Design of Low-Power and High-Frequency Switched-Opamp Circuits

Abstract

In 1994, switched-opamp (SO) technique [CRO 94] has been shown to be a promising low-cost solution to realize SC circuits at 1-V in standard CMOS processes. Since then, a few numbers of modifications [BAS 97a, CHE 00b] have been proposed to improve the performance of the switched-opamp technique in terms of operation speed and compatibility with most of the existing SC systems. Yet, SC circuits employing those switched-opamp techniques at 1-V operation can only achieve a reported operation speed up to 10 MHz, which is far lower than the SC circuits at higher voltages. This chapter focuses on the development of switched-opamp circuits, on both system-level and circuit-level, to handle with both low power and high frequency applications. Up to 50 MHz of operation speed was measured through the demonstration of a 1-V 10.7-MHz CMOS switched-opamp bandpass ΣΔ modulator [CHE 02b].