1. Thought of the Day There is nothing noble about being
superior to some other man.
True nobility is in being
superior to your previous self.
-- Whitney Young.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

2. Clippers and Clampers - 2
D.C. Kulshreshtha
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

3. Clippers and Clampers-2
Topics to be discussed
Parallel Clipper.
Practical Aspects of Parallel Clipper.
Defining Conditions.
Simple Parallel Positive Clipper.
Combination Clipper.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

4. Clippers and Clampers-2
Parallel Clipper
The diode is put in parallel with the load.
This too is the familiar half-wave rectifier circuit.
Input wave. The circuit. Output wave.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

5. Practical Aspects of Parallel Clipper.
If we take into account the threshold voltage,
VT = 0.7 V, the clipping level is not zero, but 0.7 V.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

6. Clippers and Clampers-2
Defining Conditions.
Small-signal diodes have small junction area, because they are optimized to work at high frequencies.
They have more bulk resistance, RB.
For example, a forward current of 10 mA at 1 V.
For above specifications, determine RB.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

7. Clippers and Clampers-2
Clipper does not work properly, unless
RB << RS << RL
We must have
100RB < RS < 0.01RL
For Example, if RB = 30 Ω, RS should be at least 3 kΩ, and RL should be at least 300 kΩ.
If this condition is satisfied, we can ignore RL in the circuit.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

8. Simple Parallel Positive Clipper
Draw the output.
The Input.
The Circuit.
The Output.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

9. Clippers and Clampers-2
Example 3
Determine the output of the parallel biased clipper for the given input.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

10. Clippers and Clampers-2
Solution
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

11. the transfer characteristic Now, draw the output wave, and get credit.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

12. Clippers and Clampers-2
Example 4
Repeat Example 3, taking a silicon diode with VT = 0.7 V, instead of an ideal diode.
Solution :
To determine transition level, we use the condition,
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

13. Clippers and Clampers-2
Applying KVL,
For inputs less than 3.3 V (including negative values), the diode is ON, and vo = 3.3 V
For inputs greater than 3.3 V, the diode is OFF, and
vo = vi
as shown in figure.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

14. Clippers and Clampers-2
Draw the output,
and get credit.
Note that VT reduces Vi(tr) to 3.3 V from 4 V.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

15. Clippers and Clampers-2
Design Problem
You are given
PN-Junction diodes (assumed ideal),
Resistors,
Two batteries of 1.5 V each, and
A sinusoidal voltage source.
Design a circuit that gives an output as
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

16. Clippers and Clampers-2
Solution
D1 clips off positive parts above the positive bias level.
D2 clips off below negative level.
This circuit is called a combination clipper.
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2

17. Applications of Combination Clippers
If the input voltage is very large compared to the bias level, the output signal is a SQUARE WAVE.
Thus, the circuit can be used for wave-shaping.
It can also be used in a completely different way, as a limiter used to protect a sensitive circuit (e.g., OP-AMP, Galvanometer).
The diodes conduct only when something abnormal happens.
Sensitive
Circuit
मंगलवार, 30 अप्रैल 2019
Clippers and Clampers-2