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Programmable Integrator Circuit With Variable Integration Reference

IP.com Disclosure Number: IPCOM000034276D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 28K

Publishing Venue

IBM

Related People

Anderson, PM: AUTHOR [+2]

Abstract

The integrator circuit uses a multiplying digital-to-analog converter to digitally program the integration gain. A pair of differential amplifiers is used to re-reference signals and allow integration with respect to voltages other than ground. The circuit is shown in the figure and includes Diff Amp 1 which finds the difference between Vin and Vref (the new integration reference), and re-references that difference to GND. Normal integration takes place, then with R1, C1, and the Op Amp 8. The non-inverting Multiplying D->A converter 10, when programmed for zero output voltage, does not contribute to the integration time constant, but when it is programmed for output other than zero, it contributes current to the integration process. The greater the programmed multiplication factor, the greater the integrator's gain.

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Programmable Integrator Circuit With Variable Integration Reference

The integrator circuit uses a multiplying digital-to-analog converter to digitally program the integration gain. A pair of differential amplifiers is used to re- reference signals and allow integration with respect to voltages other than ground. The circuit is shown in the figure and includes Diff Amp 1 which finds the difference between Vin and Vref (the new integration reference), and re- references that difference to GND. Normal integration takes place, then with R1, C1, and the Op Amp 8. The non-inverting Multiplying D->A converter 10, when programmed for zero output voltage, does not contribute to the integration time constant, but when it is programmed for output other than zero, it contributes current to the integration process. The greater the programmed multiplication factor, the greater the integrator's gain. R2 sets the amount of the overall contribution from converter 10. Since the integrator circuit is inverting, an inverter stage 12 must follow it. Then comes Diff Amp 2, which re-references its + input with respect to Vref, and the process is complete.

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