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Ultrahigh Resistance Current Source and Differential Cascode Amplifier Application

IP.com Disclosure Number: IPCOM000080354D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Hellwarth, GA: AUTHOR [+2]

Abstract

Semiconductor devices are coupled for providing extremely high output resistance current source circuit arrangements, in a manner particularly well suited for integrated circuits. A high-impedance current drive circuit for the basic current source provides extremely high, stable output impedances. The circuitry is shown driving a state-of-the-art differential cascode amplifier.

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Ultrahigh Resistance Current Source and Differential Cascode Amplifier Application

Semiconductor devices are coupled for providing extremely high output resistance current source circuit arrangements, in a manner particularly well suited for integrated circuits. A high-impedance current drive circuit for the basic current source provides extremely high, stable output impedances. The circuitry is shown driving a state-of-the-art differential cascode amplifier.

The cascode amplifier input voltages introduced at 11 and 12 are amplified to produce a differential voltage output at output terminals 13 and 14. For cascode amplifier 10 to provide high power, stable amplification, it is driven by high output resistance current sources shown generally at 15 and 16. The output resistance of each of the current sources 15 and 16 approaches the product of the square of the common-emitter current gain of the devices used and the dynamic collector- emitter resistance of the transistors. This results in a substantial improvement in the magnitude of current source output resistance, as compared to prior current sources.

The current source 15 employs transistors 17 and 18 coupled as shown, while current source 16 is formed by complementary connections of transistors 19 and 20. Current source 15 is biased by transistors 21 and 22 while source 16 is biased by transistors 23 and 24. Transistor 21 is further driven by transistor 25, while transistor 24 is further driven by transistors...