Novel gₘ-boosted high gain transimpedance amplifiers for biomedical and sensor applications in 180nm CMOS technology : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Electronics and Computer Engineering at School of Engineering and Advanced Technology, Massey University, Albany Campus

Abstract

This research work introduces five novel gₘ-boosted transimpedance amplifiers (TIAs), which are (1) a gₘ-boosted common-source with source-degeneration as a TIA, (2) a gₘ-boosted inverter cascode TIA (gₘ-boosted Inv-Cas TIA) using quasi-floating gate (QFG), (3) a gₘ-boosted folded regulated cascode TIA (gₘ-boosted RIC TIA) using QFG, (4) a gₘ-boosted doubly folded push-pull TIA and (5) a gₘ-boosted multiple-stage inductively peaked TIA. The transimpedance gain analysis is discussed for all the proposed TIAs. And the input referred noise power current spectral density of the last four topologies have been developed mathematically in this thesis. To demonstrate actual performance enhancement achieved circuit simulation results are also provided as verification. Each TIA is simulated with a 5 pF photodiode (PD) input capacitance and a 500 fF output capacitance. The simulation analysis consists of (1) a transient response of output voltage, (2) a transimpedance gain, (3) a -3 dB bandwidth, (4) an input referred noise current power spectral density, and (5) an eye diagram simulation using a 231-1 pseudo random bit sequence (PRBS) data pattern as an input. A test chip implementing the gₘ-boosted Inv-Cas TIA, gₘ-boosted RIC TIA, and gₘ-boosted multiple-stage inductively peaked TIA was fabricated using a 180nm CMOS process. Also, the microchip was tested by using a fabricated PCB and giving sinusoidal and square wave inputs. Finally, a detailed discussion is given on the experimental results section.