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Automating Bias Circuit

IP.com Disclosure Number: IPCOM000081956D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Davis, DE: AUTHOR [+4]

Abstract

This is an automatic bias circuit for removing the DC component of a signal, while permitting the AC portion of the signal to be converted into useful digital information.

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Automating Bias Circuit

This is an automatic bias circuit for removing the DC component of a signal, while permitting the AC portion of the signal to be converted into useful digital information.

Referring to the drawing, a reset pulse initially closes switch 2 discharging capacitor C1. At the end of the reset pulse interval, two pulses of unequal amplitude representing DC background components of signals are simultaneously applied at terminals A and B. Also, a set pulse closes the integrator input switch 1.

The signals at terminals A and B pass through resistors R1 and R2 and are applied to the inputs of difference amplifier 10. The difference between the two levels is provided as the output of difference amplifier 10 at terminal D. This same signal is provided as an input to inverting amplifier 20 providing an inverted output at terminal F. This inverted signal is passed through the integrating amplifier represented by amplifier 30, together with integrating capacitor C1 and integrating resistor R3.

The integrated output provided at node C is fed back through R4 to one of the inputs of difference amplifier 10. As a result of the feedback, the potential at this latter input of difference amplifier 10 is either increased or decreased to a level equal to the potential at the second input to the difference amplifier. When this occurs, the value of voltage difference at the difference amplifier output at terminal D goes to zero.

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