CMOS Low-Power Variable-Gain CMFB-Free Current Feedback Amplifier for Ultrasound Diagnostic Applications

A CMOS current feedback amplifier (CFA) for ultrasound diagnostic applications is proposed. Unlike traditional CFAs, this design employs a new symmetrical and compact architecture, without the use of common-mode feedback (CMFB) circuitry. The design proposes an active feedback technique to drastically enhance the gain-bandwidth independence. It is also the first CFA to adopt Miller compensation for better frequency response with smaller compensation capacitor. The proposed CFA was fabricated and tested with a standard 0.35 mum CMOS process with competitive performance to its Bipolar and BiCMOS counterparts. The active die area is 0.052 mm2. Experiment results show that the CFA exhibits a minimum bandwidth of 4.5 MHz with a variable gain range of 0 to 46 dB, and a power dissipation of 2.18 mW.