Re: replica baising?
replica biasing is used in analog circuits where you want exact mirroring of bias currents with currents in active circuits eg. VCO design.
Here the acitive part is circuit is replicated in bias circuitry , and same voltages should be maintained to exploit the use of replica bias .
please see this , you may get some idea
J. Maneatis, “Low-jitter and process-independent
DLL and PLL based on self-biased techniques,”
Int’l Solid-State Circuits Conference Digest, pp.