Abstract
Amplifiers often employ chopping to achieve low offset and low-frequency noise. However, the interaction between the input signal and the chopper clock can cause chopper-induced intermodulation distortion (IMD) [1] -[5]. This is especially problematic for input frequencies (Fin) near even multiples of the chopping frequency (FCH), as the resulting IMD tones fold-back to low frequencies and so cannot be filtered out. In [2] -[4], spread-spectrum clocks are used to convert such tones into noise-like signals. However, this increases the noise floor and does not address the underlying problem. This paper shows that chopper-induced IMD is mainly due to amplifier delay, which results in large chopping spikes. A novel fill-in technique is proposed that mitigates these spikes, and so reduces the chopper-induced IMD. In a prototype chopper-stabilized amplifier, it reduces the chopper-induced IMD by 28dB, resulting in an IMD of -126dB for input frequencies near 4FCH (=80kHz). Similarly, it improves the chopped amplifier's two-tone IMD (79 and 80kHz) from -97dB to -107dB, thus maintaining the same IMD as the un-chopped amplifier.
Original language | English |
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Title of host publication | 2021 IEEE International Solid-State Circuits Conference, ISSCC 2021 - Digest of Technical Papers |
Publisher | IEEE |
Pages | 438-440 |
Number of pages | 3 |
ISBN (Electronic) | 9781728195490 |
DOIs | |
Publication status | Published - 2021 |
Event | 2021 IEEE International Solid-State Circuits Conference, ISSCC 2021 - San Francisco, United States Duration: 13 Feb 2021 → 22 Feb 2021 |
Publication series
Name | Digest of Technical Papers - IEEE International Solid-State Circuits Conference |
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Volume | 64 |
ISSN (Print) | 0193-6530 |
Conference
Conference | 2021 IEEE International Solid-State Circuits Conference, ISSCC 2021 |
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Country/Territory | United States |
City | San Francisco |
Period | 13/02/21 → 22/02/21 |
Bibliographical note
Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-careOtherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.