A 5.3nv/rt Hz, 0.1nA Input Bias Current Amplifier with both Low and High Voltage Output Capability, Range of 4-50V, Using a BJT Input Stage with a Novel Base Current Compensation Structure

This paper presents a low-noise low-input base current amplifier with both low-voltage and high voltage output capability. The amplifier has low frequency noise and input base current by employing a BJT input stage with a novel base current compensation structure, and has low and high voltage output capability by setting the input stage of it at low voltage supply (VDDL), the third and the output stage at high voltage supply (VDDH). Simulation results show the input base current of the amplifier is around 0.1nA, and the temperature coefficient of input current is around 6pA/°C over −45°C to 125°C, the equivalent input noise of the amplifier is 5.3nV/rt Hz at 1Hz, 8.2nV/rt Hz at 0.001Hz, and the output voltage range can be from 4V to 50V with VDDL=5V, VDDH=55V. The current consumption of the amplifier is 150$\mu$A with VDDL, 450$\mu$A with VDDH. Besides, with capacitor load condition of 20pF, the bandwidth of the proposed amplifier is 24MHz, the slew rate is 11. 29MV/s. The amplifier is implemented in 180 nm BCD process. It occupies an active area of 0.504mm ² .