A +/−25V Charge Pump with Switchable Polarity in 3.3V CMOS Technology

In this paper a scalable multiple-stage charge pump with switchable polarity constructed from low-voltage MOS transistors is demonstrated. A distinguished feature of the proposed circuit is a cross-switch integrated in each pumping unit, which configures the polarity of the respective pumping stage depending on the polarity of the preceding stage, thus implementing a daisychained control scheme. Such approach allows connecting any amount of stages in series, enabling a straightforward scalability of the circuit. A prototype switchable charge pump comprising 18 stages is implemented with 3.3 V MOSFET devices in 90 nm SOICMOS technology. The measured circuit generates output voltages exceeding <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$+/-;25 ~\mathrm{V}$</tex> from a single 1.9 V supply source while consuming a current of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$450 \mu ~\mathrm{A}$</tex>. The proposed charge pump can be used as a driver for switchable systems requiring high actuating voltages for high-ohmic inputs.