A fully integrated negative output voltage charge pump for implantable single photon imagers

In this brief, a fully integrated inverting voltage converter for biasing complementary metal-oxide-semiconductor integrated single-photon avalanche diodes is presented. The design uses a dual-chain inverting Dickson charge pump architecture to generate a negative high voltage output from a single positive supply with a voltage gain factor larger than five, reaching a peak conversion efficiency of up to 20 %. A closed-loop controller is implemented for output stabilization. At a set output voltage of text-series-to-math-18for the used diodes, a maximum output power of text-series-to-math500with a conversion efficiency of 18 % can be achieved. Relying solely on metal sandwich capacitors, the design is resilient to continuous negative high voltage effects and can be used in medical implantable devices requiring long-term reliability. Due to the full integration of all components, it is suitable for low-power implantable medical systems and paves the way towards fully integrated, implanted in-body sensing systems using single-photon avalanche diodes that require negative high voltage biasing. This opens up new fields for uses of high precision and fluorescence imaging in portable devices, not limited to medical devices.

Subjects

biomedical

Capacitors

charge pump

Charge pumps

CMOS

Dickson

implants

Integrated circuits

inverting

Metals

negative high voltage

Single-photon avalanche diodes

SPAD

Switches

Voltage

voltage converter

DDC Class

620: Engineering

621: Applied Physics

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A fully integrated negative output voltage charge pump for implantable single photon imagers