A multi-channel video multiplexer with high isolation switch

A video multiplexer with high isolation switch and capability of driving load as low as 75 Ω is presented in this paper. The switch consists of a pair of NMOS and PMOS with the noise-shunt path to improve the isolation performance, presenting low on-resistance. The amplifier operates in closed-loop condition for signal buffering or amplification typically, whose circuit design and layout floorplan are considered carefully, leading to low input offset voltage and wide output swing voltage. The channel off isolation between 8-channel of 75 dB, typical input offset voltage of less than 1 mV and output swing voltage of ±3.6 V with load of 150 Ω are achieved under the power supply of ±5 V. This multiplexer is fabricated with a commercial CMOS process with the featured size of 0.6 μm with the active area of 0.8 mm × 0.8 mm including ESD protection structures and power rings.