1. Pass Transistor Logic EMT 251

2. Pass Transistor Logic I n p u t s Switch Network Out A B B B

3. Pass Transistor Logic Gate is static – a low-impedance path exists to both supply rails under all circumstances NMOS transistors only No static power consumption Ratioless (W/L) Bidirectional (versus undirectional)

4. Complementary Pass Transistor Logic (CPL) Dual-rail form of pass transistor logic Avoids need for ratioed feedback Optional cross-coupling for rail-to-rail swing

5. Example: AND/NAND gate

6. Example: OR/NOR gate

7. Example : XOR/XNOR gate

8. Cascaded Technique Wrong!! Correct!!

9. Draw a CMOS circuit based on this logic equation. Use a minimum number of transistors.

10. Transmission Gate Logic EMT 251

11. Transmission Gate Logic (TG) Most widely used solution Use both NMOS and PMOS in parallel Can be used for logic circuit implementation Full swing bidirectional switch controlled by the gate signal (strong ‘0’ and ‘1’) P N A(V in ) B (V out ) s s A (V in ) B (V out ) s s

12. The MOS transistor pass gate 1 1 0 passes a good 0 1 0 0 0 1 passes a bad 1 passes a bad 0 passes a good 1 nMOS pMOS Near Short CCT Resistance small

13. TG as a Tristate Buffer B=A ( or Z when S=0 ) s A A(V in ) S Tn Tp B (V out ) 0 0 off off Z (high impedance state (blocks logic flow)) 0 1 on off 0 (nMOS passes strong 0, pMOS off when V out <V thp ) 1 0 off off Z (high impedance state (blocks logic flow)) 1 1 off on 1 (pMOS passes strong 1, nMOS off when V out >V dd -V thn ) In steady state

14. Example : OR gate

15. Example : AND gate

16. Example : XOR gate