Stable voltage reference circuits with compensation for non-negligible input current and methods thereof

摘要

A voltage reference circuit includes three or more current mirrors, an operational amplifier, a voltage buffer, two or more diodes, and one or more resistors. The operational amplifier has two inputs separately coupled to an output of two of the three or more current mirrors and an output coupled to the three current mirrors. The voltage buffer has an input coupled to an output of the other one of the three or more current mirrors and another input coupled to an output of the voltage buffer. Each of the diodes is coupled between the output of the two of the three or more current mirrors and one of ground and a negative supply. The one or more resistors are coupled to an output of one or more of the three or more current mirrors to tune effects of input current and establish a first set absolute voltage and temperature coefficient on a voltage reference.

主权项

1. A voltage reference circuit comprising:
a bandgap circuit comprising,
a closed-loop differential operational amplifier, including a non-inverting input port, an inverting input port and an amplifier output port, the non-inverting input port potential being substantially equal to the inverting input port potential, the differential operational amplifier subject to field emission currents;a first circuit comprising a first current mirror including a first gate coupled to the amplifier output port, the first gate having an oxide layer sized to be subject to field emission currents, a first input port coupled to a voltage supply and a first output port coupled to the inverting input port, the first circuit also including a first diode structure coupled between the first output port and a ground potential, anda second circuit comprising a second current mirror including a second gate coupled to the amplifier output port, the second gate having an oxide layer sized to be subject to field emission currents, a second input port coupled to the voltage supply, and a second output port coupled to the non-inverting input port, the second circuit also including a first resistor and a second diode structure coupled in series between the second output port and the ground potential such that the first resistor establishes a proportional-to-absolute temperature (PTAT) current characterized by a selected temperature coefficient; a tuning network coupled to the to the non-inverting input port and the to the inverting input port, the tuning network being configured to provide a complementary-to-absolute temperature (CTAT) current that substantially cancels the selected temperature coefficient; a third circuit comprising a third current mirror including a third gate coupled to the amplifier output port, the third gate having an oxide layer sized to be subject to field emission currents, the third circuit including a third input port coupled to the voltage supply, the third circuit also including a third output port coupled to the tuning network and a second resistor disposed between the third output port and the ground potential, the second resistor coupled to a voltage reference port that is biased such that the CTAT current and the PTAT current are combined to establish a substantially temperature independent voltage reference signal across the second resistor; and a closed-loop buffer amplifier including at least one buffer input coupled to the third output port and at least one buffer output port, wherein the differential operational amplifier includes at least one operational amplifier input transistor and the input port of the buffer amplifier includes at least one buffer input transistor, the size of the at least one operational amplifier input transistor being substantially matched to the size of the at least one buffer input transistor to substantially reduce the field emission currents propagating in the substantially temperature independent voltage reference signal.