Therefore, all positive voltages above +4.7 V and negative voltages below –6.7 V are automatically clipped. Diode D 2 does not conduct until the voltage reaches –6.7 V. When the voltage of the positive half cycle reaches +4.7 V, diode D 1 conducts and limits the waveform at +4.7 V. Any anode voltage levels above this bias point are clipped off. For example, if the V BIAS level is set at 4.0 volts, then the sinusoidal voltage at the diode’s anode terminal must be greater than 4.0 + 0.7 = 4.7 volts for it to become forward biased. The voltage across the series combination must be greater than V BIAS + 0.7V before the diode becomes sufficiently forward biased to conduct. To produce diode clipping circuits for voltage waveforms at different levels, a bias voltage, V BIAS is added in series with the diode to produce a combination clipper as shown. But we can increase this ☐.7V threshold to any value we want up to the maximum value, ( V PEAK) of the sinusoidal waveform either by connecting together more diodes in series creating multiples of 0.7 volts, or by adding a voltage bias to the diodes. However, due to the forward bias voltage drop across the diodes the actual clipping point occurs at +0.7 volts and –0.7 volts respectively. Then diode clipping circuits can be used to clip the positive half cycle, the negative half cycle or both.įor ideal diodes the output waveform above would be zero. If we connected two diodes in inverse parallel as shown, then both the positive and negative half cycles would be clipped as diode D 1 clips the positive half cycle of the sinusoidal input waveform while diode D 2 clips the negative half cycle. ![]() When the diode is reverse biased, no current flows through it and the voltage across its terminals is unaffected, and this is the basic operation of the diode clipping circuit.Īlthough the input voltage to diode clipping circuits can have any waveform shape, we will assume here that the input voltage is sinusoidal. We saw in the Signal Diodes tutorial that when a diode is forward biased it allows current to pass through itself clamping the voltage. ![]() Then diode clipping circuits can be used in voltage limiting applications. For example, the half-wave rectifier is a clipper circuit, since all voltages below zero are eliminated.īut Diode Clipping Circuits can be used a variety of applications to modify an input waveform using signal and Schottky diodes or to provide over-voltage protection using zener diodes to ensure that the output voltage never exceeds a certain level protecting the circuit from high voltage spikes. This diode clipping of the input signal produces an output waveform that resembles a flattened version of the input.
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