cmos and bicmos
BICMOS ( BJT as op stage->Higher switching speed
)ckts have better speed compared to CMOS ckts and is well suited for I/O intensive applications
High impedance CMOS transistors may be used for the input circuitry while the remaining stages and output drivers are realized using bipolar transistors.
MOS speed depends on device parameters such as saturation current and capacitance. These in turn depend on oxide thickness, substrate doping and channel length.
Compared to CMOS, BiCMOS’s reduced dependence on capacitive load and the multiple circuit and I/Os configurations possible greatly enhance design flexibility and can lead to reduced cycle time
Peak bipolar speed is less dependent on circuit capacitance
Other important thing is that
BiCMOS circuits are used in cases of large current requirements. Since the output stage here is BJT who are capable of carrying large currents. CMOS used for low power circuits.
Refer->
**broken link removed**
Hope this helps!
-Hemanshu