Orthogonal mismatch calibration method and device of direct frequency conversion transmitter

Abstract

The invention relates to an orthogonal mismatch calibration method and device of a direct frequency conversion transmitter. The orthogonal mismatch calibration device comprises a first voltage comparator, a second voltage comparator, a first switching circuit, a second switching circuit, a digital state machine, a low-pass filter, a gain fine-tuning circuit and a phase fine-tuning circuit. The output end of a passive frequency mixer is connected with the input end of the low-pass filter, and the output end of the low-pass filter is connected with a first input end of the second voltage comparator. The gain error and the phase error between same-phase / orthogonal channels of the direct frequency conversion transmitter are measured with the orthogonal mismatch calibration method and device; the optimal calibration value is obtained through successive approximation, the self-calibration capacity of orthogonal mismatch of the direct frequency conversion transmitter can be improved, and dependency, complexity and power consumption of a calibration system are lowered.

Description

Technical field [0001] The invention relates to a method and device for quadrature mismatch calibration of a direct frequency conversion transmitter. Background technique [0002] Among wireless communication transmitters, direct conversion transmitters are widely used in the field of radio frequency integrated circuits because of their simple circuit structure and ease of integration. Direct conversion transmitters that use passive mixers with a 25% duty cycle local oscillator have gradually become mainstream technologies due to their high linearity, low noise, and low power consumption. However, the quadrature mismatch problem in the direct conversion transmission architecture has always been one of its main defects. The image interference of the transmitted signal caused by the mismatch makes the quality of the transmitted signal worse. Direct conversion transmitters must be calibrated for quadrature mismatch. [0003] in figure 1 with figure 2 The typical direct conversion ...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to propose a method and device for calibrating quadrature mismatch of a direct conversion transmitter, which can solve the problems of large amount of calculation, many components involved in calibration, and large power consumption.

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