Inverter-based 1V transimpedance amplifier in 90nm CMOS for medical ultrasound imaging

In this paper, we propose a 1V transimpedance amplifier design based on an inverter based cascode amplifier as opposed to the conventional transimpedance amplifier based on an Operational Transconductance Amplifier (OTA). The proposed amplifier is designed to amplify the signals from Capacitive Micro machined Ultrasound Transducers (CMUTs) in the frequency bandwidth from 15MHz to 45MHz with a center frequency of 30MHz for medical ultrasound imaging systems. From the measurements, the proposed single-ended transimpedance amplifier achieves a voltage gain of 18.9 dB, an output noise power spectral density of 0.0421 (µV)/SQRT(Hz) at a center-frequency of 30 MHz, and a total harmonic distortion of −23.16 dB, at 450mV p-p output voltage at 30 MHz input signal frequency. It draws only 598 µA current per amplifier from a 1-V power supply. The proposed single-ended trans-impedance amplifier was fabricated in a 90-nm CMOS technology and it's area measured to be about 32.4 µm × 32.4 µm only per amplifier.