Add MOS transistors to the circuit

Add MOS transistors to the circuit in Fig. 9.69 to create a two-input BiCMOS NAND gate.

The Correct Answer and Explanation is :

iturn0image0turn0image2turn0image3turn0image4A BiCMOS NAND gate combines the high-speed switching capabilities of bipolar junction transistors (BJTs) with the low-power consumption of complementary metal-oxide-semiconductor (CMOS) technology. This integration leverages the strengths of both transistor types to achieve efficient and high-performance logic operations.

Circuit Design:

In a two-input BiCMOS NAND gate, the circuit typically consists of:

1. Pull-Up Network:

• Two PMOS transistors (denoted as PA and PB) are connected in parallel between the output node and the positive supply voltage (VDD).
• These transistors are controlled by the inputs A and B.

1. Pull-Down Network:

• Two NMOS transistors (NA1 and NB1) are connected in series between the output node and ground (GND).
• These transistors are also controlled by the inputs A and B.

1. Bipolar Transistors:

• An NPN transistor (Q1) is connected in series with a resistor between VDD and the output node.
• A PNP transistor (Q2) is connected in series with a resistor between the output node and GND.
• The bases of these transistors are driven by the outputs of the CMOS pull-up and pull-down networks, respectively.

Operation:

The BiCMOS NAND gate operates as follows:

• Inputs A = 0, B = 0:
• Both PMOS transistors (PA and PB) are ON, pulling the output high.
• Both NMOS transistors (NA1 and NB1) are OFF, and the bipolar transistors (Q1 and Q2) are also OFF.
• The output remains high.
• Inputs A = 0, B = 1 or A = 1, B = 0:
• One PMOS transistor is ON, and the other is OFF, keeping the output high.
• One NMOS transistor is ON, and the other is OFF, ensuring the output remains high.
• The bipolar transistors (Q1 and Q2) are OFF.
• The output remains high.
• Inputs A = 1, B = 1:
• Both PMOS transistors are OFF.
• Both NMOS transistors are ON, pulling the output low.
• The bipolar transistors (Q1 and Q2) are ON, providing additional current drive to the output.
• The output is low.

Advantages:

The BiCMOS NAND gate offers several benefits:

• High-Speed Operation: The inclusion of BJTs allows for faster switching speeds compared to standard CMOS gates.
• Low Power Consumption: The CMOS components ensure that the gate consumes minimal power during steady-state operation.
• Improved Drive Capability: The bipolar transistors enhance the gate’s ability to drive larger capacitive loads effectively.

For a visual demonstration and further understanding of BiCMOS NAND and NOR gate design and simulation, you may find the following video helpful:

videoDesign & Simulation of BiCMOS NAND and NOR Gateturn0search8