Robust multiple-valued current-mode circuit components based on adaptive reference-voltage control

Power-supply/temperature-variation-aware circuit components, such as a current source and a comparator, based on adaptive reference-voltage control are proposed for robust multiple-valued current-mode (MVCM) circuits. Since the reference-voltage level generated by the proposed reference-voltage generator is changed in proportion to the power supply, the gate-source voltage (V _GS) of PMOS transistor at the current source becomes almost constant against the power-supply variation, which results in realization of the power-supply-tolerant current source. The use of programming the gate size at the proposed reference-voltage generator makes the logical threshold voltage at the comparator changed in accordance with the input-voltage variation due to the power-supply/temperature variation, which results in correctly recognition of the multi-level current signal. As a design example of the MVCM circuits, a sevenlevel current-signal detector including the current source is demonstrated under a 90nm CMOS technology. As a result, the proposed circuit is correctly operated in the operation range 1.0V to 1.4V of the power supply under 25° C ± 50° C variation of the temperature.