Direct Conversion Receiver with DC Offset Compensation Function and Its Compensation Method

Abstract

The present invention provides a direct conversion receiver with a DC offset compensation function, including an antenna, a mixer module, an automatic gain control amplifier, an adder, a DC offset elimination circuit, a track and hold circuit and a switch circuit. The antenna receives a radio frequency signal with a carrier frequency. The mixer module converts the RF signal to a baseband signal. An automatic gain control amplifier amplifies the fundamental frequency signal. The adder subtracts the DC offset current from the fundamental frequency signal. The DC offset elimination circuit obtains the DC offset value in the digital signal and converts it into a DC offset current. The track and hold circuit receives the fundamental frequency signal, maintains the DC offset voltage on the capacitor, and converts it into a DC offset current. The switching circuit alternately switches the DC offset elimination circuit and the tracking and holding circuit to receive the fundamental frequency signal.

Description

Technical field [0001] The invention relates to a direct conversion receiver, in particular to a direct conversion receiver with a DC offset compensation function used in a mobile phone. Background technique [0002] In a digital communication system, the transmitted signal is generated by mixing digital data with a carrier after being modulated. Digital signals are usually transmitted in bursts, and each burst contains multiple data bits. When the transmitted signal is received, it must go through a step of demodulation to get the data back. [0003] The basic architecture of a wireless receiver usually uses a direct conversion receiver to demodulate the received signal. It uses a local oscillator with the same carrier frequency to down-convert the received signal to generate in-phase and quadrature fundamental frequency signals. The direct conversion receiver has the advantages of low cost and low energy consumption. The main purpose of direct frequency reduction is to direct...

AI Technical Summary

Problems solved by technology

[0011] However, due to the long charging time of the capacitor in the track and hold circuit, the above-mentioned receiver needs a long time to complete the compensation of the DC offset

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