Texas Instruments Corporation

John D Morgan

William H Giolma

Richard Edward Boucher

A dropping resistor and a pair of differential current steering pairs coupled to the resistor with each operable to draw and cease drawing current through the resistor in response to associated corresponding input signals. An integrator is coupled through an emitter follower to one end of the resistor for integrating the current due to the difference in voltage from that voltage established when only one of the pair draws current through the resistor. Preferably the resistor is integrated on a semiconductor chip together with the remainder of the charge pump and integrator circuitry.

High frequency charge pump/integrator circuit

A current to frequency converter having an operational amplifier with two inputs, an output, and a feedback capacitor connected between one input and the output to produce an output voltage waveform having a rate of change proportional to the input current between a first and second predetermined voltages. A level detector and active switching devices to detect the second predetermined voltage level and reset the voltage level of the waveform to the first predetermined voltage level. The level detector produces an output signal when the second voltage level is reached. The output signals form a digital pulse stream having a frequency proportional to the input current.

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John D Morgan