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Fast Response Differentiator

IP.com Disclosure Number: IPCOM000048951D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Olsen, FW: AUTHOR

Abstract

Faster, more accurate differentiation of a voltage signal is accomplished by expanding the ramp of the signal simultaneously with both an inverting and non-inverting amplifier and differentiating the combined, expanded signals.

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Fast Response Differentiator

Faster, more accurate differentiation of a voltage signal is accomplished by expanding the ramp of the signal simultaneously with both an inverting and non- inverting amplifier and differentiating the combined, expanded signals.

Referring to the figure, an input signal at terminal 1 is applied to the inverting input of a high voltage operational amplifier 2 and the non-inverting input of operational amplifier 3. The outputs of these amplifiers result in signals with opposite slopes, as shown. These signals are respectively applied to the inputs of s differentiation operational amplifier 4 where the combined slopes provide a steeper effective ramp. The rate of voltage change then becomes sufficient to enable differentiation with a circuit having faster R-C components of capacitor 5 and resistors 6 and 7.

The feedback path from the output of amplifier 4 to its inverting input is through the wiper of potentiometer 8 and resistors 7 and 6. Resistor 6 and resistor 9, connected to the non-inverting input of amplifier 4, provide a voltage divider that together with resistor 7 further provide a low resistance equivalent to that which would otherwise be required for a stable, fast response with little noise. This arrangement reduces the ordinarily required impedance to approximately one hundredth.

The output of operational amplifier 4 is connected to the non-inverting input of operational amplifier 10, having a gain of unity to provide an outp...