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

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 (S
₁₁
). 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.