This paper describes a TTL-to-CMOS input buffer that has no static power consumption for the typical TTL voltage level. The input buffer utilizes a feedback configuration to eliminate static power consumption that renders hysteresis characteristic. The hysteresis characteristic is equivalent to that of a Schmitt trigger and thus provides good noise immunity. A prototype circuit was implemented in a 0.8 µm CMOS process, and the through current is measured to be only 8.9 µA and 11.7 µA. for the input of 0.8 V and 2.2 V (the worst case TTL level), respectively. The input buffer gives full-swing output upto 170 MHz when driving a minimum sized inverter with the worst case TTL level according to SPICE simulation .