Question:
The circuit shown in the figure can be used as a ________.
The circuit shown in the figure can be used as a ________.
Show Hint
Diode in op-amp feedback = log amplifier. Output voltage is proportional to log(input current).
Updated On: Jun 23, 2025
- Full wave rectifier
- Voltage to frequency converter
- Logarithmic amplifier
- Frequency to voltage converter
Hide Solution
Verified By Collegedunia
The Correct Option is C
Solution and Explanation
Step 1: Analyze the circuit — it contains an op-amp, a diode in the feedback loop, and a resistor at the input.
Step 2: In such configurations:
The op-amp operates in inverting mode.
The diode’s exponential \( I \text{-} V \) characteristic is used to generate a logarithmic output.
Step 3: Using the diode equation: \[ I = I_s \left(e^{\frac{V_D}{nV_T}} - 1\right) \Rightarrow V_D = nV_T \ln\left(\frac{I}{I_s} + 1\right) \] Step 4: Since input voltage causes a current through the resistor, the voltage across the diode (which is the output voltage of the op-amp) is proportional to the logarithm of input voltage.
Therefore, the circuit behaves like a logarithmic amplifier.
Step 2: In such configurations:
The op-amp operates in inverting mode.
The diode’s exponential \( I \text{-} V \) characteristic is used to generate a logarithmic output.
Step 3: Using the diode equation: \[ I = I_s \left(e^{\frac{V_D}{nV_T}} - 1\right) \Rightarrow V_D = nV_T \ln\left(\frac{I}{I_s} + 1\right) \] Step 4: Since input voltage causes a current through the resistor, the voltage across the diode (which is the output voltage of the op-amp) is proportional to the logarithm of input voltage.
Therefore, the circuit behaves like a logarithmic amplifier.
Was this answer helpful?
0
0
Top Questions on Circuit Analysis
The circuit shown in figure is
- On a transmission line with standing wave the distance between a voltage maximum and adjacent current maximum is ________.
For the circuit shown in the figure, the delay of the bubbled NAND gate is 5 ns and that of the counter is assumed to be zero. If the clock (Clk) frequency is 12 MHz, then the counter behaves as a ________.
If diode cut-in voltage is 0.6 V. The diode status are
In the Op-Amp circuit, what is the load current \( I_L \)?
View More Questions
Questions Asked in AP PGECET exam
- The probability of a component being defective is 0.01. There are 100 such components in a machine. Then the probability of two or more defective components in the machine is _______
- AP PGECET - 2025
- Probability and Statistics
- A number is selected randomly from each of the following two sets:
{1, 2, 3, 4, 5, 6, 7, 8}, {2, 3, 4, 5, 6, 7, 8, 9}
What is the probability that the sum of the numbers is 9?- AP PGECET - 2025
- Probability and Statistics
- If the function \( f(z) = -x^2 + xy + y^2 + i(ax^2 + bxy + cy^2) \) of complex variable \(z = x + iy\) is analytic in the complex plane, then the values of \(a, b, c\) are _______
- AP PGECET - 2025
- Complex numbers
- Let \( f(x,y) = e^{-x} \sin(-y), g(x,y) = e^{-x} cos(-y) \), and \( C \) be the square with vertices at \( (0,0), (\frac{\pi}{2},0), (\frac{\pi}{2},\frac{\pi}{2}), (0,\frac{\pi}{2}) \). Then, the value of the line integral \( \oint_C [f(x,y)dx + g(x,y)dy] \) is _______
- AP PGECET - 2025
- Calculus
- Let \( A \) be a \(3 \times 3\) matrix and \( B = 2A^2 + A^{-1} - I \), where \( I \) is a \(3 \times 3\) identity matrix. If the eigenvalues of \( A \) are 1, –1 and 2, then the trace of \( B \) is ________
View More Questions