A simple approach for the implementation of CMOS amplifiers with constant bandwidth independent of gain

In this paper we discuss an efficient implementation of the Cherry-Hooper amplifier scheme based on a new OTA structure. This is used to design highly linear CMOS amplifiers with programmable and accurate gain and high bandwidth that remains approximately constant with gain adjustment. A fully differential VGA with 30 MHz approximate constant bandwidth and accurate digitally adjustable gain from 1 to 128 in 0.5 mum CMOS technology is discussed. Experimental verification of the proposed scheme is also provided.