Renesas promotes work on power-saving micros

Yano pointed out there is one big problem with today’s microcontrollers: “their power efficiency remains above 100µW/MHz, which is ten times higher than energy harvesters can conveniently produce”. According to Yano, Renesas is focusing its power-saving efforts in three places. One is to make clock generators that can wake up much faster than those used today – so that they settle to 1 per cent of nominal within one clock cycle. This will reduce the amount of energy wasted while the processor waits for the clock to settle. The second method is part of a more widespread trend: to make more use of power-gated islands in both logic circuits and memories. The third proposed technique is to construct voltage converters that are optimised for low-power domains. Wireless communications are also changing in response to energy demands. Yano pointed to the development of on-off keying (OOK) as a way to cut out power-hungry synthesiser circuits. For very short range communications, Renesas is working on what it calls bit-error-rate modulated (BERM) radios, described in a paper at the IEEE Symposium on VLSI Circuits last June.