BiCMOS: Basics, Advantages, and Disadvantages

This page explores the fundamentals of BiCMOS (Bipolar Complementary Metal-Oxide-Semiconductor) technology, its advantages, and disadvantages. We’ll also delve into BiCMOS devices, including inverters, gates, and drivers.

BiCMOS is a logic family that cleverly combines both bipolar and CMOS logic devices within a single integrated circuit (IC). This combination leads to several benefits:

• High Speed of Operation: BiCMOS circuits can switch very quickly.
• High Packing Density: More components can be packed into a smaller space compared to purely bipolar designs.
• Low Power Dissipation: BiCMOS uses less power than comparable bipolar circuits.

The key difference lies in leveraging the strengths of both technologies. BiCMOS offers advantages over conventional CMOS and Bipolar logic families by combining their best attributes.

BiCMOS Advantages

Here’s a summary of the advantages BiCMOS brings to the table:

• Low Power Dissipation: It dissipates less power compared to bipolar circuits.
• Improved Speed of Operation: It offers faster switching speeds compared to CMOS circuits.
• Large Current Drive: It can drive larger currents than CMOS circuits.

BiCMOS Disadvantages

Of course, there are also downsides to consider:

• High Cost: BiCMOS fabrication is generally more expensive.
• Longer Fabrication Time: The manufacturing process requires more mask stages, leading to a longer fabrication time.

BiCMOS Devices: Inverters, Gates, and Drivers

BiCMOS circuits utilize active devices like NMOS, PMOS, NPN BJTs (Bipolar Junction Transistors), and lateral PNP BJTs.

BiCMOS Inverters

Figures 1 through 3 depict various types of BiCMOS inverters.

Figure 1 shows resistive shunt type and active shunt type inverters.

Figure 2 shows Simple R-type BiCMOS inverter and R-type active BiCMOS inverter types.

Figure 3 shows feedback type BiCMOS and parallel output CMOS (collector emitter shunting) type of inverters.

BiCMOS Gates

Figure 4 illustrates a BiCMOS NAND gate.

BiCMOS Drivers

Figure 5 depicts Gated diode, modified gated diode and emitter follower types of BiCMOS drivers.