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Browse Prior Art Database

Receiver for General Purpose Interface

IP.com Disclosure Number: IPCOM000052704D
Original Publication Date: 1981-Jul-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Brunin, A: AUTHOR

Abstract

The above receiver, which is responsive to low-amplitude input signals, presents good noise immunity, thereby allowing good restitution of the input pulse width.

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Receiver for General Purpose Interface

The above receiver, which is responsive to low-amplitude input signals, presents good noise immunity, thereby allowing good restitution of the input pulse width.

The first stage, comprising transistor T1, diode D1 and resistors R1 to R4, determines the threshold voltage of the receiver.

This voltage is equal to V(T) + V(BE(TI)), V(T) being the emitter voltage of transistor T1 and V(BE(T1)) the base-to-emitter voltage of transistor T1.

The second stage, comprising transistors T2 and T3, is a Schmitt trigger. For one state, transistor T3 is 0N and transistor T2 is OFF. The voltage V(E) on the common emitters of transistors T2 and T3, at the commuting point, is determined by R5, R6 and R7. For the other state, transistor T2 is ON and transistor T3 is 0FF so that V(E) is determined by R5 and R7. Since V(E) depends on the state of the circuit, the driving voltage on the base of transistor T2 has two different values and the corresponding value of the current flowing through resistor R2 has therefore two different values. As voltage V(T) is a function of the current flowing through R2, the threshold at the input of the receiver depends on the state of the second stage.

The third stage, comprising transistor T4, adapts the circuit to TTL (transistor- transistor logic) levels and gives the required power.

Diode D1 prevents a low level at the output of transistor T1 from becoming a high level when the signal at the input of the recei...