-path delay element to provide a delay to the Q signal corresponding to a delay through either the in-path filter or the cross-path filter.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Priority is claimed under 37 CFR 1.78 and 35 USC 119(e) to INDIA Provisional Application 2018 / 41012763 (Docket TI-78469P5), filed 2018 Apr. 4, which is incorporated by reference in its entirety.BACKGROUND[0002]Wireless infrastructure can employ zero-IF and low-intermediate frequency (zero / low-IF) architectures for TX and RX. An analog signal chain provides RF TX / RX, and a digital signal chain operates at baseband, commonly with DUC / DDC (digital upconversion / downconversion). The analog chain implements complex, quadrature (IQ) modulation / demodulation. The analog and digital signal chains are interfaced with a TX DAC or RX ADC.[0003]The analog IQ chain includes a complex IQ modulator (TX), or demodulator (RX). Mismatches between the I and Q signal chains (IQ errors) include frequency independent gain / phase mismatch in the local oscillators, and frequency dependent mismatch errors in mixers and filter transfer functions, and delay errors thr...

AI Technical Summary

Benefits of technology

The patent describes a method and apparatus for improving the quality of signals transmitted in RF communication systems. It introduces a two-filter architecture to correct IQ mismatches, which can be introduced by the analog circuitry of the system. The apparatus includes filters to introduce IQ mismatch impairments and an IQ mismatch corrector to filter the signals and provide correction. The method involves receiving the signals, filtering them using the corrector, and introducing a delay to either the in-path or cross-path filter element to correct the impairments. The technical effects of this invention include improved signal quality, reduced interference, and improved transmission distance.

Problems solved by technology

Mismatches between the I and Q signal chains (IQ errors) include frequency independent gain / phase mismatch in the local oscillators, and frequency dependent mismatch errors in mixers and filter transfer functions, and delay errors through the I and Q signal paths.

These I / Q mismatch errors lead to side-band leakage (I / Q imbalance).

Images