Phase rotator for compensating transceiver impairments

摘要

A phase rotator corrects the IQ imbalance in a wireless transceiver. The phase rotator is a part of a compensation system that detects and separates reception impairment images from transmission impairment images. The disclosed phase rotator introduces a phase shift between the transmission channel and the reception channel without perturbing the phase mismatch and the gain mismatch in the reception path. The phase rotator includes a first local oscillation (LO) circuit that generates a first LO signal at a first carrier frequency and a second LO circuit that generates a second LO signal at a second carrier frequency that deviates from the first carrier frequency for a phase rotation period. The phase rotation period is sufficiently long such that the frequency deviation can introduce a prescribed phase shift between the first LO signal and the second LO signal.

主权项

1. An integrated circuit comprising:
a first local oscillation (LO) circuit configured to generate a first LO signal having a first carrier frequency; a first mixer coupled with the first LO circuit, the first mixer configured to up-convert a baseband signal to a transmission radio frequency (RF) signal based on the first carrier frequency of the first LO signal; a second LO circuit configured to generate a second LO signal having a second carrier frequency deviating from the first carrier frequency for a phase rotation period sufficient to introduce a phase shift between the first LO signal and the second LO signal; a second mixer coupled with the second LO circuit, the second mixer configured to down-convert a reception RF signal based on the second LO signal outside of the phase rotation period; and a switching circuit having a first input, a second input, and an output, the first input coupled to the first LO circuit, the second input coupled to the second LO circuit, and the output coupled to the second mixer.