Stacked analog—I²L LSI

Recently, with the advance of microfabrication techniques, extremely many circuits are integrated in a silicon chip. As a result, the power density is increased and the processing of this power density becomes a key to realize a VLSI. As a means to resolve this problem, this paper discusses a method for reducing the power consumption in the entire analog-digital LSI by resuing in the I²L circuit, the current already used in the analog circuit. Several representative analog circuits are studied in this paper and a stacking of the analog circuit and the I²L circuit is investigated. As an example, when an I²L circuit is combined in the constant current souce side of the differential amplifier with the signal gain of 36 dB, the noise leakage from the I²L circuit to the output of the differential amplifier is about -14 dB (about 2 mV). This stacked analog -I²L is applied to an actual integrated circuit. Without losing the function and characteristics of the original integrated circuit the apparent power consumption of the I²L circcuit is made zero and the power consumption of the entire integrated circuit is reduced from 65 mW to 34 mW, which is about a 50% reduction.