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Bipolar to Binary Converter

IP.com Disclosure Number: IPCOM000081852D
Original Publication Date: 1974-Aug-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Cama, CJ: AUTHOR

Abstract

Given a voltage signal that travels positive and negative with respect to some quiescent level, this circuit provides an output which switches between on-off stable levels, such as +V and ground, as the input signal exceeds predetermined positive and negative threshold levels +V(th) and -V(th).

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Bipolar to Binary Converter

Given a voltage signal that travels positive and negative with respect to some quiescent level, this circuit provides an output which switches between on- off stable levels, such as +V and ground, as the input signal exceeds predetermined positive and negative threshold levels +V(th) and -V(th).

In Fig. 1, bipolar input signal A has positive and negative-going spikes 10, 12. It is the objective that the output, curve B, switch between off and on levels 14, 16 whenever there is a reversal of the polarity of the input signals A. For this purpose, the circuit provides a threshold signal C which is derived from output B for comparison with input A.

Fig. 2 shows a circuit in which transistor Q3 is utilized in a common emitter fashion to provide the above-described function in a manner which is device insensitive. Input A is applied with feedback threshold signal C to operational amplifier 10, the output of which (on line 12) switches Q3 between saturation and cutoff. Hence, the voltage at the collector of Q3 (output B) switches between a positive level determined by the network R5, R6, R7 and R8 when Q3 is off to a level slightly above ground when Q3 is in saturation.

From this output voltage, threshold level C is provided by voltage division through R6, R7 and R8 to be a chosen level anywhere between V(satQ3) and -V supply. Returning to Fig. 1, the crossovers of this feedback voltage C and signal A switch operational (i.e., differential) a...