Coupling tolerant precision current reference with high PSRR

摘要

Embodiments of the present invention are related to circuits and methods for generating a reference current (Idc). In an embodiment, a voltage-to-current converter circuit is used to generate the reference current (Idc) in dependence on a reference voltage (Vref) and a precision resistor (R0), wherein Idc=Vref/R0. A capacitor (C0) is used to shunt noise that couples into the voltage-to-current converter. A frequency dependent feedback network is used to compensate for instabilities introduced by the capacitor (C0). The capacitor (C0) can be used to shunt noise that couples into the voltage-to-current converter by connecting the capacitor (C0) in parallel with the precision resistor (R0). The frequency dependent feedback network can be used to compensate for instabilities introduced by the capacitor (C0) by connecting the frequency dependent feedback network between a feedback terminal of an amplifier of the voltage-to-current converter circuit and a terminal of the capacitor (C0).

主权项

1. A voltage-to-current converter circuit configured to accept a reference voltage (Vref) and produce a precision reference current (Idc) for a load (Z_Load), the voltage-to-current circuit comprising:
an amplifier (AMP) including a non-inverting (+) input, an inverting (−) input and an output; a transistor (M1) including a control terminal (gate or base), a first current path terminal (source or emitter) and a second current path terminal (drain or collector), with a current path between the first and second current path terminals, wherein the control terminal (gate or base) of the transistor (M1) is driven by the output of the amplifier (AMP); a first capacitor (C1) connected between the inverting (−) input of the amplifier and the first current path terminal (source or emitter) of the transistor (M1); a first resistor (R1) including a first terminal and a second terminal, wherein the first terminal of the first resistor (R1) is connected to the inverting (−) input of the amplifier (AMP); and a second resistor (R2) including a first terminal and a second terminal, wherein the first terminal of the second resistor (R2) is connected to the first current path terminal (source or emitter) of the transistor (M1), and the second terminal of the second resistor (R2) is connected to the second terminal of the first resistor (R1); wherein the precision reference current (Idc) is produced at the second current path terminal (drain or collector) of the transistor (M1).