Testing device for differential amplifiers

Claim 2

A testing device for measuring the response time of transistorized differential amplifier upon the application of a transient signal to one of two signal input terminals of said amplifier, comprising in combination: connection means providing access to a first and a second signal input terminal, to a signal output terminal and to a control input terminal of an amplifier to be tested, said connection means further applying suitable voltages of proper polarity to said amplifier; circuit means for coupling said second signal input terminal and said signal output terminal in an inverse feedback loop to effectively cancel the unbalanced voltage between said two signal input terminals in the absence of an input signal; a generator of recurrent signal pulses connected to apply said signal pulses to said first signal input terminal of said amplifier, each pulse having a duration much shorter than its recurrence period; and means for connecting said first signal input terminal and said signal output terminal of the amplifier under test to a visual testing instrument.

Claim 3

The testing device of claim 1, wherein said circuit means comprises a second differential amplifier providing a high gain and having a first input terminal connected to said signal output terminal of the amplifier under test, having a second input terminal receiving a comparison voltage, and having an output terminal connected through a voltage divider to said second signal input terminal of the amplifier under test.

Claim 4

A testing device for measuring the response time of transistorized differential amplifier upon the application of a transient signal to one of two signal input terminals of said amplifier, comprising in combination: connection means providing access to a first and a second signal input terminal, to a signal output terminal and to a control input terminal of an amplifier to be tested, said connection means further applying suitable voltages of proper polarity to said amplifier; circuit means for coupling said second signal input terminal and said signal output terminal in an inverse feedback loop to effectively cancel the unbalanced voltage between said two signal input terminals in the absence of an input signal, wherein said circuit means comprises a second differential amplifier providing a high gain and having a first input terminal connected to said signal output terminal of the amplifier under test, having a second input terminal receiving a comparison voltage, and having an output terminal connected through a voltage divider to said second signal input terminal of the amplifier under test; a generator of recurrent signal pulses connected to apply said signal pulses to said first signal input terminal of said amplifier, each pulse having a duration much shorter than its recurrence period wherein said signal generator comprises a multistable device and a delay unit with reciprocal connections arranged such that said multistable device generates at a plurality of output terminals thereof a sequence of pulses, said sequence having a duration, termed ''''measurement period, '''' which is no greater than 1/25th the duration of a period of recurrence; and means for connecting said first signal input terminal and said signal output terminal of the amplifier under test to a visual testing instrument.

Claim 5

A testing device for measuring the response time of transistorized differential amplifier upon the application of a transient signal to one of two signal input terminals of said amplifier, comprising in combination: connection means providing access to a first and a second signal input terminal, to a signal output terminal and to a control input terminal of an amplifier to be tested, said connection means further applying suitable voltages of proper polarity to said amplifier; circuit means for coupling said second signal input terminal and said signal output terminal in an inverse feedback loop to effectively cancel the unbalanced voltage between said two signal input terminals in the absence of an input signal, wherein said circuit means comprises a second differential amplifier providing a high gain and having a first input terminal connected to said signal output terminal of the amplifier under test, having a second input terminal receiving a comparison voltage, and having an output terminal connected through a voltage divider to said second signal input terminal of the amplifier under test; a generator of recurrent signal pulses connected to apply said signal pulses to said first signal input terminal of said amplifier, each pulse having a duration much shorter than its recurrence period wherein said signal generator comprises a multistable device and a delay unit with reciprocal connections arranged such that said multistable device generates at a plurality of output terminals thereof a sequence of pulses, said sequence having a duration, termed ''''measurement period, '''' which is no greater than 1/25th the duration of a period of recurrence; and means for connecting said first signal input terminal and said signal output terminal of the amplifier under test to a visual testing instrument.

Claim 6

The testing device of claim 3, wherein when a first type-pulse is applied to said first signal input terminal of the amplifier under test from a first output terminal of said multistAble device, said first-type pulse terminating near a mid-point moment of each measurement period, a moment from which the response time can be observed at the output terminal of the amplifier.

Claim 7

The testing device of claim 4, wherein a second type pulse is applied to said second signal input terminal of the amplifier under test from a second output terminal of said multistable device and continues during at least the second half of said measurement period, and wherein a fourth output terminal of said multistable device is connected to apply to said control input terminal an inhibiting pulse during said second half of said measurement period, said inhibiting pulse terminating before the end of said measurement period and inhibiting the operation of the amplifier under test.

Claim 8

A system for testing differential amplifiers, comprising the testing device of claim 5 and a dual-beam oscilloscope, wherein said output terminal of the amplifier under test is connected to one of the vertical input terminals of said oscilloscope, a first switch connects said first signal input terminal of said amplifier to the other vertical input terminal of said oscilloscope, and a second switch connects a third output terminal of said multistable device to a synchronization input terminal of said oscilloscope during first measurement of said response time.

Claim 9

The system of claim 6, wherein said first and second switches are placed in a second position which connects the control input terminal of the amplifier under test to both of said other vertical input terminal and said synchronization input terminal of said oscilloscope during a second measurement of response time.

Claim 10

A testing device for measuring the response time of a differential amplifier, wherein said amplifier has a pair of input terminals and an output terminal, comprising in combination: signal generating means connectable to said amplifier for applying recurrent pulses to at least one of said input terminals, time delay measuring means connectable to said one input terminal and to said output terminal for measuring the time between each of said pulses and the consequent pulse delivered by said output terminal, and compensating means for applying a compensating voltage between said pair of input terminals to cancel the unbalanced voltage between said terminal pair in the absence of input signals to said terminal pair.

Claim 11

A testing device for measuring the response time of a differential amplifier, wherein said amplifier has a pair of input terminals and an output terminal, comprising in combination: signal generating means connectable to said amplifier for applying recurrent pulses to at least one of said input terminals, time delay measuring means connectable to said one input terminal and to said output terminal for measuring the time between each of said pulses and the consequent pulse delivered by said output terminal, and compensating means for applying a compensating voltage between said pair of input terminals to cancel the unbalanced voltage between said terminal pair in the absence of input signals to said terminal pair.