I/Q Mismatch Calibration of a Transmitter using Local Quadrature Oscillator

زارع فتین, غلامرضا and سوادی اسکویی, مصطفی and فتوت احمدی, علی (2016) I/Q Mismatch Calibration of a Transmitter using Local Quadrature Oscillator. University of Mohaghegh Ardabili, University of Mohaghegh Ardabili.

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Abstract

Abstract—In this paper a calibration technique for I/Q mismatch of a transmitter is introduced. The calibration technique is based on the fact that all mismatches in I/Q paths can be modeled as the mismatch of the local oscillator quadrature outputs. Based on this fact, a simple tuning scheme for quadrature output of the oscillator is used to calibrate the mismatch of the I/Q transmitter. In addition to quadrature oscillator, gain mismatch of the I/Q paths and LO feedthrough and leakage is calibrated by using a tunable linear Gm cell in the base band part. In order to demonstrate the proposed technique, a transmitter with 1.8 GHz carrier frequency is designed with auxiliary blocks to extract and cancel out the I/Q mismatches. The simulation results in 0.18μm RFCMOS process show that the proposed technique can reduce amplitude of the image signal resulting from mismatches in I/Q paths about 18.5 dB in the transmitter output.

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