A good Sample and Hold circuit should have

1. High input impedance

2. High output impedance

3. Low input impedance 

4. Low output impedance

Sample and Hold (S/H) circuit:

It is used with an analog to digital converter to sample the input analog signal and hold the sample signal.

Circuit:-

Properties:

1. A S/H Circuit should have high input impedance and low output impedance because due to high input impedance loading effect [It is the degree to which a measurement instrument impact electrical properties (Voltage, Current, resistance) of a Circuit] is less and Circuit performance is better.

Conclusions:

for better circuit performance input impedance should be high and output impedance should be low.

Option 4 correct choice.

Additional Information

Application of sample and hold circuit

• Analog to digital converter
• Signal processing
• Filter design
• Oscilloscope