this charge pump to make a bigger voltage from a small voltage.
The RF tag takes small voltage from the air and make it bigger with the charge pump so the ic will work.
To step up from AC (example, mains) then it's handy to use a voltage multiplier (capacitors and diodes). It can use conventional components.
To step up several times from a few volts DC (example, battery), it needs to be chopped into pulses. If the next stage is a voltage multiplier then you lose a bit due to diode drops. So there's an argument for using a coil-switching topology.
A voltage multiplier normally outputs a particular voltage depending on how many stages you add. A switched coil can be adjusted to a desired volt level using various adjustments.
Coil-based methods require more experimenting if you do it yourself.
The only difference in voltage multiplier schemes I'm aware of is in the placement of capacitors, that can be either parallel or series connected. The diodes are always series connected.
The different capacitor connection schemes aren't a big thing in my opinion. Series connection can be usually found for high voltages rectifier cascades to reduce the individual voltage rating. For signal level multiplying rectifiers, parallel circuit allows lower values, which is particularly an advantage with integrated MOS capacitors. Both circuits are more or less equivalent.
Your question title is asking for when to use multipliers. It depends on the available RF voltage/current and supply requirement of your circuit. There's always an impedance matching aspect involved. To succesfully apply voltage multipliers, the source impedance must be sufficiently low.
I don't see a difference between "charge pumps" and "voltage multpliers" so far. It looks like both terms are used for the same thing.
Not necessarily. In your link, the voltage multiplying rectifier is e.g. called "charge pump".As far as I know, chargepumps are dc-dc converters and Voltage multipliers are ac-dc converters like rectifiers.
Hi Shaikss,
You see the difference of generation of voltages in Charge pump and regulators. Charge pumps use current and capacitors to build voltage level, while Regulators (linear/switched) use output voltage regulation. ( what is regulation?)( this may be voltage or current controlled).
Charge pump have certain advantage:
1. simple circuitry
2. due to V-I converter, Charge pumps reduces stability problem. ( we can say Charge pumps are more controlled)
If you replace the double-throw switch in the Micrel "charge pump" by an AC voltage source, it's a standard voltage doubling cascade rectifier. It has also names like Cockcroft-Walton or Greinacher multiplier. So where's the principle difference?
Another option for different charge pump implementations is to use synchronous rectifiers (switches) instead of diodes. But the basic operation is still the same.
In my opinion, trying to relate these arbitrarily used names to circuit differences leads to nothing...
You can't conclude a real difference from just the definition in a Wikipedia article.So a charge pump is not the same as a conventional voltage doubler.
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?