Common Source Amplifier with Feedback Biasing in 9Onm CMOS

Design of a high-frequency common source (CS) amplifier in 90nm CMOS suitable for use with high impedance sources is presented. High impedance sources pose challenges on the biasing of voltage amplifiers where maintaining high input impedance is necessary. To remedy this, a feedback biasing scheme is proposed. The amplifier is developed for a capacitive micromachined ultrasonic transducer (CMUT) based ultrasound system for intravenous medical imaging with a center-frequency of 100MHz and 100% bandwidth (passband: 50MHz-150MHz). The proposed amplifier achieves a voltage gain of 31.4dB, and when interfaced with the CMUT: a noise figure of 0.32dB, an SNR of 35.2dB, and THD of -35dB, while drawing 460muA from a 1V power supply