What is a sampling gate (sample-and-hold circuit)?
1 Answer
A sampling gate, also known as a sample-and-hold circuit (S/H), is an electronic circuit used to capture and store the voltage level of an input signal at a specific moment in time. It performs two main functions: sampling and holding.
Sampling: The sampling process involves capturing the instantaneous voltage level of the input signal at a precise moment, typically controlled by an external clock signal. When the sampling gate is enabled, it allows the input signal to pass through and reach the holding circuit.
Holding: Once the sampling is complete, the sample-and-hold circuit holds the voltage level at its output constant until the next sampling cycle. This means that even if the input signal changes after the sampling phase, the output of the sample-and-hold circuit remains constant until the next sample is taken.
The primary application of sample-and-hold circuits is in analog-to-digital converters (ADCs) and other systems that require precise and stable voltage level measurements. In ADCs, the sample-and-hold circuit captures the analog input voltage, which is then converted into a digital representation for processing by a digital system.
Here's a simplified explanation of how a sample-and-hold circuit works:
Sampling Phase:
The sampling gate is enabled, allowing the input signal to pass through to a capacitor.
The capacitor charges up to the voltage level of the input signal.
Holding Phase:
After the sampling phase is complete (controlled by a clock signal), the sampling gate is disabled, preventing any further changes to the capacitor's voltage.
The voltage across the capacitor is now held steady and becomes the output voltage of the sample-and-hold circuit.
Next Sampling Cycle:
When the next sampling cycle begins, the sampling gate is enabled again, and the process repeats, capturing and holding the new voltage level.
The sample-and-hold circuit's ability to "freeze" the input signal allows time for subsequent processing stages to work with a stable voltage reference, ensuring accurate and consistent results.
Sampling: The sampling process involves capturing the instantaneous voltage level of the input signal at a precise moment, typically controlled by an external clock signal. When the sampling gate is enabled, it allows the input signal to pass through and reach the holding circuit.
Holding: Once the sampling is complete, the sample-and-hold circuit holds the voltage level at its output constant until the next sampling cycle. This means that even if the input signal changes after the sampling phase, the output of the sample-and-hold circuit remains constant until the next sample is taken.
The primary application of sample-and-hold circuits is in analog-to-digital converters (ADCs) and other systems that require precise and stable voltage level measurements. In ADCs, the sample-and-hold circuit captures the analog input voltage, which is then converted into a digital representation for processing by a digital system.
Here's a simplified explanation of how a sample-and-hold circuit works:
Sampling Phase:
The sampling gate is enabled, allowing the input signal to pass through to a capacitor.
The capacitor charges up to the voltage level of the input signal.
Holding Phase:
After the sampling phase is complete (controlled by a clock signal), the sampling gate is disabled, preventing any further changes to the capacitor's voltage.
The voltage across the capacitor is now held steady and becomes the output voltage of the sample-and-hold circuit.
Next Sampling Cycle:
When the next sampling cycle begins, the sampling gate is enabled again, and the process repeats, capturing and holding the new voltage level.
The sample-and-hold circuit's ability to "freeze" the input signal allows time for subsequent processing stages to work with a stable voltage reference, ensuring accurate and consistent results.