Learning How to Increase Voltage Using Charge Pumps

While continuing work on the squishy message system I have also started work on my next electrical engineering project that involves working with solar technology. If you have ever read about or worked with a small solar cell, you will quickly find out that it is an inconsistent and minute power source.

The major initial challenge in working with solar is getting usable, consistent voltage. Based on my initial readings it seems like there are two ways to increase voltage. Use a properly timed inductive coil or a charge pump. I refuse to use a coil because my instinct is telling me that coils are inconsistent and will be difficult to procure consistently in quantity and similar accuracy. So the only alternative is to use a charge pump.

A charge pump is a circuit configuration containing a few or several stages depending on how much of a consistent voltage increase is needed. The basic principal works with two capacitors in proper timing. The first capacitor is charged, then its positive and negative legs are switched to make contact with a second capacitor. The second capacitor takes the charge and the process is repeated in several stages in order to produce a consistent voltage increase.

There is an excellent short paper that summarizes the basic functionality of a charge pump as well as the different types of charge pump configurations. A comparison of efficiency vs area and several other aspects are also examined. The paper is titled "A DC-DC Charge Pump Design Based on Voltage Doublers" by Januz A. Starzyk, Ying-Wei Jan, and Fengjing Qiu. I would recommend it for anyone curious about the circuit.