Patent ID: 7697644

Claim:
A system for performing stepped automatic gain control (AGC) for orthogonal-frequency-division-multiplexing (OFDM) applications, said system comprising: a radio frequency (RF) tuner comprising: a variable gain low noise amplifier (LNA) adapted to amplify a RF signal being input into said RF tuner; a local oscillator adapted to generate a signal carrier; a mixer operatively connected to said LNA and said local oscillator, wherein said mixer is adapted to mix said RF signal with said signal carrier to create a baseband signal; a filter operatively connected to said mixer, wherein said filter is adapted to filter said baseband signal; and a variable gain amplifier (VGA) operatively connected to said filter, wherein said VGA is adapted to amplify the filtered baseband signal; an OFDM demodulator operatively connected to said RF tuner, said OFDM demodulator comprising logic circuitry adapted to (i) detect OFDM symbols from a stream of data; (ii) detect boundaries of said OFDM symbols; (iii) detect a cyclic prefix duration of data values associated with said OFDM symbols; and (iv) provide a feedback to said RF tuner of said information pertaining to said boundaries of said OFDM symbols and said cyclic prefix duration, wherein said LNA and said VGA are each adapted to use information pertaining to said boundaries of said OFDM symbols to change a stepped gain in each of said LNA and said VGA only during said cyclic prefix duration.