Results 251 to 260 of about 3,714 (283)
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The superconducting chopper amplifier-an analysis
Journal of Physics E: Scientific Instruments, 1979An analysis is given of the operation of the amplifier used for the detection of small DC voltages with a resolution of approximately 10-11-10-12 V. It is shown that the development of modulators with large normal resistances is not desirable when aiming for the ultimate insensitivity due to the large Johnson noise which is introduced.
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A gain-stabilised superconducting chopper amplifier
Journal of Physics E: Scientific Instruments, 1979Describes how the gain of a superconducting chopper amplifier can be stabilised by the application of negative feedback. The circuit has the additional advantages of high input impedance and excellent linearity.
R Fletcher, M R Stinson
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Improved sensitivity for the superconducting ’’chopper’’ amplifier
Review of Scientific Instruments, 1976A heterodyning modulation technique is described which results in an improved sensitivity for the superconducting chopper amplifier. Dc sensitivities of 3×10−12 V were obtained in a 1 Hz noise bandwidth. An experimental comparison of various modulation schemes is presented.
C. B. Friedberg, C. H. Galfo
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Low level transistorized chopper amplifier
IRE Transactions on Telemetry and Remote Control, 1957Low-level transistorized chopper amplifiers have been constructed for a specific missile application. With minor modifications, these amplifiers can meet the requirements for general usage. The chopper is capable of processing 900 signals per second at a common mode rejection of 1000:1. The gain is smoothly adjustable ± 20 percent of full scale and the
Harold F. Harris, T. Eugene Smith
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Chopper-stabilized operational transconductance amplifiers
IEEE Transactions on Instrumentation and Measurement, 1993A technique for chopper-stabilizing commercial linearized operational transconductance amplifiers (OTAs) to remove output offset current errors is described. Design equations which illustrate performance tradeoffs as a function of component values are given. The results are verified experimentally using a common bipolar OTA. >
S.E. Nordquist +2 more
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Auto Correction Feedback for Ripple Suppression in a Chopper Amplifier
IEEE Journal of Solid-State Circuits, 2009This paper proposes a local feedback, named Auto Correction Feedback (ACFB), used in a chopper amplifier to suppress its offset related ripple. It nulls out amplifier's offset in DC domain which would otherwise become modulated ripple at the chopper amplifier's output, instead of filtering the ripple by a post filter.
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On the Susceptibility of Chopper Operational Amplifiers to EMI
IEEE Transactions on Electromagnetic Compatibility, 2016This paper focuses on the susceptibility to electromagnetic interference (EMI) of chopper operational amplifiers, which are usually preferred to common ones when low-noise and low-offset features are required. The demodulation of EMI carried out by such devices is investigated analyzing the linear distortion that results from the modulation and the ...
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Measurement and analysis of input current noise in chopper amplifiers
2012 Proceedings of the ESSCIRC (ESSCIRC), 2012This paper explains how the charge injection and clock feed-through of MOSFET switches causes significant input currents and current noise in chopper amplifiers. The current noise can be modeled as a form of shot noise with a white power spectral density (PSD). Both the input current and its noise PSD increase linearly with the chopping frequency. This
Jiawei Xu 0001 +5 more
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Analysis and Design of a Ripple Reduction Chopper Bandpass Amplifier
IEEE Transactions on Circuits and Systems I: Regular Papers, 2018A low-power low-noise chopper amplifier for biosensor applications is proposed. To tackle the inherent ripple artifacts, it employs a simple ripple reduction method using a bandpass amplifier. The chopper amplifier is a linear periodic time-varying system.
Jiawei Zheng +2 more
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Chopper Amplifiers Demystified Slides
2018AbstractIn CMOS amplifiers, component mismatch can easily give rise to offsets of several millivolts. However, this can be reduced to the microvolt level by the application of chopping. Compared to the alternatives, i.e. increasing device area or trimming, the use of chopping has the added advantage of also suppressing 1/f noise and drift.
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