1) "A DC to 1 GHz Differential Monolithic Variable Gain Amplifier" by R. Meyer et. al., JSSC, Nov. 1991.
2) "A Single-Chip Bipolar AGC Amplifier with Large Dynamic Range for Optical Fibre Receivers Operating up to 3 Gb/s" by R. Reimann et. al., JSSC, Dec. 1989.