Party time for really outside the box thinking
Reading, UK 18 March 2021. Sondrel is designing its first radiation-hard (Rad-Hard) chip for a customer which is due to tape out shortly. The satellite modem will be used in communication satellites and therefore has to be able to withstand the challenges of the high levels of ionising radiation found in orbit that can cause glitches.
Graham Curren, Sondrel’s CEO, said, “The customer came to us because quality and reliability are paramount for a chip that goes into space. It has to work correctly all the time as you can’t get an engineer to swap it over if a problem occurs. Our work on functional safety for chips that are used in mission critical applications in cars and planes means we understand how to design for all eventualities. It takes really outside the box thinking to imagine what could possibly go wrong and design solutions should that occur. The engineers really enjoy the brainstorming sessions to come up with unusual scenarios and solving them as it stretches their imaginations in a very rewarding way. In pre-COVID days, those session were like a party game with everyone chipping in ideas over pizzas.”
Kirthi Kishore, Staff Engineer Level 3 at Sondrel office in Hyderabad, India, added, “Neither the process nor the cells and IP are specially designed to be radiation hardened. The key is to build in redundant logic in case of damage or to take over while an affected part is rebooted. In the case of the ARM 853 processor at the heart of the chip, the design has to ensure that the processor reboots correctly if a hard reset is needed due to a radiation event.”
Eshwar Rao Thelaga Thothi, who is a Physical Design Engineering Manager at Hyderabad, explained, “Incorporating these Rad-Hard requirements into Chip-Implementation and signoff flows is quite interesting as we get to see the impact of Rad-Hard cells in cell placement and also its effect in overall chip performance.”
The design is for the 22nm GlobalFoundries process which is less susceptible to radiation than smaller nodes. It has an area of 200 mm2 with 15 IP blocks with over 46 million instances.
