Pulse circuits - Sampling gates
Pulse circuits tutorial
Pulse Circuits - Sampling Gates
So far we have come across different pulse circuits. Sometimes we need to restrict the application of such pulse inputs to certain periods of time. The circuit that helps us in this aspect is the Sampling Gate Circuit . These are also called linear gates or transmission gates or selection circuits .
These sampling gates help to select the signal transmission within a certain time interval, for which the output signal is the same as the input signal or zero otherwise. This period is selected using a control signal or a selection signal .
For a sampling gate, the output The signal must be the same as the input or proportional to the input signalreed in a selected time interval and must be zero otherwise. This selected period is called Transmission period and the other period is called Non-transmission period . This is selected using a control signal indicated by V C . The following figure explains this point.
When the control signal V C is at V 1 , the sample gate is closed and when V C is at V 2 , it is open. The pulse width T g indicates the period during which the gate pulse is applied.
Types of sampling gates
Types of sampling gates include -
One-way sampling gates - These types of poSampling lines can pass positive or negative pulses through them. They are built using diodes.
Bidirectional sampling gate - These types of sampling gates can pass positive and negative pulses through them. They are built using diodes or BJTs.
Types of switches used
The samp gates can be built using either series or shunt switches. The period during which the switch should be open or closed is determined by the trigger pulse signal. These switches are replaced by active elements such as diodes and transistors.
The following figure shows the block diagrams of sampling gates using serial and shunt switches.
Sampling Gate using a serial switch
In this type of switch, if switch S is closed, the output will be exactly equal or proportional to the input. This period will be the Transmission Period .
If the S switch is open, the output will be zero or ground signal. This period will be the Non-Transmission Period .
Sampling gate using a shunt switch
In this type of switch, if switch S is closed, the output will be zero or one ground signal. This period will be the Non-Transmission Period .
If the S switch is open, the output will be exactly equal or proportional to the input. This period will be the Transmission Period .
Sample gates are entirely different from logic gates in digital circuits. They are also represented by pulses or voltage levels. But this soundt digital gates and their output is not an exact replica of the input. Whereas sample gate circuits are analog gates whose output is an exact replica of the input.
In the next chapters we will discuss the types of sampling gates.