A Complementary Metal-Oxide-Semiconductor Optoelectronic Analog Front-End Preamplifier with Cross-Coupled Active Loads for Short-Range LiDARs

In this paper, a CMOS optoelectronic analog front-end (AFE) preamplifier with cross-coupled active loads for short range LiDAR applications is presented, which consists of a spatially modulated P⁺/N-well on-chip avalanche photodiode (APD), the differential input stage with cross-coupled active loads, and an output buffer. Particularly, another on-chip dummy APD is inserted at the differential input node to improve the common-mode noise rejection ratio significantly better than conventional single-ended TIAs. Moreover, the cross-coupled active loads are exploited at the output nodes of the preamplifier not only to help generate symmetric output waveforms, but also to enable the limiting operations even without the following post-amplifiers. In addition, the inductive behavior of the cross-coupled active loads extends the bandwidth further. The proposed AFE preamplifier implemented in a 180-nm CMOS process demonstrate the measured results of 63.5 dB dynamic range (i.e., 1 µA_pp~1.5 mA_pp input current recovery), 67.8 dBΩ transimpedance gain, 1.6 GHz bandwidth for the APD capacitance of 490 fF, 6.83 pA⁄√Hz noise current spectral density, 85 dB power supply rejection ratio, and 32.4 mW power dissipation from a single 1.8 V supply. The chip core occupies the area of 206 × 150 µm².