Low Voltage Swing Logic • Large Diffusion Connected Network (DCN) produces differential small signals. • Extremely high-performance;Expensive reset network, reset cycle, huge load on clock.
Current Mode Differential Logic • Utilize current mode logic to get stable low-voltage swing. S0 S1 SA S1’ Xs Rs CDL • Shunt transistors and resistors replace reset network. • Small transistor count, no reset, small dynamic power, small clock load.
Current Mode vs. Voltage Mode • Smaller shunt resistor, faster response. Limited by threshold voltage of sense amplifier. Time Constant Voltage Mode Current Mode
CMDL Design • Basic design rules: • Any differential input pair must be connected through a shunt resistor or a closed transistor. (No full voltage swing in the circuit) • For any differential output pair, only one shunt resistor or closed transistor on the active path.(Differential output signal can be detected) • Applicable to extremely high performance low power datapath designs, such as MUX, barrel shifter and carry-skip adder.
Preliminary Results DELAY AND POWER COMPARISON BETWEEN CMDL AND LVS CIRCUITS