High precision bidirectional chopper amplifier with extended common mode input voltage range

Bortun, Nicusor; Stan, Matei Nicolae; Brezeanu, Gheorghe

doi:10.1109/smicnd.2015.7355237

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…It is possible to obtain very low offset voltages using trimming, but this method does not reduce the flicker noise, hence other techniques (chopping and auto-zeroing) are needed to prevent this problem, they also compensate offset changes gradually as the amplifier parameters change due to again and temperature changes. Chopping is one of the major techniques used for offset elimination [2,[6][7][8][9][18][19][20][21][22][23][24], it is favorable in applications where a continuous-time signal is needed, in contrast to auto-zeroing technique, chopper amplifier (fig. 1.3) does not cause noise-folding.…”

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confidence: 99%

Dynamic Offset Compensated Operational Amplifiers

Assim¹,

Balashov²

2021

Preprint

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The given work is devoted to designing and implementing different dynamic offset cancellation techniques for 50 nm technology CMOS operational amplifiers. The goal is to minimize or get rid of the effects of the offset voltage. Offset voltage exists in all differential amplifiers due to the fact that no pair of transistors can be fabricated with the same size, there is always a slight difference in their dimensions (length or width), this gives rise to an undesirable effect called offset, the value of offset voltage for cheap commercial amplifiers are in the range of 1 to 10 mV, de-spite the fact that this isn’t a significant value, due to the high gain of such amplifiers, this voltage is amplified by tens or hundreds of times, this results in clipping of the output signal and this further limits the amplifier’s maximum allowable input voltage within the given dynamic range, hence its of great importance to take this small voltage into consideration, low-offset amplifiers find applications in mixers, analog to digital converters, instrumentation devices, etc. In this thesis, by using two different techniques for removing offset voltage (chopping and auto-zeroing), five low offset operational amplifiers were designed. The implemented methods reduced the flicker noise by more than 457 times (from 9.4 nV/√Hz to 20 pV/√Hz) at 1 Hz. All the simulations were done using Cadence Virtuoso.

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