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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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