Question

Compare series, shunt, and chopper type JFET switch.​

Answer 1

Answer:

Explanation:

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Answer 2

Answer:

By operating JFET at the cutoff and saturation areas, a FET can be employed as a switch. The greatest current flows through the FET when the VGS is zero and it works in the saturation area. As a result, it resembles a completely ON state. Similar to this, a FET operates in the cutoff area and is unable to conduct current when the applied VGS is more negative than the pinch off voltage. Consequently, the FET is completely off. A few of the configurations where the FET can be utilised as a switch are listed below.

1. JFET used as a shunt switch : The FET is turned on by working in the saturation zone when the applied VGS is zero, and its resistance is extremely low—nearly 100 ohms. VOUT= Vin * RDS/ (RD + RDS (ON)) is the output voltage across the FET. Since RD is a very big resistance, the output voltage is roughly regarded as zero.The FET operates in the cutoff region and behaves as a high resistance device when the negative voltage, which is equal to the pinch off voltage at the gate, is applied. The output voltage is then equal to the input voltage.
2. JFET used as a series switch : If the control voltage is zero, the switch is closed; if it is negative, the switch is open. The output of the FET will display the input signal when it is turned on, and the output is zero when it is turned off.
3. JFET used as a chopper switch: A switching circuit reduces the input dc voltage. A square wave ac signal with a peak value equal to the input dc voltage, VDC, is the chopper's output. A typical ac amplifier can be used to amplify this ac signal without experiencing any drift issues. The amplified dc signal can then be "peak detected" on the amplified output. A FET analogue switch is made to function like a chopper by applying a square wave to its gate. The JFET is alternatively saturated and turned off by the gate square wave, which has a negative going swing from 0 V to at least VGS (off). This output voltage is a square wave that alternately ranges from +VDC to zero volts.

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