Parallel Clippers
Prepared By:Eng.Maira Naz
Dated:01-08-2011
Applications of diode
Applications of Diodes
 Clippers.
 Clampers.
 Peak Detectors.
 Voltage Multipliers.
 Simple Logic Gates.
 DC Power Supply.
 Filtering Circuits.
Clippers
Clippers
Clippers, limiters or clipping circuits
make use of non-linear properties of
diode, that is the diode conduct the
current in forward direction and does not
conduct in reverse direction.
Clippers
Basic operating Principle:
These circuits are primarily are wave
shaping circuits.
They clip or remove certain portion of ac
voltage applied to the input of circuit.
Clippers
Applications of Clippers:
They need to clip the voltage above or
below a certain pre-determined voltage
level arises in the television, digital
computers, radar, and many other
electronic circuits.
Clippers
Components of clipping circuits:
The clipping circuits used in electronics
are not necessarily composed of simple
diodes and resistors, they employ more
advance components to do so.
The basic principle however remains the
same.
Clippers
Steps to analyze clipper circuits.
1. Replace the diode by one of its
equivalent models.
2. Identify ON and OFF states of diodes
and clipping levels of Vin.
3. Derive the equation for transfer
characteristics of the circuit.
4. Plot the transfer characteristics and
input-output waveforms of the circuit.
Clippers
Clippers
Series Clippers
Parallel Clippers
Clippers
Further Classification:
Parallel Clippers
Unbiased Parallel
Clippers
Biased Parallel
Clippers
Clippers
Further Classification (Cont..) :
Series Clippers
Unbiased Series
Clippers
Biased Series
Clippers
Parallel Clippers
Parallel Clippers
Parallel Clippers:
The name parallel clipper stems from he
fact that the diode is in parallel with load
resistance.
Unbiased Parallel Clipper:
In parallel unbiased clipper, there ia no
battery connected in series with diode.
Unbiased parallel clippers
Parallel Clippers
Unbiased Parallel Clipper:
Fig (a) Unbiased parallel clipper
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Fig (a) shows, unbiased parallel clipper in
which diode is connected in parallel with
load resistance.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Fig (b) Input voltage waveform
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Fig (b) shows the input voltage waveform
that is going to apply at the input of the
circuit shown in fig (a).
Mathematically it is represented by the
following equation.
Vin=VmaxSinωt
Parallel Clippers
Observation for the analysis of clipping circuit:
 Vmax should be greater than 0.7V built in
potential of the silicon diode or 0.2 for
germanium.
 RL should be greater than Rin.
RL>>Rin
Or
RL~10Rin
 So, that the voltage drop across Rin can be
neglected.
Analysis of unbiased parallel
clippers with positive
clipping(Ideal diode)
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Ideal Diode:
First, we should replace the given diode
with an ideal one i.e., we should consider
the ideal model of diode.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Action during the positive half cycle:
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Action during the positive half cycle:
During the positive half cycle of the input
voltage, the diode becomes forward
biased and remains forward biased for
entire half cycle of the input.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Action during the positive half cycle:
 As ideal diode acts as short circuit when
forward biased, the current I flows entirely
through diode.
 The drop across short circuit diode is zero.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Action during the positive half cycle:
 As RL is in parallel with diode no current
flows through it and output voltage Vo=0V.
 This condition remains for entire positive
half cycle of the input.
 Thus positive half cycle gets clipped off.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Action during the negative half cycle:
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Action during the negative half cycle:
 During the negative half cycle, the diode is
reverse biased and acts as open circuit.
 The entire current flows through RL.
 So, output voltage can be found by using VDR.

Vo = Vin RL/(Rin+RL)
Where Vin= - Vm.
 Since, RL>>Rin.
 So, Rin can be neglected in comparison to RL.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Action during the negative half cycle:
So, we can also write
Vo=K Vin.
Where K=RL/ Rin+RL.
So, during negative half cycle ,
proportionate negative half cycle is
available at the output.
There exits a straight line relationship
between input and output voltage.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Output waveform:
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Transfer characteristics:
The graph of output variable against the
input variable of the circuit is called as
the transfer characteristics of the circuit.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Equation for transfer characteristics:
Transfer Characteristic equation for the
circuit shown in fig (a)
Vo=0V …..for Vi ≥ 0V
Vo=Vin RL/Rin+RL, …..for Vi < 0V
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Positive parallel Clippers:
Circuit shown in fig (a) is called as
parallel clipper with positive clipping
because it clips the positive half cycle of
input voltage.
Analysis of unbiased parallel
clippers with positive
clipping(Practical diode)
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Practical silicon diode:
Now, we consider that the diode is not an
ideal one and we must consider its 2nd
model i.e., a Vd is connected in series
with the diode.
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Practical silicon diode:
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Practical silicon diode:
Action during the positive half cycle
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Practical silicon diode:
Action during negative half cycle
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Practical silicon diode:
Input and output waveforms
Parallel Clippers
Unbiased Parallel Clipper (Cont..):
Practical silicon diode:
Mathematically, it can be expressed as
Vo=Vd …..for Vi ≥ Vd
Vo=Vin RL/Rin+RL=Vin …..for Vi < Vd
Biased parallel clipper
Parallel Clippers
Biased Parallel Clipper:
In parallel unbiased clipper, there is a
battery connected in series with diode
Parallel Clippers
Analysis of biased parallel clipper:
Ideal Diode:
Parallel Clippers
Analysis of biased parallel clipper:
Ideal Diode:
 In case of ideal diode, Vd=0V and VBB is
connected in series with diode as it is biased
parallel clipper.
 Now, the battery voltage will appear at one side
of diode and input voltage will appear across
the other side of diode.
Parallel Clippers
Analysis of biased parallel clipper:
Ideal Diode:
Diode will be the forward biased during
the time interval whenever the Vin is
greater than VBB.
Diode will be the reverse biased during
the time interval whenever Vin is less
than VBB.
Parallel Clippers
Analysis of biased parallel clipper:
Ideal Diode:
During positive half cycle
Parallel Clippers
Analysis of biased parallel clipper:
Ideal Diode:
Output waveform during negative half cycle
Parallel Clippers
Analysis of biased parallel clipper:
Ideal Diode:
During the negative half cycle
Parallel Clippers
Analysis of biased parallel clipper:
Ideal Diode:
Output waveform during negative half cycle
Analysis of different biased
parallel clippers
Parallel Clippers
Analysis of different biased parallel
clipping circuits:
Case 1:
Analysis of different biased parallel
clipping circuits (Cont..):
Transfer characteristics equation for case 1:
Vo=Vin…..for Vin < VBB i.e. Vin<2.5
Vo=VBB=2.5V…..for Vin >VBB i.e.
Vin ≥ 2.5
Parallel Clippers
Analysis of different biased parallel
clipping circuits (Cont..):
Case 2:
Parallel Clippers
Analysis of different biased parallel
clipping circuits (Cont..):
Transfer characteristics equation for case 2:
Vo=Vin…..for Vin < VBB i.e. Vin<-2.5
Vo=VBB= -2.5V…..for Vin ≥ VBB i.e.
Vin ≥ -2.5
Parallel Clippers
Analysis of different biased parallel
clipping circuits:
Case 3:
Parallel Clippers
Analysis of different biased parallel
clipping circuits (Cont..):
Transfer characteristics equation for case 3:
Vo=Vin…..for Vin >VBB i.e. Vin> 2.5
Vo=VBB= 2.5V…..for Vin ≤VBB i.e.
Vin ≤ 2.5
Parallel Clippers
Analysis of different biased parallel
clipping circuits (Cont..):
Case 4:
Parallel Clippers
Analysis of different biased parallel
clipping circuits (Cont..):
Transfer characteristics equation for case 4:
Vo=Vin…..for Vin >VBB i.e. Vin> -2.5
Vo=VBB= -2.5V…..for Vin ≤VBB i.e.
Vin ≤ -2.5