Patent ID: 6785392
Filing Date: 2004-08-31
Classification: H03F

Abstract:
A circuit for enabling and disabling an amplifier, the amplifier having a signal level associated therewith, the circuit comprising:a gain stage for amplifying the signal level and generating an amplified signal level; threshold circuitry for comparing the amplified signal level to a plurality of thresholds and indicating a signal level state representative of the amplified signal level; and control circuitry for enabling and disabling the amplifier in response to the signal level state, the control circuitry comprising adjustment circuitry coupled between the threshold circuitry and the gain stage for introducing discrete signal level adjustments to the amplified signal level in opposition to a change in the amplified signal level indicated by a corresponding change in the signal level state, thereby opposing drift in the amplified signal level, wherein the control circuitry further comprises qualification circuitry for qualifying enablement of the amplifier where the amplified signal level is between the first and second values, the control circuitry being operable to enable the amplifier without regard to the qualification circuitry where the amplified signal level exceeds the second value.