Pass transistors operation and demonstration

Describes NMOS and PMOS pass transistors

1. Pass Transistor Logic --Prof. Nataraj A. Vijapur

2. Pass transistor Logic Can be used to transfer/steer charge from one node of a circuit to another node. Used in designing Regular arrays such as ROMs, PLAs and Multiplexers

3. Advantages They are not “ ratioed ” devices and can be minimum geometry They do not have a path from VDD to GND, and do not dissipate standby Power.

4. Pass Transistor Logic If gate and drain of a Pass transistor are both High, the source will rise to the lower of the two potentials V DD and V GS -V TH

5. Rules of Pass Transistor Logic One must never drive a Pass transistor with the output of another Pass Transistor. Care should be taken to ensure the existence of Both Charging and Discharging Paths to the inputs of all the inverters. Avoid Sneak paths One must always provide both charging & Discharging Paths to the inverter.

6. Complimentary Pass transistor Logic