a circuit and a method for biasing a compound cascode current mirror that enables high - voltage swing at the output and accurate current mirroring is presented . the cccm has mirror transistors and cascode transistors which may be of a different technology kind . the drain - source voltage vds of the mirror transistor on the input leg of the cccm is held at a voltage vov that is generated by the biasing circuit ; vov is the overdrive voltage of the input mirror transistor of the cccm and the value of vov is maintained by the bias circuit and a feed - back amplifier such that the mirror transistor remains on the edge of its active region , over manufacture deviations and tracks even over operational conditions such as temperature and supply variations . the feed - back amplifier drives the gates of the cascode transistors and uses its feedback node to hold the vds at vov .