MOSFET as Switches - Data Converter Fundamentals - Analog & Mixed VLSI Design | Summary and Q&A

TL;DR

This lecture discusses the concept of discrete time circuits and sampling, using a simple sampling circuit with a switch and a Mosfet transistor as an example.

Key Insights

• ⌛ Discrete time circuits are used when the input is only available at periodic instants of time, and the output is produced at the end of each period.
• ❓ A simple sampling circuit can be created using a switch, a capacitor, and a Mosfet transistor as a switch.
• ⚡ The Mosfet transistor can conduct current in either direction by adjusting the gate voltage.

Transcript

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Questions & Answers

Q: What is a discrete time circuit?

A discrete time circuit is a circuit that processes inputs sampled at periodic intervals, producing an output at the end of each period.

Q: How does a sampling circuit work?

In a sampling circuit, a switch and a capacitor are used to sample the input signal. The switch is controlled by a clock signal, and the capacitor stores the sampled voltage.

Q: How does the Mosfet transistor serve as a switch in the sampling circuit?

The Mosfet transistor can be turned on or off by controlling the gate voltage. When the transistor is on, it allows current to flow, sampling the input signal.

Q: What are the different operating regions of the Mosfet transistor?

The Mosfet transistor can operate in either the saturation region or the triode region, depending on the voltage conditions. In saturation, it acts as a current source, while in triode, it acts as a resistor.

Summary & Key Takeaways

• The lecture introduces the concept of discrete time circuits, where the input is sensed at periodic intervals and the circuit processes each sample to produce an output.

• A simple sampling circuit is presented, consisting of a switch, a capacitor, and a Mosfet transistor as a switch.

• The switching behavior of the transistor is explained with different voltage conditions, showing how the circuit samples the input signal.