Circuit and method for correcting direct current of active RC filter

Abstract

The embodiment of the invention discloses a circuit and a method for correcting the direct current of an active RC filter. The direct current can be effectively corrected by adopting the correction circuit and the correction method, wherein the method comprises the following steps of: sampling and comparing direct current signals at a positive output end and a negative output end; obtaining a digital control code by a successive approximation algorithm according to a comparison result; converting the digital control code with a D / A converter to generate a complementary analogue control signal; and adding the analogue control signal to the positive and negative input ends of the filter. Complex algorithms, such as the fast fourier transform algorithm (FFT), are not needed when the direct current is corrected and a storage space is not needed to be occupied for storing a direct current imbalance correction list, so the efficiency of correcting the direct current is improved and the structure of the correction device is simplified.

Description

technical field [0001] The invention relates to the field of radio frequency receivers, and more specifically relates to an active RC filter DC correction circuit and correction method. Background technique [0002] Filters are important blocks in RF transceivers. Active RC filters have high linearity and are commonly used in integrated RF transceivers, especially in zero-IF RF receivers and direct up-conversion transmitters. Active RC filters and other types of Filters such as transconductance-capacitor filters have distinct advantages. [0003] Zero-IF radio frequency receivers and direct up-conversion transmitters have a high degree of integration and are widely used in highly integrated radio frequency transceiver chips. But there is an important problem in zero-IF receivers: DC offset. DC offset is mainly generated in the RF front-end. DC offset will reduce the performance of the circuit. Severe DC offset will saturate the baseband circuit module of the subsequent st...

AI Technical Summary

Problems solved by technology

But there is an important problem in zero-IF receivers: DC offset

[0005] Through the research on the DC correction method in the prior art, the inventor found that: in the prior art, the feedback control signal for correcting the DC offset needs to be generated using complex algorithms such as FFT, resulting in low efficiency of the DC correction; at the same time, in the prior art Storage space is required to store the DC offset correction table, which makes the structure of the correction device of the zero-IF receiver complex

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