Optimize the power of always-on logic with SESAME NTV library in TSMC 55 uLP / uLP-eF process

Jan 24, 2016

Optimize the power of always-on logic with SESAME NTV library in TSMC 55 uLP / uLP-eF process

Portable devices, like Wearables or Smart devices, spend most of their time (> 98%) in deep-sleep/Hibernate mode. It thus is crucial to minimize the energy drawn by the always-operating functions, i.e. the always-on domain, in order to extend battery lifetime. Indeed, even if the always-on logic represents usually a small part of the SoC, its weight in the overall power consumption can be very significant.

Minimizing by 60% the power consumption of the logic embedded in the always-on domain is now achievable thanks the extremely low-voltage SESAME NTV library. This library benefits from a patented flip-flop to reliably operate at the lowest voltage – down to 0.55 V +/- 10% in 55 nm uLP/uLP eF.

Power saving

The capability to operate the logic in the always-on domain down to the minimum data retention voltage of the RAM – i.e. 0.55 V +/- 10% in 55 nm uLP/uLP eF – also simplifies the power management network that translates into further power savings. The same voltage regulator can indeed be shared between the power islands in retention mode and the logic in the always-on domain.

Diagram A.O. LOGIC

The SESAME NTV is available for different VTs and provided with a full set of level shifters and isolation cells to enable safe interconnections with the Rest-of-SoC.
The librarie SESAME NTV is characterized on demand at any voltage, between 1.2 V and 0.55 V to reach the speed target with the lowest power consumption. Logic designs that operate at a few tens of kHz, like an RTC at 32kHz, may easily operate at the lowest voltage, 0.75 V may be preferred for logic block needing to run at a few MHz, like a wake-up trigger for Voice Activity Detection (VAD).

This standard-cells library is part of a consistent offering of Silicon IP products dedicated to the implementation of the Always-On domain:

  • Low-power and low BoM voltage regulators
  • Ultra low-power RC and crystal oscillators
  • Ultra low power voltage trigger
  • Low-power Voice Activity Detector

This standard-cell library is also proposed as part of a complete offering of Foundation IPs for achieving the lowest power consumption whatever the power modes of the SoC:

  • The SpRAM RHEA ERS memory generator combines very low power consumption with high density and embeds extinction and retention switches
  • SESAME HD is a 6 tracks high density standard cell library
  • CLICK is a fabric for safely implementing any power islands…

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