A nested transimpedance amplifier (TIA) circuit includes a zero-order TIA
having an input and an output, and a first operational amplifier (opamp).
The opamp includes an input that communicates with said output of said
zero-order TIA, a first transistor driven by said input, a second
transistor that is driven by a first bias voltage and communicates with
said first transistor, a first current source that communicates with said
second transistor, and an output at a node between the first transistor
and the second transistor.