A digital automatic gain control (AGC) circuit for use in a radio frequency (RF)
receiver. The AGC circuit comprises: 1) a first shifter for receiving an in-phase
signal as a first series of X-bit samples and left-shifting each X-bit sample by
a number of bits determined by a coarse scaling factor; 2) a first limiter for
receiving the D most significant bits of the output of the first shifter and outputting
a subset of the D most significant bits of the first shifter output; 3) a first
multiplier for multiplying the subset of the D most significant bits of the first
shifter output by a fine scaling factor to produce a first M-bit product; and 4)
a gain adjustment circuit for comparing a power signal derived from the first M-bit
product to a maximum threshold value and generating the coarse scaling factor and
the fine scaling factor.