A Fast-Recovery Transimpedance Amplifier with Ambient Light Cancellation for Automotive LiDAR Systems

To address the challenges of ambient light interference and slow overload recovery in transimpedance amplifiers (TIAs) for automotive Light Detection and Ranging (LiDAR) systems, this paper proposes a high-performance TIA with integrated ambient light cancellation and fast recovery capabilities. The core design includes an adaptive ambient light cancellation (ALC) loop that eliminates background currents up to 3 mA without relying on AC coupling capacitors, achieving a low-frequency cutoff frequency of 321 kHz to ensure the signal-to-noise ratio (SNR) of weak target signals. A multi-stage clamping and current transfer mechanism is employed to realize rapid overload recovery: under 100 mA heavy overload conditions, the recovery time is controlled within 8.7 ns, and the pulse broadening is limited to 2.7 ns, avoiding measurement blind zones. Implemented in a 0.18-$\mu$m SiGe BiCMOS process, the proposed TIA occupies a compact area of 0.15 mm^2, with a transimpedance gain of 80 dB$\Omega$ (10 kΩ) and a -3 dB bandwidth of 421 MHz. The input-referred noise current spectral density is 4.7 pA/√Hz, and the integrated equivalent input noise current from 1 Hz to 250 MHz is 73.6 nArms. Operating over a temperature range of -40 ℃ to 125 ℃, the TIA meets the rigorous requirements of automotive-grade applications. Performance comparisons with commercial products and state-of-the-art designs validate its superior ambient light rejection and fast recovery performance, making it suitable for direct time-of-flight (dToF) LiDAR systems in autonomous driving.