A Single-Event-Hardened Scheme of Phase-Locked Loop Microsystems for Aerospace Applications

Area of Science:

• Aerospace Engineering
• Microelectronics
• Radiation Effects

Background:

• Phase-locked loop (PLL) microsystems are crucial in aerospace but susceptible to irradiation effects.
• Single-event transients (SETs) caused by radiation can disrupt PLL performance.
• Existing hardening schemes may alter loop parameters or structure.

Purpose of the Study:

• To propose an efficient charge pump hardened scheme for PLLs using radiation-hardened-by-design (RHBD) technology.
• To reduce the sensitivity of PLL microsystems to single-event effects (SEEs) in aerospace environments.
• To verify the effectiveness of the proposed scheme through simulation.

Main Methods:

• Sensitivity analysis of SET at various charge pump nodes and bombardment energies.
• Implementation of a digital control circuit between the charge pump and low-pass filter.
• Simulation of SET effects using a double-exponential current pulse model on unreinforced and reinforced PLLs.

Main Results:

• The hardened scheme reduced transient response fluctuation by 94.2%.
• Lock recovery time increased by 75.3% after an event.
• Maximum phase shift decreased by 90.8% compared to unhardened designs.
• Simulations were performed using the SMIC 130 nm CMOS process.

Conclusions:

• The proposed RHBD charge pump hardened scheme effectively suppresses SET effects in PLL microsystems.
• The digital control circuit significantly reduces charge pump sensitivity to transients.
• The scheme enhances the reliability of PLLs for aerospace applications without altering fundamental loop parameters.