CMOS Vs TTL

 The difference between the two Logic Styles are:

  • TTL circuits utilize BJTs while CMOS circuits utilize FETs.
  • CMOS allows a much higher density of logic functions in a single chip compared to TTL.
  • TTL circuits consumes more power compared to CMOS circuits at rest.
  •  CMOS chips are a lot more susceptible to static discharge compared to TTL chips
  • Propagation delay is more in CMOS compared to TTL
  • Switching Speed is More for TTL compared to CMOS.
  • CMOS devices are cheaper than TTL Devices. 
  • The Power Supply requirement for TTL is  3 to 15V, small fluctuations are tolerated.
  • The Power Supply requirement for CMOS is  5V ±0.25V, it must be very smooth, a regulated supply.
  • TTL Can handle only less frequency compared to CMOS.
Why CMOS is Slower compared to TTL?

Since TTL has very little parasitic capacitance, the time delay is very small, & TTL is faster.

MOSFETs, based on voltage operations, have much greater capacitances, the charging & discharging of which consumes time (Ref: RC time constant), hence CMOS is slower.

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