Verification of stable circuit operation of 180nm current controlled MOS current mode logic under threshold voltage fluctuation

We have succeeded in fabricating 180 nm Current Controlled MOS Current Mode Logic (CC-MCML) and verified the stable circuit operation of 180 nm CC-MCML under threshold voltage fluctuations by measurement. The performance stability of the CC-MCML inverter under the fluctuations of threshold voltage of NMOS and PMOS is evaluated from the viewpoint of diminishing the bias offset voltage ΔVB. The ΔVB, that is defined as (base voltage of output waveform) - (base voltage of input waveform), is a key design parameter for differential circuit. It is shown that when the threshold voltage of NMOS fluctuates in the range of 0.53V to 0.69V, and threshold voltage of PMOS fluctuates in the range of -0.47V to -0.67V, the CC-MCML technique is able to suppress ΔVB within only 30mV, where as the conventionalMCML technique caused maximum ΔVB of 1.0V. In this paper, it is verified for the first time that the fabricated CCMCML is more tolerant against the fluctuations of threshold voltages than the conventional MCML.