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Two Stage Directly Coupled AC Voltage Amplifier

IP.com Disclosure Number: IPCOM000095779D
Original Publication Date: 1964-Jun-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Berger, H: AUTHOR

Abstract

This arrangement is a two-stage, directly coupled AC voltage amplifier. This has transistors T1 and T2 in a grounded-emitter configuration. A high AC voltage gain is obtained even in the presence of a very high DC voltage negative feedback action.

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Two Stage Directly Coupled AC Voltage Amplifier

This arrangement is a two-stage, directly coupled AC voltage amplifier. This has transistors T1 and T2 in a grounded-emitter configuration. A high AC voltage gain is obtained even in the presence of a very high DC voltage negative feedback action.

The resistor combination R1, R2' and R2" produces the base bias for the first stage. Part of the AC voltage, which undergoes a drop at the emitter resistor R3 of the first stage having a stabilizing function, is superimposed on the input AC voltage. This is through the R2C combination by which the input resistance of the circuit is increased substantially. Resistor R2 is formed by the parallel connection of R2' and R2". The collector of the second stage is connected through resistor R4 to the emitter of the first stage. This connection effects both a DC and an AC voltage feedback.

The DC voltage gain of the circuit is essentially determined by the ratio of R4/R3. The AC voltage gain is determined by the ratio of R4/ R2 in parallel to R3. With R2 selected to be smaller than R3, the DC voltage feedback is substantially higher than the AC voltage feedback.

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