Design of a low-power 3.5-GHz broad-band CMOS transimpedance amplifier for optical transceivers

This paper describes a novel low-power low-noise CMOS voltage-current feedback transimpedance amplifier design using a low-cost Agilent 0.5-μm 3M1P CMOS process technology. Theoretical foundations for this transimpedance amplifier by way of gain, bandwidth and noise analysis are developed. The bandwidth of the amplifier was extended using the inductive peaking technique, and, simulation results indicated a -3-dB bandwidth of 3.5 GHz with a transimpedance gain of ≈60 dBohms. The dynamic range of the amplifier was wide enough to enable an output peak-to-peak voltage swing of around 400 mV for a test input current swing of 100 μA. The output noise voltage spectral density was 12 nV/√Hz (with a peak of ≈25 nV/√Hz), while the input-referred noise current spectral density was below 20 pA/√Hz within the amplifier frequency band. The amplifier consumes only around 5 mA from a 3.3-V power supply. A test chip implementing the transimpedance amplifier was also fabricated using the low-cost CMOS process.