This paper presents a new automatic gain control main amplifier for 10GBase-LX4 Ethernet realized in a 0.18 μm
CMOS process. The proposed optical-fiber differential post-amplifier is based on a very compact inductorless design
which comprises three main digitally programmable gain stages followed by a buffer. It is characterized by a -3 dB
cutoff frequency above 3 GHz over a -3 to 33 dB linear-in-dB gain control. It includes a DC offset cancellation
network and an automatic gain control loop which establishes a setting time below 1μs. Results show a sensitivity of
2.1 mV for BER = 10<sup>-12</sup> and an input dynamic range above 50 dB. The power consumption is 58 mW at a single supply
voltage of 1.8 V.