Abstract: Circuit which is suitable to be manufactured in integrated circuit form for providing a constant source current at an output for driving a load. The circuit includes a reference current source for providing a reference current, and a PNP turn around circuit consisting of matched transistor devices. The output current from the circuit is provided at the collector electrode of a second one of the matched transistors. A third transistor is coupled between the second transistor and the output of the circuit in a cascode configuration to buffer the collector of the second transistor from variation in the voltage level appearing at the output of the circuit. Additionally, another transistor is coupled between the reference current source and the cascoded transistor forming therewith a Darlington amplifier which produces a high output impedance at the output of the circuit.

Abstract: A circuit is disclosed which is responsive to an applied alternating input signal for producing an analog output signal the magnitude of which is made proportional to the frequency of the input signal. A triggering circuit is provided which produces a triggering signal on positive transitions of the input signal. A circuit is included for producing a dual ramp output voltage the peak magnitude of which is varied in accordance with the frequency of the applied input signal. A peak detector circuit samples the dual ramp voltage and holds this value until the next cycle of the input signal wherein the dual ramp voltage is again sampled. The triggering circuit also includes a comparison amplifier for providing control signals the state of which are representative of the respective magnitudes of the dual ramp and peak voltages.

Abstract: A unity gain amplifier circuit is disclosed which is responsive to an input signal being applied thereto for sourcing current to an output terminal for driving a load. The unity gain amplifier comprises a differential amplifier having first and second differential inputs at which one input thereof the input signal is applied. A current mirroring circuit is provided for producing balance current drive to the differential amplifier and which is coupled to the output thereof. The output of the differential amplifier provides base drive current to a NPN transistor which is coupled in cascode configuration to a PNP transistor. In response to the input signal being applied to the input of the differential amplifier current is sourced from the collector electrode of the PNP transistor for providing both sourcing current at the output of the unity gain amplifier and for establishing feedback to the second input of the differential amplifier such that unity gain is established.

Abstract: A method and circuit are disclosed for providing input voltage transient signal protection to integrated circuits. The circuit comprises two NPN transistors fabricated integrally with the integrated circuit. The emitter of the first one of the transistors is adapted to be connected to an input of the integrated circuit. The N-epi collector regions of both transistors are connected, as is the emitter of the second transistor, to the P-substrate of the integrated circuit. The bases of the two transistors are connected together.