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Filter Device

IP.com Disclosure Number: IPCOM000095679D
Original Publication Date: 1964-May-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Essinger, P: AUTHOR [+2]

Abstract

The circuit passes high-frequency variations in an applied input signal while blocking low-frequency variations.

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Filter Device

The circuit passes high-frequency variations in an applied input signal while blocking low-frequency variations.

The reference level of the input signal applied to terminal 10 tends to vary with time. Superimposed on this low-frequency variation is a random series of information pulses. It is desired that an output appear on line 12 only when an information pulse is applied to terminal 10. The signal applied to terminal 10 is applied through line 14 to a first variable-gain amplifier 16. The output from amplifier 16 is applied to one input of difference amplifier 18.

The other input to amplifier 18 is the output from a second variable-gain amplifier 20. The gain characteristics of amplifiers 16 and 20 are identical. Output line 12 from amplifier 18 is applied as the output from the circuit and is also applied to low-pass filter 22. The output from filter 22 is applied as the input to amplifier 24. The output from filter 22 combines with the output from amplifier 24 to form the feed-back input to amplifiers 16 and 20.

In operation, amplifiers 16 and 20 are initially operating at the same point and there is no output on output line 12 from amplifier 18. The low-frequency variation applied to input terminal 10 causes a small output from amplifier 18 which is applied through filter 22 and amplifier 24 to the feed-back inputs of amplifiers 16 and 20 to maintain them at the same operating point. The low-frequency variation applied to terminal 10, therefor...