Patent ID: 7701269

Claim:
A circuit for managing voltage swings across field effect transistors in the circuit, comprising: an operational amplifier; a reference precision resistor coupled to an input of the operation amplifier, wherein a reference current is supplied to the reference precision resistor to produce a reference voltage; a first field effect transistor and a second field effect transistor, wherein a gate of the first field effect transistor is tied to a gate of the second field effect transistor, wherein a current is supplied to a drain of the second field effect transistor to produce a drain voltage, wherein the operational amplifier receives the reference voltage and provides a negative feedback to the gate of the second field effect transistor so that the drain voltage of the second field effect transistor is substantially equal to the reference voltage, wherein a drain to source resistance of the second field effect transistor is substantially equal to or is a multiple of a resistance of the reference precision resistor, and wherein a gate voltage of the second field effect transistor is applied to a gate of the first field effect transistor to set a bias point of the first field effect transistor; and a third field effect transistor cascoded to the first field effect transistor, wherein a drain of the first field effect transistor is coupled to the source of the third field effect transistor to extend a voltage range in which respective gate voltages of the first field effect transistor and the third field effect transistor maintain a linear relationship with respective drain to source voltages of the first field effect transistor and the third field effect transistor.