1. Static CMOS Circuits

2. Static CMOS Circuits
In Static CMOS circuits with n inputs, 2n transistors are needed.
nMOS block is a dual of the pMOS block.
What ever is in series in nMOS, appears in parallel in pMOS and vice versa.
CMOS gates consume power only during the transition of inputs.

3. Static complementary gate structure
Pull-up and pull-down networks
VDD
pull-up
network
out
inputs
Pull-down
network
VSS 7

4. Pull-up/pull-down network design
Pull-up and pull-down networks are duals.
To design one gate, first design one network, then compute dual to get other network. 13

5. Static CMOS Circuits Static CMOS Logic Structure
Logic Gates – Inverter, NAND and NOR
Complex Structures
AOI/OAI Structures
Stick Diagrams
Layouts

6. Inverter 8

7. NAND Gate Va Vb
Vout 1

8. NOR2 Gate Va Vb
Vout 1

9. Static CMOS Circuits Static CMOS Logic Structure
Logic Gates – Inverter, NAND and NOR
Complex Structures
AOI/OAI Structures
Stick Diagrams
Layouts

10. Complex CMOS Structures

11. Xor gate

12. Static CMOS Circuits Static CMOS Logic Structure
Logic Gates – Inverter, NAND and NOR
Complex Structures
AOI/OAI Structures
Stick Diagrams
Layouts

13. AOI/OAI gates AOI = and/or/invert; OAI = or/and/invert.
Implement larger functions.
Pull-up and pull-down networks are compact: smaller area, higher speed than NAND/NOR network equivalents. 11

14. AOI example
invert or
and 12

15. Problems A C B D Y A B C D

16. Problems Design a CMOS circuit to implement the logic
Y = A'B' + B'C + C'A
Make a 2 input CMOS XOR gate to implement
Y = A  B.
CMOS XOR and XNOR gates are similar. Just one of the input pairs (A and A' are reversed).

17. Static CMOS Circuits Static CMOS Logic Structure
Logic Gates – Inverter, NAND and NOR
Complex Structures
AOI/OAI Structures
Stick Diagrams
Layouts

18. Stick diagrams A stick diagram is a cartoon of a layout.
Does show all components/vias (except possibly tub ties), relative placement.
Does not show exact placement, transistor sizes, wire lengths, wire widths, tub boundaries.

19. Stick Diagram of NOR gate

20. Stores charge on inverter gate capacitance:
Dynamic latch
Stores charge on inverter gate capacitance:

21. Dynamic latch stick diagram
VDD in
out
VSS
phi
phi’

22. Static CMOS Circuits Static CMOS Logic Structure
Logic Gates – Inverter, NAND and NOR
Complex Structures
AOI/OAI Structures
Stick Diagrams
Layouts

23. Layout
VDD D Q’
VSS f f’

24. Layout of NOR Gate

25. Stick Diagram of NAND gate