This paper presents a linear-mode optical sensor for the feasible applications of unmanned vehicle LiDAR systems, in which a pulsed-erbium fiber laser is exploited as a light source and a 16-channel transimpedance amplifier (TIA) array is utilized in an optical Rx module with low-cost InGaAs PIN photodiodes. In particular, a voltage-mode CMOS feedforward (VCF-TIA) is newly proposed to achieve twice higher transimpedance gain with lower noise and similar bandwidth characteristics than a conventional inverter TIA, thereby enabling longer detection. Test chips of the 16-channel VCF-TIA array realized in a standard 0.18-μm CMOS process demonstrate 76.3-dBΩ transimpedance gain, 6.3-pA/sqrt(Hz) average noise current spectral density, less than -33-dB crosstalk between channels, and 29.8-mW power dissipation per channel from a single 1.8-V supply. Automatic gain control is also equipped to extend input dynamic range for near-range detection. Hence, the proposed linear-mode optical sensor clearly detects the reflected optical pulses from the target of 5% reflection rate within the range of 0.5-25 m.

This paper presents a current mode transimpedance amplifier (TIA) implemented in a standard 65-nm CMOS technology for the applications of elder-care home monitoring LiDAR sensors. Particularly, a novel mirrored current–conveyor (MCC) input configuration is proposed to lower the input impedance, thus achieving a wide bandwidth. This MCC-TIA can alleviate severe pulse spreading issue for near-range detection, enabling effective narrow-pulse recovery. Also, a feedforward control-voltage generator is newly suggested to realize an automatic gain-control within a single pulse-width duration. Measured results demonstrate the variable transimpedance gain of 59~77 dBΩ to accommodate the incoming input currents of 18 μApp ~ 2.24 mApp that corresponds to the feasible detection range of 0.5~5.3 meters in an elder’s home. The bandwidth of 83 MHz~2.6 GHz is measured with the minimum noise current spectral density of 16.8 pA/sqrt(Hz). The chip dissipates 40 mW in total, and occupies the area of 1.0 mm2, including I/O pads.

This paper presents an optoelectronic receiver (Rx) IC with an on-chip avalanche photodiode (APD) realized in a 0.18-μm CMOS process for the applications of home-monitoring light detection and ranging (LiDAR) sensors, where the on-chip CMOS P⁺/N-well APD was implemented to avoid the unwanted signal distortion from bondwires and electro-static discharge (ESD) protection diodes. Various circuit techniques are exploited in this work, such as the feedforward transimpedance amplifier for high gain, and a limiting amplifier with negative impedance compensation for wide bandwidth. Measured results demonstrate 93.4-dBΩ transimpedance gain, 790-MHz bandwidth, 12-pA/√Hz noise current spectral density, 6.74-μA_pp minimum detectable signal that corresponds to the maximum detection range of 10 m, and 56.5-mW power dissipation from a 1.8-V supply. This optoelectronic Rx IC provides a potential for a low-cost low-power solution in the applications of home-monitoring LiDAR sensors.

This paper presents an optoelectronic receiver IC with on-chip avalanche photodiode (APD) realized in a 180-nm CMOS process for the applications of indoor-monitoring light detection and ranging (LiDAR) sensors. As an on-chip optical detector, a CMOS P+/N-well APD is integrated, thereby enabling to avoid unwanted signal distortion from bond-wires and ESD protection diodes. Various circuit techniques are exploited in this work, including the dual-feedback folded-cascode differential transimpedance amplifier (DFD-TIA) to achieve fully differential signaling from the input stage, an active single-to-differential converter to minimize the inherent mismatches of the preceding DFD-TIA, a cross-coupled inverter-based post-amplifier to improve the symmetry of the output voltage swings, and a two-stage differential amplifier with negative impedance compensation to obtain gain-boosting and wide bandwidth characteristics. Measured results of the proposed optoelectronic receiver IC demonstrates 87-dBΩ transimpedance gain, 577-MHz bandwidth, 15.4-pA/√Hz noise current spectral density, 4.18-μA _pp minimum detectable signal that corresponds to the maximum detection range of 10 meters, and 50.6-mW power dissipation from a 1.8-V supply. Optical measurements utilizing an 850-nm laser diode with the average power of 10 mW reveal that the proposed optoelectronic receiver IC successfully recovers narrow 1-ns light pulses with the full-width at half maximum (FHWM) of 840 ps even at the short distance of 50 centimeters. Hence, this work provides a potential solution for low-cost, low-power short-range LiDAR sensors.

This paper introduces an indoor-monitoring LiDAR sensor for patients with Alzheimer disease residing in long-term care facilities (LTCFs), and this sensor exploits an optoelectronic analog front-end (AFE) to detect light signals from targets by utilizing on-chip avalanche photodiodes (APDs) realized in a 180 nm CMOS process and a neural processing unit (NPU) used for motion detection and decisions, especially for incidents of falls occurring in LTCFs. The AFE consists of an on-chip CMOS P⁺/N-well APD, a linear-mode transimpedance amplifier, a post-amplifier, and a time-to-digital converter, whereas the NPU exploits network sparsity and approximate processing elements for low-power operation. This work provides a potential solution of low-cost, low-power, indoor-monitoring LiDAR sensors for patients with Alzheimer disease in LTCFs.