A 170-dB $\Omega $ CMOS TIA With 52-pA Input-Referred Noise and 1-MHz Bandwidth for Very Low Current Sensing

A fully integrated current sensing interface chip employing a capacitive-feedback transimpedance amplifier (TIA) is presented. A robust dc current removal block is proposed to prevent the dc portion of the input current from saturating the output voltage. This block allows the TIA to operate in the presence of a wide range of input dc currents, and the cancellation loop is designed to enhance its stability. The TIA is fully integrated in a standard 0.13 μm CMOS technology, and a gain of 170 dBΩ is achieved without requiring any off-chip resistors. The integrated input-referred current noise of the interface circuit is 0.4, 3.8, and 52 pARMS within 0.01, 0.1, and 1 MHz integration bandwidths, respectively.