Compensating current source

Details Compensating current source Compensating current source

1975-12-18

1977-01-18

Heyman, John S.

Electrical transmission or interconnection systems

Nonlinear reactor systems

Parametrons

307235T, 330 22, 330 35, H03K 114, H03F 316, H03F 130, H03F 345

Patent

active

040041646

ABSTRACT:
The disclosed circuit is to provide a current source for use on a semiconductor chip having field effect transistors (FET) deposited therein to compensate for variations in the substrate voltage source. Analog type circuits when alone on a semiconductor chip or combined with digital type logic circuits are normally susceptible to disturbances in the bias voltage applied to the substrate of the chip. The obtaining of a uniform output response from an analog type circuit due to an input voltage change has heretofore required the use of off-chip precision voltage sources. Such expensive precision sources can be eliminated and normally variable (.+-. 15%) supplies can be used by providing an on-chip compensating current source which combines with other circuits to provide stable reference voltage levels on the chip for use by the analog circuits.
The compensating circuit comprises two depletion type field effect transistors (FET) in series between a higher voltage source and the substrate voltage, the FET connected to the higher voltage having its gate connected to the common node between the transistors and being in saturation and the lower voltage one having its gate connected to a ground voltage and being conductive in its linear region. An enhancement type transistor has its gate connected to the common node of the two depletion FETs and its source connected to the negative side of the substrate voltage source. By a proper selection of parameters, this circuit will pass a current varying inversely with changes in the substrate supply voltage to provide a compensated current source for other analog circuits. Representative circuits are shown for a stabilized voltage reference, for a differential amplifier current control and a combined circuit.

REFERENCES:
patent: 3700981 (1972-10-01), Masuhara et al.
patent: 3813595 (1974-05-01), Sheng
patent: 3823332 (1974-07-01), Feryszka et al.
patent: 3832644 (1974-08-01), Nagata et al.
patent: 3875430 (1975-04-01), Prak
patent: 3943380 (1976-03-01), Morgan et al.
patent: 3947778 (1976-03-01), Hsiao et al.
Hoffman, "Constant-Current Source for MOSFET Circuits", IBM Tech. Discl. Bull., vol. 17, No. 8, p. 2391, Jan. 1975.
Atwood, "Field Effect Transistor Circuits", IBM Tech. Discl. Bull., vol. 6, No. 9, pp. 91-93, Feb. 1964.
Freeman et al., "Level Shifting Circuit", IBM Tech. Discl. Bull., vol. 18, No. 5, p. 1450, Oct. 1975.
Baitinger et al., "Constant-Current Source Network", IBM Tech. Discl. Bull., vol. 13, No. 9, p. 2516, Feb. 1971.

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