Patent ID: 7786792

Claim:
A circuit for generating a reference voltage, the circuit comprising: an amplifier comprising an inverting input, a non-inverting input and a current output; an integrator configured to integrate a charge from an input and to produce an output having a voltage proportional to the integrated charge; a voltage buffer configured to produce one or more outputs in response to the integrated voltage; a diode junction voltage generator configured to produce a first diode junction voltage in response to a first bias current density, and to produce a second diode junction voltage in response to a second bias current density, wherein the first bias current density is higher than the second bias current density; a first composite voltage generator configured to generate a first composite voltage comprising at least a fraction of the first and/or second diode junction voltage; a first capacitor having first terminal and a second terminal, the second terminal coupled to the amplifier inverting input; and a plurality of switches configured to alternate between a first mode of operation and a second mode of operation, wherein: one or more of the plurality of switches are configured to, in the first mode of operation, couple the amplifier output terminal to the amplifier inverting input terminal, couple the second diode junction voltage to the amplifier non-inverting input terminal, and couple the first composite voltage to the first terminal of the first capacitor; and, one or more of the plurality of switches are configured to, in the second mode of operation, couple the first diode junction voltage to the amplifier non-inverting input, couple the amplifier output to the integrator input, and couple a first one of the voltage buffer outputs to the first terminal of the first capacitor.