Automatic gain control with improved cross-modulation

Abstract

An apparatus (100) such as a television signal receiver provides an AGC function which reduces cross-modulation distortion. According to an exemplary embodiment, the apparatus (100) includes a source of an input signal and a gain control circuit (60) coupled to the source of the input signal. The gain control circuit (60) provides a first control signal (RF AGC) at a first level to a first amplifier (10) while a magnitude of the input signal is within a first range and provides the first control signal (RF AGC) at a second level to the first amplifier (10) while the magnitude of the input signal is within a second range.

Description

Technical field [0001] The present invention generally relates to automatic gain control (AGC) of devices such as television signal receivers, and more particularly, to a device and method that provide an AGC function that reduces cross-modulation distortion. Background technique [0002] Various devices such as television signal receivers include AGC functions to maintain sufficient performance within the input signal level range. Certain devices use AGC functions for radio frequency (RF) and intermediate frequency (IF) signals. Splitting the AGC function into the RF and IF parts in this way can be beneficial to provide the desired performance in terms of noise figure and anti-interference. [0003] Using traditional devices that split the AGC function into RF and IF parts, the IF AGC usually starts operation first to control the IF gain until the established input signal strength is obtained. After the established input signal strength is obtained, RFAGC starts operation, and t...

AI Technical Summary

Problems solved by technology

In particular, use of such conventional AGC control schemes in tuner applications using dual-gate MOSFETs tends to produce undesired amounts of cross-modulation distortion

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