초록 ▼

A current source for generating a current that is relatively stable over variations in the power supply voltage and temperature, and over variations in process parameters is disclosed. The current source includes a bias circuit, for producing a compensating bias voltage, and a current mirror. The bi

A current source for generating a current that is relatively stable over variations in the power supply voltage and temperature, and over variations in process parameters is disclosed. The current source includes a bias circuit, for producing a compensating bias voltage, and a current mirror. The bias circuit utilizes a voltage divider to generate a divided voltage based on the power supply value. The divided voltage is applied to the gate of a modulating transistor (biased in saturation) in a first current mirror, which controls a current applied to a linear load device. The voltage across the load device determines the bias voltage, which is in turn applied to the gate of a transistor in the reference leg of a second current mirror. The bias voltage controls the current in the reference leg of the second current mirror, and an output leg mirrors the second reference current to produce a stable output current.

대표청구항 ▼

[ I claim:] [1.] A current source, comprising:a resistor divider coupled between a supply voltage and a reference voltage for producing a divided voltage;a first current mirror connected to said resistor divider and to the supply voltage, said first current mirror comprising a reference leg and an o

[ I claim:] [1.] A current source, comprising:a resistor divider coupled between a supply voltage and a reference voltage for producing a divided voltage;a first current mirror connected to said resistor divider and to the supply voltage, said first current mirror comprising a reference leg and an output leg, said reference leg comprising a first modulating field-effect transistor controlled by the divided voltage for generating a first reference current conducted by the reference leg and a first reference field-effect transistor connected to said first modulating field-effect transistor for maintaining said first modulating field-effect transistor in saturation, said first modulating field-effect transistor having a relatively small channel length which is near the process minimum so that the first reference current varies based upon process variation, and wherein the output leg comprises:a mirror transistor for conducting a first mirrored current corresponding to the first reference current; anda load, for conducting the first mirrored current and for producing a varying bias voltage, which varies with supply voltage and with process variation, responsive to the first mirrored current; anda second current mirror connected to the supply voltage and comprising a reference leg and an output leg, said reference leg comprising a second modulating field-effect transistor connected to the supply voltage and having a gate connected to receive the varying bias voltage which varies with supply voltage and with process variation so that said output leg produces an output current mirroring the second reference current and with the output current having reduced variation despite variation of the supply voltage and process variation.