Design A1.25Gbps MUX/DEMUX Chip With Equalizer And Pre-emphasis

In the transmission line, due to the transmission line’s non-ideal quality, such as thelimited bandwidth, crosstalk noise and so, the high-frequency components of the signal willbe attenuated, and the noise will be injected to signal too, resulting in Inter-symbolInterference (ISI) and Jitter etc. when the high-speed signal running in transmission line,which limiting the signal’s transmission distance and transmission rate. Equalizer andpre-emphasis, are an effective and affordable way to solve the problem. Equalizer (EQ) issimilar to a "high-pass filter", working in signal receiver. EQ can compensate the attenuationof the high frequency component of the signal passing through the transmission line, so thateach frequency component of the signal is "balanced" to the same level, recovering thedistortion signal. Pre-emphasis circuit is also similar to a "high-pass filter", but it works inthe sending terminal, and strengthens the high frequency component of the signal tocompensate the attenuation of the transmission line in advance before passing through. Withthe pre-emphasis, the signal can be transisted accurately.This paper proposes an equalizer and a pre-emphasis which are both working incontinuous time. Using the EQ and PE, we design a MUX/DEMUX (multiplexer anddemultiplexer) circuit. This chip is able to send either of two input signals to one outputterminal which is called multiplex, and broadcast one input signal to the two outputterminals which is called demultiplex. Adopting SMIC0.18μm1P6M standard CMOSprocess, the designed circuit is able to handle the digital signal with the transmission rate of1.25Gbps. Furthermore, the equalizer in the chip can compensate the attenuation of20inchand40inch FR-4backplane transmission, and the pre-emphasis circuit has four optionalovershoot levels, as3%,25%,50%and95%. The designed chip`s area is1160μm*1460μm,and the power consumption is about100mA.