INTRODUCTION• Some of the non linear function circuits are : CLAMPERS CLIPPERS PEAK DETECTORS
CLAMPING CIRCUITS The clamping circuits in general, designed “clamp” the top or bottom of a waveform. Fixed d.c. level, which may be zero, while preserving its shape and amplitude The distinguishing feature of a clamper is that is it adjusts the d.c. level without needing to know the exact waveform.
• Zero volts-waveforms
Operation of the circuit : input voltagevi = vm sin ω t and vrefInterval 0 ≤ ω t ≤ π : Vi is positive, Vd is negative V0 is negative the diode is reverse biased. No current flows through the capacitor i.e. it is not charged.Interval π ≤ ω t ≤ 3 π/2 : Vi is negative V0 is positive. The diode conducts and the NV terminal of the op amp behaves as virtual ground. The capacitor c1 gets charged with point A at a potential higher than that of point be the capacitor gets charged to the peak value Vm of the input voltage.
Interval ω t > 3π/2 : Vd = - (Vm + Vi) = -Vm (1+sin ωt )And diode D is OFF. As a result the output voltage. V0 = - Vd = Vm (1+sin ωt )Reference voltage the capacitor gets charged to (Vm +vref ) the output voltage. V0 = Vm sin ωt + (Vm +vref )
Examples : Vm = 10 v and Vref = 5v V0 = 10 sin ωt +10+5 = 10 sin ωt + 15
Waveforms for +vref and –vref :
CLIPPER Clipper are circuits which can clipp off a portion of the input waveform without distorting the rest of the waveform. Clipping circuits are also refer limiter amplitude selectors or slicers.
POSITIVE CLIPPER : Precession diode which can be used to slice off a portion of the positive half of the input signal. The level at which clipping is done is determined by the reference voltage.
Positive clipper :
Positive clipper waveforms :
NEGATIVE CLIPPER : Reversed and the reference voltage the resulting circuit is a negative clipper circuit. it clips OFF the negative region of the input signal waveform below the reference voltage.
Negative clipper circuit :
Negative clipper waveforms :
PEAK DETECTORSDetector : The maximum value is called detectorPeak detectors : Peak detectors ate electronic circuits that track the input signal faithfully until it detects a peak and holds that value until a new, Larger peak is detected.
Basic peak detector : The diode allows un directional current to charge the capacitor. The capacitor stories the charge and acts as a voltage memory. It holds the peak value of the input voltage. To detect a peak, S1 has to be closed and S2 open. To hold the peak value both the switches should be open. To reset the circuit, S1 has to be opened and S2 closed.