To remember which way the dc level of a signal moves, look at figure shown below. Notice that the diode arrows point downward, the same direction as the dc shift . Negative Clamping Circuit Similarly in the figure shown below, the diode arrow points upward, again the same direction as the dc shifts. It means that, when the diode points upward. We have a positive dc clamper and when the diode points downward, the circuit is a negative dc clamper. Positive Clamping Circuit Merits: Clamping switching technology offers a solution showing modern high-power IGBTs. Keeps your circuit from blowing up on overvoltage. Usage: Clamping can be used to adapt an input signal to a device that cannot make use of or may be damaged by the signal range of the original input. 47
Clamping circuits were common in analog television receivers. Result: Hence, we performed the clamper circuit on multisim and checked the response for the positive clamper circuit ant negative clamper circuit. Experiment No: 11 Objective: Analysis of Clamper parallel Circuits 48
Theoretical Background: A clamping circuit is used to place either the positive or negative peak of a signal at a desired level. The dc component is simply added or subtracted to/from the input signal. The clamper is also referred to as an IC restorer and ac signal level shifter. A clamp circuit adds the positive or negative dc component to the input signal so as to push it either on the positive side, as illustrated in figure (a) or on the negative side, as illustrated in figure (b). The circuit will be called a positive clamper, when the signal is pushed upward by the circuit. When the signal moves upward, as shown in figure (a), the negative peak of the signal coincides with the zero level. The circuit will be called a negative clamper, when the signal is pushed downward by the circuit. When the signal is pushed on the negative side, as shown in figure (b), the positive peak of the input signal coincides with the zero level. Statement: Design a circuit that will convert a 50% duty cycle square wave that goes from – 3V to + 3V to a 50% duty cycle square wave that goes from 0V to – 6V (+/- 0.5V). Circuit Diagram: Figure 13 Procedure: The values for the resistor R and capacitor C should be determined from the time constant equation of the circuit, t = RC. The values must be large enough to make sure that the voltage across the capacitor C does not change significantly during the time interval the diode is non- 49
conducting. In a good clamper circuit, the circuit time constant t = RC should be at least ten times the time period of the input signal voltage. For a clamping circuit at least three components — a diode, a capacitor and a resistor are required. Sometimes an independent dc supply is also required to cause an additional shift.
You've reached the end of your free preview.
Want to read all 52 pages?
- Spring '16
- Operational Amplifier, Bipolar junction transistor