A 3.3-V/5-V low power TTL-to-CMOS input buffer

A separately self-biased transistor-transistor logic (TTL)-to-CMOS input buffer (SSIB) is proposed. Its logic threshold voltage is kept at 1.4 V when supply voltage is changed from 3.3 V to 5 V, making it suitable for 3.3-V/5-V dual voltage applications. It has low power dissipation, high operating speed, and a logic threshold voltage less sensitive to process and supply voltage variations. The proposed SSIB input buffer was realized in a 0.8-/spl mu/m single-polysilicon double-metal (SPDM) CMOS technology, The measured logic threshold voltage variations due to process variations are /spl plusmn/24 mV for 5 V supply and /spl plusmn/16 mV for 3.3 V supply, respectively. Its logic threshold voltage variations due to supply voltage variation from 3.3 V to 5 V are within 10 mV. In ring oscillator configuration, the measured delay and power dissipation are 0.45 ns and 0.37 mW for 5-V supply and 0.51 ns and 0.14 mW for 3.3-V supply, respectively.