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Amplifier with Isolated Output

IP.com Disclosure Number: IPCOM000091653D
Original Publication Date: 1968-Apr-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Masterson, RJ: AUTHOR

Abstract

The DC input signal is amplified by conventional differential DC amplifier 10 that is powered from a floating power supply. The output of amplifier 10 is applied to a summing point which comprises voltage-controlled capacitor 12. In addition to the input signal, a feedback voltage is summed at this point so that capacitor 12 is varied as a result of the difference between the input signal and the feedback signal. FM oscillator 14 has its frequency varied by the capacity variation of capacitor 12. The oscillator 14 output is amplified and limited in stage 16. The output of stage 16 is transformer-coupled to frequency discriminator circuits 18 and 20. As the input voltage is increased, changing the capacity of capacitor 12 and the frequency of oscillator 14, the output of discriminators 18 and 20 increases.

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Amplifier with Isolated Output

The DC input signal is amplified by conventional differential DC amplifier 10 that is powered from a floating power supply. The output of amplifier 10 is applied to a summing point which comprises voltage-controlled capacitor 12. In addition to the input signal, a feedback voltage is summed at this point so that capacitor 12 is varied as a result of the difference between the input signal and the feedback signal. FM oscillator 14 has its frequency varied by the capacity variation of capacitor 12. The oscillator 14 output is amplified and limited in stage 16. The output of stage 16 is transformer-coupled to frequency discriminator circuits 18 and 20. As the input voltage is increased, changing the capacity of capacitor 12 and the frequency of oscillator 14, the output of discriminators 18 and 20 increases. Discriminator 18 develops the feedback signal which is applied to the summing point. The output from discriminator 18 produces a voltage at capacitor 12 tending to reduce the difference voltage across such capacitor 12. Discriminator 20 develops the output signal which can be further amplified through amplifier 22 before being coupled to output terminal
24. Since discriminator 20 is transformer-coupled to limiter 16, this arrangement permits complete isolation of the output section from the floating input section.

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