Question

A positive clamper circuit with a 10V DC source is fed with a 20V p-p sinusoidal input. What is the minimum DC voltage level at the output?

• A. \(0\text{ V} \)
• B. \(10\text{ V} \)
• C. \(20\text{ V} \)
• D. \(-10\text{ V} \)

Hint:

A positive clamper shifts the entire waveform upward so that its lowest point sits at the reference voltage level. Here, \(V_{\text{min}} = V_{\text{ref}} = 10\text{V}\).

Answer 1

The Correct Option is B

Concept: A clamper circuit is an analog diode-capacitor network that shifts the entire DC level of an incoming alternating signal without altering the original shape or peak-to-peak amplitude of the waveform.
• Positive Clamper: Shifts the input signal upward such that its lowermost peak is aligned with a specified reference voltage level.
• Reference Voltage Connection: If an independent DC voltage source \(V_{\text{ref}}\) is added in series with the diode branch, the signal is clamped such that its minimum peak matches this reference value rather than \(0\text{V}\).

Step 1: Analyzing the parameters of the input signal.
The input signal is a standard symmetrical sinusoid with a peak-to-peak voltage (\(V_{p-p}\)) of \(20\text{V}\). This means its positive and negative peak amplitudes relative to zero are: \[ V_m = \frac{V_{p-p}}{2} = \frac{20}{2} = 10\text{ V} \] The input waveform ranges from a maximum value of \(+10\text{V}\) to a minimum value of \(-10\text{V}\).

Step 2: Determining the shifted output profile using the reference voltage.
A standard positive clamper without a DC bias source shifts the minimum peak of the input signal to \(0\text{V}\). Here, a \(10\text{V}\) independent DC bias source is integrated into the circuit. This reference source forces the lower boundary (the minimum peak) of the output waveform to align with the value of the reference voltage source: \[ V_{\text{out, min}} = V_{\text{ref}} = 10\text{ V} \] Since the peak-to-peak amplitude must remain constant at \(20\text{V}\), the output waveform will vary from a minimum value of \(10\text{V}\) up to a maximum value of \(10\text{V} + 20\text{V} = 30\text{V}\). The problem specifically asks for the minimum voltage level at the output, which is exactly \(10\text{V}\). This corresponds to Option (B).