Nama : I Made Wiratha Nungrat

NIM : 13209057

Homework 3

CMOS Inverter design for comparison between NAND and NOR CMOS gate

Inverter Gate design

Figure 1. The schematic diagram of the CMOS inverter with one nMOS at the bottom and one pMOS at the top.

Gate Design

Figure 1. Layout design of Inverter

Logic Simulation

Figure 2. Voltage vs Time analysis from Inverter

From design above, we can see the waveform is consistent with truth table, so this design was correct and

that rise and fall time is 4 ps

Truth table of CMOS Inverter

Input Logic

Output Logic

0 1

1 0

Analog Input (V)

Analog Output (V)

0.0 1.2

1.2 0.0

Inverter Delay

Rise time from CMOS Inverter is 4 ps

Fall time from CMOS Inverter is 4 ps

Inverter design above was designed from scratch or not using chip generator because the limitation of

default layout. Manual design with strict restriction to design rule, we get (W/L)p = 15, and (W/L)n = 5.

So inverter design for (Wp/Wl) = 15/5 = 3 we got latency or delay 4 ps.

NAND Gate Design

Figure 3. Gate symbol, Logic gate of NAND and truth table

Gate Design

Figure 4. Layout design of NAND gate

Logic Simulation

Figure 5. Voltage vs Time analysis from NAND gate

From design above, we can see the waveform is consistent with truth table, so this design was correct and

From design above, we can see that rise and fall time is 4 ps

Truth table of NAND Gate

A B Out

0 0 1

0 1 1

1 0 1

1 1 0

NAND gate Delay

Rise time from NAND gate is 4 ps

Fall time from NAND gate is 4 ps

NAND gate design above was designed from scratch because the goal is to match the delay with inverter.

Manual design with strict restriction to design rule, we get (W/L)p = 6, and (W/L)n = 3. So NAND gate

design for (Wp/Wl) = 6/3 = 2 we got latency or delay 4 ps. This result may not be following the nature of

electron mobility and hole mobility, which is PMOS gate must be at least 3 times of NMOS width. This is

because PMOS gate is arranged with parallel position and NMOS in serial fashion.

NOR Gate Design

Figure 6. Gate symbol, Logic gate of NOR and truth table

Gate Design

Figure 7. Layout design of NOR gate

From design above, we can see the waveform is consistent with truth table, so this design was correct and

From design above, we can see that rise and fall time is 6 ps

Truth table of NAND Gate

A B Out

0 0 1

0 1 0

1 0 0

1 1 0

NOR gate Delay

Rise time from NAND gate is 6 ps

Fall time from NAND gate is 6 ps

NOR gate design above was designed from scratch because the goal is to match the delay with inverter.

Manual design with strict restriction to design rule, we get (W/L)p = 17, and (W/L)n = 5. So NOR gate

design for (Wp/Wl) = 17/5 = 3,5 we got latency or delay 6 ps.

Questions

1. Only NAND gate which can match the delay of inverter with 4 ps delay.

(W/L)p = 6

(W/L)n = 3

2. NOR gate have bigger size than NAND gate because the PMOS in NOR gate arranged in serial

fashion