CMOS variable-gain wide-bandwidth CMFB-free differential current feedback amplifier for ultrasound diagnostic applications

A CMOS current feedback amplifier (CFA) for ultrasound diagnostic applications is described in this paper. Unlike traditional CFA designs, this design proposes a new symmetrical circuit architecture which does not require extra common-mode feedback circuitry. The design employs active feedback to enhance the gain-bandwidth independence. Miller compensation is adopted for better frequency response and smaller on-chip capacitor. The CFA has been designed with TSMC 0.35 mum CMOS process. The active layout area is 0.052 mm 2 . HSPICE post-layout simulation shows that the CFA exhibits a bandwidth of 10.7 MHz for a variable voltage gain range of 6 dB to 60 dB, with a supply of 3.3 V and a power dissipation of 2.4 mW. Compared to CFA design without active feedback, the bandwidth variation is reduced by 8 times