An accurate and fast copy current circuit arrangement (250) and method for high current ratio having a first branch for carrying a first current ( I load ) ; a second branch for carrying a second current (2 I fb ) ; and a twisted current mirror arrangement (282, 284, 286, 288) coupled between the first branch and the second branch, wherein the second current (2 I fb ) is a copy representative of the first current ( I load ). The twisted current mirror arrangement (282, 284, 286, 288) includes a first current mirror having a first bipolar transistor (282) and a second bipolar transistor (284) whose bases are coupled together; and a second current mirror having a first MOSFET transistor (286) connected in series with the first bipolar transistor (282) and a second MOSFET transistor (288) connected in series with the second bipolar transistor (284), the first and second MOSFET transistors having their gates coupled together. A start-up current source (299) applies a start-up current to the junction between the first bipolar transistor (282) and the first MOSFET transistor (286) and provides bias during circuit operation.
This avoids a conventional error amplifier, uses no closed voltage loop, and no capacitor to stabilize the voltage loop, and provides a faster response time.
This provides more accurate copy current for high current ratio, better linearity and zero input error voltage.