Five-Channel Independently Floating Synchronous High-Voltage Supply for Microchannel Plates
Large-area microchannel-plate detectors for time-of-flight mass spectrometry and night-vision systems require five separately floating high-voltage domains (MCP-in, MCP-out, acceleration grid, focus electrode, and phosphor screen) at 800–2800 V with inter-channel synchronization better than ±1.8 V and ripple below 180 mV p-p while surviving 10⁻⁹ Torr vacuum and >800 krad radiation.
The supply uses five identical 180 kHz resonant flyback converters powered from a common 28 V rail, each driving its own piezoelectric transformer and four-stage multiplier potted in radiation-hardened silicone. Physical isolation >32 mm and mu-metal shielding between channels prevent crosstalk <1.2 V when one channel steps 900 V.
Synchronization is maintained by a master 40 MHz clock distributed via radiation-resistant fiber optics; each converter locks its switching phase to within ±11° of nominal, ensuring simultaneous voltage changes across all five domains during gain adjustment. Absolute voltage matching is achieved by a shared 10.000 V reference and individual 18-bit DACs calibrated at commissioning to <0.06 % differential error.
Radiation hardness uses 150 nm silicon-on-insulator control ICs with triple modular redundancy and ceramic capacitors exhibiting <0.7 % shift after 1.2 Mrad(Si). Total dose compensation adjusts DAC reference scaling every 500 hours based on integrated dose measured by on-board RADFETs.
Current limiting per channel folds back to 120 % within 1.1 µs of MCP overload, protecting plates from vacuum discharge while allowing continued operation of unaffected channels at reduced gain. Recovery implements a soft ramp over 180 ms to prevent ringing.
Gain control supports 120 dB dynamic range through simultaneous adjustment of MCP-in/out differential and focus voltage using pre-characterized look-up tables that maintain pulse-height resolution <42 % FWHM across temperature –35 °C to +70 °C.
These five-channel floating supplies routinely deliver >1.4 × 10⁸ gain with timing resolution <26 ps in 300 mm diameter TOF detectors and survive 15-year LEO missions with zero high-voltage failures.
