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What is CMOS pass-transistor logic?
A popular and widely-used alternative to complementary CMOS is pass-transistor logic, which attempts to reduce the number of transistors required to implement logic by allowing the primary inputs to drive gate terminals as well as source/drain terminals.
What is TTL and CMOS logic?
Standard commercially available digital logic gates are available in two basic families or forms, TTL which stands for Transistor-Transistor Logic such as the 7400 series, and CMOS which stands for Complementary Metal-Oxide-Silicon which is the 4000 series of chips.
Is TTL logic still used?
The term “TTL” is applied to many successive generations of bipolar logic, with gradual improvements in speed and power consumption over about two decades. The most recently introduced family 74Fxx is still sold today (as of 2019), and was widely used into the late 90s.
How is a CMOS transistor used in a digital circuit?
The vast array of MOSFET-based digital circuitry is built around the CMOS inverter. This simple yet extremely effective circuit uses the combination of an NMOS transistor and a PMOS transistor to generate output signals that are, under normal operating conditions, always either logic high or logic low.
Which is the best description of pass transistor logic?
Pass-transistor logic (PTL), also known as transmission-gate logic, is based on the use of MOSFETs as switches rather than as inverters. The result is (in some cases) conceptual simplification, but the CMOS inverter’s strict logic-high/logic-low output characteristic is lost.
What’s the difference between CMOS and conventional logic?
By contrast, conventional CMOS logic switches transistors so the output connects to one of the power supply rails, so logic voltage levels in a sequential chain do not decrease. Simulation of circuits may be required to ensure adequate performance.
How are NMOS and PMOS transistors used in a transmission gate?
This technique uses the complementary properties of NMOS and PMOS transistors. i.e. NMOS devices passes a strong ‘0’ but a weak ‘1’ while PMOS transistors pass a strong ‘1’ but a weak ‘0’. The transmission gate combines the best of the two devices by placing an NMOS transistor in parallel with a PMOS transistor as shown in Figure below.