An Integrator-Differentiator TIA Using a Multi-Element Pseudo-Resistor in its DC Servo Loop for Enhanced Noise Performance

Abstract

In this paper, we present an integrator-differentiator transimpedance amplifier (TIA) featuring a multielement pseudo-resistor (MEPR) in the DC feedback path for improved noise performance in the presence of non-zero DC input currents. The presented prototype is implemented in a standard 180 nm CMOS technology and achieves an inband transimpedance of 10 MΩ over a 2.7 MHz signal bandwidth. The MEPR resistor in the DC servo loop can be tuned between 700 k Ω and 100 MΩ enabling a precise adjustment of the TIA's lower cutoff frequency. For a DC feedback resistance of 700 k Ω, the TIA provides an input referred noise floor of 180 fA/√Hz at zero input current, which only marginally increases to 220 fA/√Hz for the maximum bias current of 1 µA. The TIA consumes 0.6 mm2 of chip area and 18.5 mW of power from a 1.8 V supply.