Abstract
This paper proposes an advanced test circuit for detecting the connectivity between a drum ring of laser printer and PCB. The detection circuit of charge sharing is proposed, which minimizes the influences of internal parasitic capacitances. The test circuit is composed of precharge circuit, analog comparator, level shifter. Its functional operation is verified using $0.6{\mu}m$ 3.3V/40V CMOS process parameter by HSPICE. Access time is100ns. Layout of the drum contact test circuit is $465{\mu}m\;{\times}\;117{\mu}m$.