A multilevel data transmission baseband LSI using SC circuits

Abstract

The baseband circuit for multilevel data transmission system was implemented by LSI using SC circuit technology. The waveform‐shaping filter, the full‐wave rectifier for clock regeneration, the narrowband filter and other circuits were constructed by SC circuits. The size and the power dissipation were reduced by constructing all filters in time‐division multiplex. The chip area and the power dissipation in the SC circuit is proportional to the total capacitance, and the total capacitance is determined by the capacitance ratio and the unit capacitance. From such a viewpoint, the narrowband filter used in the clock regeneration is constructed by multirate, and the capacitance ratio was compressed using the N‐path filter. Capacitance partitioning is applied to high‐Q filters to suppress the capacitance ratio. Then by composing all capacitances as the integer multiples of the same unit capacitance, the desired ratio accuracy was achieved based on the unit capacitance of 0.1 pF. The problem of performance degradation due to integer capacitance ratio was minimized by the discrete approximation. When the N‐path filter is composed by the time‐division multiplex scheme, the performance may be degraded greatly due to the parasitic capacitance among wirings. This effect was analyzed and an improvement from the viewpoint of the layout was proposed. As a result, the multilevel data transmission baseband LSI was realized with the chip size of 4.3 × 4/2 mm2 and the power consumption of 35 mW.