Ultra high-compliance CMOS current mirrors for low voltage charge pumps and references

We present a study of current mirror topologies for reference sources and PLL charge pumps, where the objective is to achieve excellent input to output DC matching over almost the whole available power supply range, while maintaining a very high output resistance. From the ideal requirements, we contrast existing designs and develop new topologies which come close to the ideal in terms of available range and resistance, by using regulation at the input as well as output. We consider noise, systematic and random and matching penalties in each circuit. It is shown that mirrors operating in the triode region exhibit lower random mismatch compared with the equivalent conventional mirrors. Measured results are presented from a 0.25 μm 2.5 V CMOS test-chip.