Low power reference current generator with tunable temperature sensitivity

摘要

An improved reference current generator is provided. A voltage difference generator generates two voltages that are separated by a relatively small electrical potential. The two closely separated voltages are applied across a resistive element with relatively large impedance value resulting in a small and stable reference current. The result is a power efficient, temperature compensated reference current generator.

主权项

1. A circuit for generating a reference current, said circuit comprising:
a voltage difference generator configured to receive an input voltage and operable to supply a first voltage and a second voltage with a difference between them and derived from the input voltage, where the first voltage and the second voltage have predefined values that are substantially insensitive to changes in the input voltage, said voltage difference generator comprising: a reference voltage generator adapted to supply a first supply voltage; a voltage buffer amplifier electrically coupled to said first supply voltage and adapted to provide a second supply voltage; and a voltage ladder electrically coupled to said second supply voltage and adapted to supply said first voltage and said second voltage; a first buffer electrically coupled to said first voltage, said first buffer being adapted to supply a third voltage, said first buffer comprising: a first amplifier adapted to: receive said first voltage; receive said third voltage; and compare said first voltage to said third voltage, and, in response, to output a first control voltage; and a first transistor device adapted to receive said first control voltage, and, in response, to supply said third voltage; a second buffer electrically coupled to said second voltage, said second buffer being adapted to supply a fourth voltage, said second buffer comprising: a second amplifier adapted to: receive said second voltage; receive said fourth voltage; and compare said second voltage to said fourth voltage, and, in response, to output a second control voltage; and a second transistor device adapted to receive said second control voltage, and, in response, to supply said fourth voltage; and a resistive element having a substantially linear operating behavior and electrically coupled between said third voltage and said fourth voltage, said resistive element being adapted to generate a reference current that is a function of said third voltage and said fourth voltage; and a current mirror electrically connected in series with the resistive element, said current mirror being adapted to mirror the reference current, wherein the first buffer, the second buffer and the current mirror are comprised of transistors operating solely in a sub-threshold region.