A switching threshold programmable high-linearity transimpedance amplifier for OLED pixel current mismatch measurement

In this paper, we present a new switching threshold programmable transimpedance amplifier (TIA) for OLED pixel current measurement system. The TIA is composed of an inverter-based cascode amplifier that achieves DC gain of 87 dB for high linearity. To maximize the current efficiency, novel biasing scheme using series capacitor between two input transconductors is proposed so that the current efficiency of NMOS and PMOS transistors are individually maximized. In order to correct random source voltage variation, the switching threshold range is adjustable with 4-bit resolution implemented in 180 nm CMOS technology, the prototype TIA achieves 4% of current-to-voltage conversion linearity error and 23 mV of switching threshold adjustment range. The implemented differential TIA consumes 165 μW under 3.3 V when operating at 5.2 kHz.