A Low Power, Low Noise, Single-Ended to Differential TIA for Ultrasound Imaging Probes

This brief presents a low power low noise amplifier (LNA) in TSMC 0.18 mu m CMOS technology for ultrasound imaging probes. The proposed LNA is based on a trans-impedance amplifier (TIA). Single-ended to differential conversion is realized using a common-gate and a common-source (CG-CS) based structure. Resistive feedback is exploited to provide a noise canceling scheme for the CS transistor. Unlike the conventional CG-CS structure that can only eliminate the noise of the CG transistor, the proposed structure eliminates the noise of both CG and CS transistors as well as the CG stage load resistor. Furthermore, by using negative feedback in the CG stage and current reuse technique in both stages, power consumption is reduced. Post-layout simulation results show a trans-impedance gain of 82 dB Omega with a -3 dB bandwidth of 77 MHz, while input impedance is 731 Omega. The second harmonic distortion (HD2) is lower than -48.5 dB and the equivalent input referred noise is 1.95 pA/root Hz at 5 MHz. The circuit occupies an active area of 312 mu m(2) and consumes 47 mu W from a 1.2 V supply.