A Mixed-Signal Integrator-Differentiator-TIA

Various implementations of transimpedance amplifiers (TIAs) are used for current sensing applications and they allow for low noise and wide bandwidth (BW). The process of digitization is usually not implicitly discussed. Though, BW limitation, sampling and quantization obviously add additional circuit complexity and have a strong influence on the minimum achievable spot-noise in low noise TIAs. We introduce a mixed-signal topology for the integrator-differentiator TIA (I-D-TIA), which introduces the analog-to-digital converter (ADC) before differentiation, thereby avoiding the implementation of the usually wideband and power-dominating analog differentiator. The proposed topologies are compared by circuit-level simulations.