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Three Level Circuit -- Current Switch Configuration

IP.com Disclosure Number: IPCOM000097452D
Original Publication Date: 1962-Dec-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Palmieri, JA: AUTHOR

Abstract

This circuit provides three-level inverting operation and has inhibit features.

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Three Level Circuit -- Current Switch Configuration

This circuit provides three-level inverting operation and has inhibit features.

The circuit comprises transistors T1 and T2 arranged in a conventional current switch configuration. Voltage source -E and resistor R form the current source for the switch. T1 is connected at its collector electrode to a load circuit including resistor R1 and voltage source E1. T2 is connected at its collector electrode to a load circuit including resistor R2 and voltage source E2. An additional current path, including diode D1 and transistor T3, is connected to the current source. T3 is a common base amplifier having its base electrode connected to a source of variable reference potential E4. The emitter electrode of T3 is connected to a current source including resistor R3 and a voltage source -E3. An input signal is applied to the base T1. An output circuit signal is taken at the collector of T1. Another output circuit is connected to the collector of T2.

A voltage current characteristic taken at the output of the current source is shown in the lower drawing. Curve 22 is the characteristic of the resistor in the current supply. Curve 24 is the emitter-base characteristic of T1. Curve 26 is the emitter-base characteristic of T2. Curve 28 is the combined curve for D1 and T3. A composite characteristic for resistor R, the emitter-base characteristic of T2 and the combined curve for D1 and T3 is indicated by curve 30. The intersections between the composite curve 30 and the curve 24 establish the operating points for the circuit.

A first voltage applied to T1 at time t1 re...