A high performance CMOS feedforward AGC circuit for wideband wireless receivers

This paper presents a fast settling compact feedforward automatic gain control (AGC) suitable for use in wireless communication systems such as WLAN or Bluetooth receivers where the use of traditional closed loop feedback amplifiers forms a boundary due to the stringent settling time constraints. The AGC has been implemented in a 0.35 mum standard CMOS technology. Supplied at 1.8 V, it operates with a power consumption of 1.6 mW at frequencies as high as 100 MHz, while its gain ranges from 0 to 21 dB in 3 dB steps through a 4-bit word. The settling time of the circuit is below 0.25 mus.