AMICSA 2018

A rad-hard systems-on-chip solution for close-loop motor control

19 Jun 2018, 12:10

25m

Oral Radiation-hardened technologies for analogue and mixed-signal ICs Space Applications

Speaker

Dr Ying Cao (MAGICS Instruments)

Description

This paper describes the design and implementation of a systems-on-chip solution for close-loop control of remote-handling robotic tools in radiation environment. The original intended application of the development is for remote handling equipment at ITER (a first-of-kind Tokamak fusion nuclear plant). Front-end electronics that located close to sensors and actuators on ITER remote handling systems will face gamma radiation up to 300 Gy/h and a total dose of 1 MGy, and total neutron fluence up to 10¹⁵ n/cm². Hence those electronics are required to be radiation-hardened against total-ionizing-dose (TID) radiation, as well as single-event effects (SEE) caused by neutrons (14 MeV). In order to broaden the application scope of the system, the chips were also designed to be resistant against higher energy particles (e.g., >60 MeV protons and heavy ions). The close-loop motor control system consists of five ASICs:

• A resolver/LVDT to digital converter to read out angle information from a resolver or linear distortion information from a LVDT.
• A resistive bridge sensor signal conditioning ASIC to read out sensors such as RTD, thermocouple, and strain gauge.
• A 24V 10-channel limit switch conditioning ASIC to read the status of limit switches connected to it.
• A 24V 10-channel relay driver ASIC to drive high-side solid-state or mechanical relays.
• A bus communication ASIC to implement the BiSS interface protocol, the SPI master protocol, and the RS485 bus transceiver.

Those ASICs are implemented in two commercial CMOS technologies: a low-voltage 65nm CMOS process and a 0.35µm high-voltage CMOS process. Radiation-hardened-by-design (RHBD) techniques are used in the design of the ASICs to against both TID and SEE, such as:

• use dynamic compensation techniques to mitigate radiation-induced performance drifts;
• use enclosed-layout transistors to reduce radiation-induced leakage currents;
• use guard-rings to mitigate inter-device leakage;
• use radiation-aware transistor sizing to limit radiation-induced threshold voltage shift;
• use guard-rings and of abundant contacts for all wells to mitigate single-event-latchup;
• use triplication and voting for all digital circuits to mitigate single-event-upset;
• use averaging and filtering in analog circuits to reduce single-event-transient.

The potential space applications of the close-loop motor control system could be:

• control of remote handling manipulators and remote operated vehicles;
• speed control of reaction wheels;
• control of electrical propulsion system;
• altitude control of spacecraft and satellites;
• control of electrical valves.

Presentation materials

Paper

MAGICS_AMICSA_2018_v3.pdf

Slides

magics_amicsa2018_ppt

magics_public

Peer reviewing

Paper

Accepted on 11 Jun 2018 by Boris Glass

MAGICS_AMICSA_2018.pdf