Leeds & Northrup Company

General Signal Corporation

James J Hitt

Scott L Kern

George C Mergner

George W Deffendall

The square root insertion circuit of this invention has an operational amplifier circuit with a multiplying circuit of the voltage-time product type in its negative feedback path. The multiplying circuit is connected so that the time factor is proportional to the amplifier output signal and the voltage factor is also proportional to the amplifier output signal. Thus, the multiplying circuit acts as a squaring circuit to cause the output signal of the amplifier to be directly related to the square root of its input signal.

Square root circuit with voltage-time multiplier

A square root circuit is provided with a high gain amplifier for receiving the input and a squaring circuit in the negative feedback circuit of the amplifier to produce the desired square root output. A second negative feedback path is provided with a feedback resistor and switching means for selectively completing the connection of the second feedback path when the amplifier input falls below a certain predetermined level so that the amplifier provides a linear response in the low input region. This linear response will make the accurate setting of the zero possible without any manual switching in the amplifier feedback.

Square root circuit with stable linear cut-off

A preamplifier for use primarily with a solid state line scanner for amplifying the signal output from the scanner and suppressing the noise from switching spikes featuring a cascode-connected input stage in a preamplifier having its gain stabilized by negative feedback.

Preamplifier for low voltage signals in the presence of high voltage

An analog to digital converter of the ramp-integrator type with provisions to reduce errors due to offset voltages. The cycle which is utilized includes a preconditioning cycle during which the capacitor is charged while the input to the buffer amplifier is connected to the datum level voltage, such as ground. A microprocessor is used to compute the unknown signal.

Analog to digital converter with offset error correction

The displacement of the diaphragm in a differential pressure sensor of the differential capacitor type produces an output signal substantially linearly related to the displacement. The capacitors are charged in parallel from a constant current source for a fixed period of time and discharged through separate discharge circuits for another fixed period of time. An integrating differential amplifier connected to the two capacitors as they discharge produces an output signal related to the area between the two discharge curves which is substantially linearly related to the extent of displacement of the diaphragm of the differential pressure sensor. The output from the amplifier is used to control the current output from the device.

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Willow Grove, PA, United States of America

James J Hitt