clipper circuit

A circuit which removes the peak of a waveform is known as a clipper. A negative clipper is shown in Figure

This schematic diagram was produced with Xcircuit schematic capture program. Xcircuit produced the SPICE net list Figure , except for the second, and next to last pair of lines which were inserted with a text editor.

*SPICE 03437.eps
* A K ModelName
D1 0 2 diode
R1 2 1 1.0k
V1 1 0 SIN(0 5 1k)
.model diode d
.tran .05m 3m
.end

Clipper: clips negative peak at -0.7 V.

During the positive half cycle of the 5 V peak input, the diode is reversed biased. The diode does not conduct. It is as if the diode were not there. The positive half cycle is unchanged at the output V(2) in Figure . Since the output positive peaks actually overlays the input sinewave V(1), the input has been shifted upward in the plot for clarity. In Nutmeg, the SPICE display module, the command “plot v(1)+1)” accomplishes this.


V(1)+1 is actually V(1), a 5 Vptp sinewave, ofset by 1 V for display clarity. V(2) output is clipped at -0.7 V, by diode D1.

During the negative half cycle of sinewave input of Figure , the diode is forward biased, that is, conducting. The negative half cycle of the sinewave is shorted out. The negative half cycle of V(2) would be clipped at 0 V for an ideal diode. The waveform is clipped at -0.7 V due to the forward voltage drop of the silicon diode. The spice model defaults to 0.7 V unless parameters in the model statement specify otherwise. Germanium or Schottky diodes clip at lower voltages.

Closer examination of the negative clipped peak ) reveals that it follows the input for a slight period of time while the sinewave is moving toward -0.7 V. The clipping action is only effective after the input sinewave exceeds -0.7 V. The diode is not conducting for the complete half cycle, though, during most of it.

The addition of an anti-parallel diode to the existing diode in Figure yields the symmetrical clipper in

Figure .

*SPICE 03438.eps
D1 0 2 diode
D2 2 0 diode
R1 2 1 1.0k
V1 1 0 SIN(0 5 1k)
.model diode d
.tran 0.05m 3m
.end

Symmetrical clipper: Anti-parallel diodes clip both positive and negative peak, leaving a ± 0.7 V output.

Diode D1 clips the negative peak at -0.7 V as before. The additional diode D2 conducts for positive half cycles of the sine wave as it exceeds 0.7 V, the forward diode drop. The remainder of the voltage drops across the series resistor. Thus, both peaks of the input sinewave are clipped in Figure
The net list is in Figure


Diode D1 clips at -0.7 V as it conducts during negative peaks. D2 conducts for positive peaks, clipping at 0.7V.

The most general form of the diode clipper is shown in Figure . For an ideal diode, the clipping occurs at the level of the clipping voltage, V1 and V2. However, the voltage sources have been adjusted to account for the 0.7 V forward drop of the real silicon diodes. D1 clips at 1.3V +0.7V=2.0V when the diode begins to conduct. D2 clips at -2.3V -0.7V=-3.0V when D2 conducts.

*SPICE 03439.eps
V1 3 0 1.3
V2 4 0 -2.3
D1 2 3 diode
D2 4 2 diode
R1 2 1 1.0k
V3 1 0 SIN(0 5 1k)
.model diode d
.tran 0.05m 3m
.end

D1 clips the input sinewave at 2V. D2 clips at -3V.

The clipper in Figure does not have to clip both levels. To clip at one level with one diode and one voltage source, remove the other diode and source.

The net list is in Figure

The waveforms in Figure show the clipping of v(1) at output v(2).


D1 clips the sinewave at 2V. D2 clips at -3V.

There is also a zener diode clipper circuit in the “Zener diode” section. A zener diode replaces both the diode and the DC voltage source.

A practical application of a clipper is to prevent an amplified speech signal from overdriving a radio transmitter in Figure . Over driving the transmitter generates spurious radio signals which causes interference with other stations. The clipper is a protective measure.


Clipper prevents over driving radio transmitter by voice peaks.

A sinewave may be squared up by overdriving a clipper. Another clipper application is the protection of exposed inputs of integrated circuits. The input of the IC is connected to a pair of diodes as at node “2” of Figure . The voltage sources are replaced by the power supply rails of the IC. For example, CMOS IC’s use 0V and +5 V. Analog amplifiers might use ±12V for the V1 and V2 sources.

REVIEW
A resistor and diode driven by an AC voltage source clips the signal observed across the diode.
A pair of anti-parallel Si diodes clip symmetrically at ±0.7V
The grounded end of a clipper diode(s) can be disconnected and wired to a DC voltage to clip at an arbitrary level.
A clipper can serve as a protective measure, preventing a signal from exceeding the clip limits.

One thought on “clipper circuit

  1. Clipper (electronics)
    A clipping circuit consists of linear elements like resistors and non-linear elements like junction diodes or transistors, but it does not contain energy-storage elements …
    Thus a clipper circuit can remove certain portions of an arbitrary waveform near the positive or negative peaks. Clipping …
    In the first circuit, the voltage is clipped to the reverse breakdown voltage of the zener diode. In the second, it is limited to the reverse breakdown voltage plus …
    Types – Application – Classification – See also
    http://en.wikipedia.org/wiki/Clipper_(electronics)

    Clipper Circuit
    A clipper circuits clips a fraction of its input signal keeping the remaining part of the signal unchanged. The circuits consists of resistor R , diode D, and external dc source E. …
    Circuit, Electrical, notebook, clipper, Education-Colleges-and-Universities, orcad, circuit using, clippers circuits, pspice, working, positive clipper, negative clipper, circuit theory, clipping circuit, circuit tutorial …
    http://www.scribd.com/doc/7348819/Clipper-Circuit

    In this exercise, you will: ▪ Examine a positive and a negative clipper circuit. ▪ Examine a positive and a negative clamper circuit …
    2. Measure the output voltage points Vmin and Vmax. Record the values in Table 19-1. Table 19-1 Positive Clipper Circuit Data. Voltage …
    Clipper, Clamper, Detector, and RL Circuits. 2. Connect the circuit in Figure 19-9 and measure the output waveform with an oscilloscope. Draw …
    http://www.tech.purdue.edu

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>