Automatic gain control (AGC) method of radio frequency loop of TD-SCDMA (Time Division-Synchronization Code Division Multiple Access) terminal

Abstract

The invention discloses an automatic gain control (AGC) method of a radio frequency loop of a TD-SCDMA (Time Division-Synchronization Code Division Multiple Access) terminal, which comprises the following steps that (1) a wireless signal enters the radio frequency chip of the TD-SCDMA terminal, and radio frequency amplification is carried out on the wireless signal by a radio-frequency amplifier, wherein the radio frequency amplification gain is changeable; (2) mixing processing is carried out on a local oscillation signal generated by a local oscillation generating circuit and the radio frequency-amplified wireless signal to obtain a low-frequency analog signal; (3) the low-frequency signal obtained by mixing is converted into an original digital signal by an analog to digital converter after being amplified, and then power detection processing and subsequent digital gain processing are respectively carried out, wherein the analog amplification gain and the digital gain-level gain are changeable; and (4) gain control is carried out on the gain feedback process, and the digital signal with stable amplitude is input to a baseband chip. The method can increase the feedback speed of an AGC system in the TD-SCDMA terminal, reduces the errors of the feedback control and reduces the processing computation amount of the baseband chip.

Description

technical field [0001] The method of the invention relates to a signal receiving and processing method of various wireless terminals such as a mobile phone, a network card, and a netbook, and specifically relates to an automatic gain control method in a radio frequency chip of a TD-SCDMA terminal. Background technique [0002] Automatic gain control technology (AGC) is widely used in receiving electronic circuits with large-scale fluctuations in input signals. In order to cope with large-scale fluctuations in input signals, the receiving circuit should adopt an appropriate method to adjust the amplification factor and perform large-gain amplification on small-amplitude signals. , to amplify the large-amplitude signal with a small gain, so that the received signal can be unified into a small range of variation, so that the subsequent circuit can focus on the processing of the signal content and avoid the interference of excessive signal amplitude. [0003] The dynamic range o...

AI Technical Summary

Problems solved by technology

[0005] First of all, this kind of feedback control includes the receiving channel of the RF chip and the detection feedback part of the baseband chip. There are many links and large hysteresis, which cannot cope with rapid RF signal changes, such as high-speed motion applications.

Secondly, the input dynamic range of the baseband itself is limited. Quantitative judgments can be given for the signal size within its dynamic range, but qualitative judgments can only be given at most for signals above or below its dynamic range. lead to large control errors

Third, the TD-SCDMA system has its own unique characteristics. Its downlink signal is divided into time slots (TS) as receiving units, and each time slot has strong independence in a complex wireless channel environment. , the amplitude is quite different. In extreme cases, there will still be a 15-20dB change even in adjacent time slots. The baseband chip is often difficult to cope with such a rapid signal change.

Images