clipper clamper voltage multiplier

Diode Limiters (Clippers)Diode Limiters “clip” the positive portion (a) of the sinewave and in (b), (diode reversed), clip the negative portion (less the diode conduction voltage of 0.7V.)

Diode Limiters (Clippers)

Biased “clippers” limit the positive or negative amount of an input voltage to a specific adjustable value (VBIAS +0.7V).

This positive limiter will limit the output to VBIAS + .7V

Diode LimitersThe desired amount of limitation can be attained by a power supply or voltage divider. The amount clipped can be adjusted with different levels of VBIAS.

This positive limiter will limit the output to VBIAS + .7V

The voltage divider provides the VBIAS . VBIAS =(R3/R2+R3)VSUPPLY

See Ex. 2-11 pg.74

Diode Clampers (DC Restorers)A diode clamper adds a DC level to an AC voltage. The capacitor charges to the peak of the supply minus the diode drop. Once charged, the capacitor acts like a battery in series with the input voltage. The AC voltage will “ride” along with the DC voltage. The polarity arrangement of the diode determines whether the DC voltage is negative or positive.

0V.

Diode Clampers (DC Restorers)Applications:

Amplifiers of all types use capacitive coupling between stages. Why?

To simplify the DC biasing; allows stage by stage independent biasing.

This capacitive coupling “loses” the DC component, stage to stage. To “restore” DC, the Diode Clamper can be used.

Here is a –DC Restorer circuit

Voltage Multipliers

Clamping action can be used to increase peak rectified voltage. Once C1 and C2 charges to the peak voltage they act like two batteries in series, effectively doubling the voltage output. The current capacity for voltage multipliers is low.

Voltage Doubler

Voltage MultipliersThe full-wave voltage doubler arrangement of diodes and capacitors takes advantage of both positive and negative peaks to charge the capacitors giving it more current capacity. Voltage triplers and quadruplers utilize three and four diode-capacitor arrangements respectively.

Voltage Multipliers - TriplersThe voltage tripler arrangement adds another diode/capacitor set. + half-cycle: C1 charges to Vp through D1,

- half-cycle: C2 charges to 2Vp through C2, Next + half-cycle: C3 charges to 2Vp through C3. Output is across C1 & C3.

Voltage Multipliers - QuadruplersThe voltage tripler arrangement adds another diode/capacitor set. + half-cycle: C1 charges to Vp through D1,

- half-cycle: C2 charges to 2Vp through C2, Next + half-cycle: C3 charges to 2Vp through C3. Next - half-cycle: C4 charges to 2Vp through C4 Quadruple Output is across C2 & C4.

Clippers

• A clipper is a limiting circuits;it is basically an extension of the half-wave rectifier.

clippersParallel clippers

Series clippers

Parallel Clippers

Parallel Clipper

Parallel Clipper

Diode series clipper circuits

Diode series clipper circuits

Diode series clipper circuits

Example 3.12

Example 3.12

3.5 Clamping Circuits

• A clamping circuits simply shifts the output waveform to a different dc level.

• Clampers can be classified into two type:

1. Fixed-shift clampers

2. Variable-shift clampers

Fixed-shift Clamping circuits

Fixed-shift Clamping circuits

Variable-shift clamping circuits

Variable-shift clamping circuits

Variable-shift clamping circuits

Variable-shift clamping circuits

Example 3.13

Example 3.13