In chopper amplifiers, the interaction between the input signal and the chopper clock can give rise to intermodulation distortion (IMD). This chopper-induced IMD is mainly due to amplifier delay, which causes large pulses at the output of the amplifier's output chopper. This paper proposes the use of a socalled fill-in technique to eliminate these pulses, and thus the resulting IMD, by multiplexing the outputs of two identical amplifiers that are chopped in quadrature. A prototype chopperstabilized amplifier was implemented in a 180nm CMOS process. Measurements show that the fill-in technique suppresses chopperinduced IMD by 28 dB, resulting in an IMD of -126 dB for input frequencies near 4FCH (= 80 kHz). It also improves the amplifier's two-tone IMD (with 79 & 80 kHz inputs) from -97 dB to -107 dB, which is the same as that obtained without chopping.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.