A Dual-Mode Adjustable High-Gain Ultra-Low Noise Transimpedance Amplifier for Fine Dust Detection

This paper presents a dual-mode adjustable-high-gain transimpedance amplifier (TIA). The TIA is designed with a high sensitivity to current bio-signals for a fine-dust detection system Integrated Circuit (IC) based on the operation of a photodiode module with high gain amplifications. Gain adjustment is implemented by coarse gain steps using selective-loads with four different gain values and fine gain steps by 42 dBΩ during 16 fine steps. To improve the settling time, a capacitive compensation is applied for the last stage. An off-state circuitry is proposed to avoid any off-current leakage. This TIA is designed in a 0.18 μm standard CMOS technology, output reached high gains from 149 dBΩ up to 216 dBΩ with 67 dBΩ gain variation range, input referred noise less than 600 fA/√ Hz in low frequencies and less then 27 fA/√ Hz at 20 KHz, a minimum detectable current signal of 4 pA, and has a power consumption of 2.71 mW.