Difference between Dickson and Cockcroft walton voltage multiplier
This page compares Dickson voltage multiplier circuit vs Cockcroft walton voltage multiplier circuit and mentions difference between Dickson and Cockcroft walton voltage multiplier with their respective advantages and disadvantages.
Introduction: When RF energy travels through free space, it gets attenuated and power received at the receiver will be lower in value. Hence signal amplification is required at the receiver so that sufficient power is available to drive the load or rest of the circuit parts. Voltage multiplier or power amplifier is needed for this purpose after antenna impedance matching circuit. The advantages of voltage multiplier is that it generates higher output voltages for lower input voltage source and it does not require transformer. The disadvantage is that its output voltage drops for higher resistance values.
Both of these circuits Dickson and Cockcroft walton are used as voltage multiplier which produces output voltage greater than the applied input voltage. These circuits are composed of diodes and capacitors arranged in special configurations as shown below.
Cockcroft walton voltage multiplier circuit
The figure-1 depicts two stage Cockcroft walton voltage multiplier circuit. It is also used for low voltage to high voltage conversion.
In this multiplier circuit, all the coupling capacitors are connected in series. This configuration provides significant voltage drop under load condition when number of stages are increased. This limitation has been eliminated by dickson circuit.
Dickson voltage multiplier Circuit
The figure-2 depicts two stage dickson voltage multiplier circuit. It is used for low AC voltage to high DC voltage conversion.
This circuit arranges all the capacitors in parallel. Hence it mitigates voltage drop issue observed in previous circuit but it exhibits large capacitor voltage stress at the last multiplier stage. In order to leverage benefits or advantages of both the circuits hybrid structure have been implemented by arranging some capacitors in series and some in parallel. The other variants of dickson multiplier are dickson charge pump using CMOS technology and differential drive multiplier etc.
Refer RF energy harvesting system >> in which voltage multiplier is used.
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