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Operational Amplifier With Small Delay

IP.com Disclosure Number: IPCOM000052890D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Hutson, DJ: AUTHOR

Abstract

In certain applications, such as for connecting a probe to a tester, an operational amplifier with a very small delay is needed. The operational amplifier shown above has a gain of 10 and a delay of less than 7.5 nanoseconds.

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Operational Amplifier With Small Delay

In certain applications, such as for connecting a probe to a tester, an operational amplifier with a very small delay is needed.

The operational amplifier shown above has a gain of 10 and a delay of less than 7.5 nanoseconds.

This amplifier consists of a combination of a cascode front end stage with a special output stage.

The circuit consists of a modified cascode differential amplifier (Q1, Q2, Q3) which, together with capacitor C1, contributes the dominant pole of the amplifier. Cascode current switch Q4 and Q5 in combination with the cascode differtial amplifier provides a high DC open loop gain of greater than 2,000. The level shifter (Q6 and Z1) and output stage (Q7 and Q8) comprise the rest of the circuit. The gain of 10 is established by the feedback resistors R1 and R2. DC offset adjustment is made by varying the 15 ma current source, and DC gain adjustment is made by varying R2. All transistors except Q5 are high frequency RF devices.

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