A wideband complementary noise and distortion canceling LNA for high-frequency ultrasound imaging applications

Abstract

This paper presents a simultaneous noise and distortion canceling low noise amplifier (LNA) for high-frequency ultrasound imaging applications. A feedforward noise canceling technique is developed to achieve both low noise figure (NF) and good input impedance matching (S11). The LNA also exploits the complementary characteristics of NMOS and PMOS transistors to cancel the second-order harmonic for linearity enhancement. The proposed LNA is designed in a 0.18 μm CMOS technology and exhibits a 6 dB NF and a 10 dB total harmonic distortion (THD) improvements. The LNA is specifically designed for 30–120 MHz high-frequency ultrasound transducers. At 30 MHz, the LNA achieves a NF of 2.1 dB, a voltage gain of 19 dB, and a THD of 60 dB under 1 mV peak-to-peak input. The core circuit draws 10 mA current from a 1.8 V supply.