Combinational Logic: Schmitt-Trigger Devices

Schmitt-trigger devices
Example: VHC14

A Schmitt-trigger device has a hysteresis band between two input threshold voltages.
The following shows the input and output waveforms of a Schmitt inverter with an input threshold hysteresis.
In the case of an IC with hysteresis, the positive-going threshold voltage (VP) differs from the negative-going threshold voltage (VN). For a slowly rising or falling input, an input threshold hysteresis (VH) helps stabilize the output. Even in the presence of input noise or power supply or ground bounce due to noise, an IC does not produce a false output unless the noise or bounce exceeds the hysteresis width.

Schmitt inverter
Schmitt inverter
Input and output waveforms of a Schmitt inverter
Input and output waveforms of a Schmitt inverter

Chapter3 Basic CMOS Logic ICs

Basic CMOS Logic ICs
Combinational Logic: Inverters and Buffers
Combinational Logic: Bidirectional Bus Buffers
Combinational Logic: Decoders
Combinational Logic: Multiplexers
Combinational Logic: Analog Multiplexer/Demultiplexers
Combinational Logic: Analog Switches
Sequential Logic: Latches
Sequential Logic: Flip-Flops
Sequential Logic: Counters
Sequential Logic: Shift Registers


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