Patent ID: 6404829
Filing Date: 2002-06-11
Classification: G11B

Abstract:
An automatic gain control circuit (AGC) for an optical Partial Response Maximum Likelihood (PRML) read channel that is insensitive to low frequency disturbances of an RF input signal comprising:a. a Voltage Gain Amplifier (VGA) for amplifying the RF input signal to produce a second RF signal, a gain of the VGA being controlled by an analog gain control signal; b. a low pass filter for filtering the second RF signal to produce a first analog signal; c. an Analog-to-Digital Converter (ADC) for converting the first analog signal into a digital AGC output signal suitable for decoding; d. a baseline Wander Correction Circuit for removing from the digital AGC output signal effects of low frequency disturbance of the RF input signal to produce a second digital signal; e. a digital gain control circuit for controlling the gain of the VGA by producing a digital gain control signal in response to the second digital signal; and f. a Digital-to-Analog Converter (DAC) for converting the digital gain control signal into the analog gain control signal, the analog gain control signal being substantially free from effects of low frequency disturbance of the RF input signal.