Toshiba Launches Bluetooth® low energy SoC with 3.2mA Receive and 3.5mA Transmit Current Consumption
Toshiba
(TOKYO:6502) has developed Bluetooth® low energy 1
System-on-Chip (SoC) compliance with version 4.2 that reduces current to
50% that of current products2 for IoT devices driven by a
small-sized coin cell lithium battery. By adopting an architecture
configuration and analog circuit design suited to low power operation,
current consumption of 3.2mA for receive (RX) and 3.5mA for transmit (TX)3
are achieved, considerably lengthening battery life. The SoC also
integrates RF (Radio Frequency)4 matching networks, reducing
the number of external components and contributing to downsizing of IoT
devices. This technology will be presented at the 2016 IEEE Asian
Solid-State Circuits Conference (A-SSCC) in Toyama, Japan, on November 8.
Recent rapid advances in IoT have realized wearable multi-functional IoT
devices, such as smart watches and smart bands, that collect and manage
a wide range of sensor information. Bluetooth® low energy,
developed specifically for low-power wireless communications, is used in
many IoT devices to cut weight and extend battery life. In general,
there is a trade-off between current consumption and radio
performance—receiver sensitivity and transmission power—and
conventional Bluetooth® low energy SoC cannot satisfy
both requirements at once. In order to use various types of usable
batteries in wearable IoT devices, a Bluetooth® low
energy SoC with low current consumption, in the range of 3-4mA, is a
major requirement. Although it is effective to include external
components in a Bluetooth® low energy SoC to shrink the
size of the Bluetooth® low energy device, degradation of
receiver sensitivity and transmission power of a Bluetooth®
low energy SoC with built-in RF matching networks remains a problem, due
to loss mismatch.
Toshiba has introduced three techniques to reduce Bluetooth®
low energy SoC current consumption: (1) a receiver architecture
configuration suitable for low current consumption; (2) a highly
efficient power management system; and (3) low current RF design.
-
(1) The receiver architecture introduces a local synthesizer that
employs a frequency half that of a conventional receiver, reducing
current consumption in the local oscillator. Although the architecture
tends to be vulnerable to interference signals because of its complex
frequency configuration, a high tolerance to interference is achieved
by adopting frequency planning that can avoid folding from cellular
signals.
-
(2) In order to improve power loss in the regulators (LDO: Low Drop
Out)5, LDOs are eliminated from the SoC. As performance
degradation due to switching noise from a DC-DC converter is a
concern, a phase locked loop6 is used to fix the switching
frequency of the DC-DC converter and prevent interference with the
band used by the Bluetooth® low energy.
-
(3) In low current RF design, so that TX and RX can share a single
voltage controlled oscillator (VCO), the frequency tuning range of the
VCO must be significantly wide, which increases current consumption.
By dividing the VCO for the TX and the RX to narrow the required
frequency tuning range for each VCO, low current consumption is
achieved. In addition, a switching amplifier technique is introduced
in the power amplifier to reduce current consumption.
By adopting these low current techniques, Toshiba’s Bluetooth®
low energy SoC reduces operating current consumption, to 3.2mA for the
RX and 3.5mA for the TX while improving radio performance; in the RX
sensitivity is −93 dBm and output power 0 dBm. Furthermore, by
integrating all RF matching networks in the SoC, which is fabricated
with the 65 nm CMOS process, the external component count can be reduced
to seven from the 19 required by Toshiba’s current product.
Toshiba will adopt this new current consumption technology in Bluetooth®
low energy products scheduled to start mass production this December7.
[1]: The Bluetooth® word mark and logos are registered
trademarks owned by the Bluetooth SIG,
[2]: Compared to Toshiba’s “TC35667FTG”.
[3]: The world lowest current consumption on July 11, 2016; Toshiba
survey.
[4]: Frequency used in wireless communication
[5]: A regulator that can be operated even with only a small difference
in voltage between input and output
[6]: Electronic circuitry to synchronize the phase and frequency of the
input and output signal by the feedback control.
[7]: Engineering samples have been available since October 2016.
About Toshiba Corporation
Toshiba Corporation, a Fortune
Global 500 company, channels world-class capabilities in advanced
electronic and electrical product and systems into three focus business
fields: Energy that sustains everyday life, that is cleaner and
safer; Infrastructure that sustains quality of life; and Storage
that sustains the advanced information society. Guided by the principles
of The Basic Commitment of the Toshiba Group, “Committed to People,
Committed to the Future”, Toshiba promotes global operations and is
contributing to the realization of a world where generations to come can
live better lives.
Founded in Tokyo in 1875, today’s Toshiba is at
the heart of a global network of 550 consolidated companies employing
188,000 people worldwide, with annual sales surpassing 5.6 trillion yen
(US$50 billion). (As of March 31, 2016.)
To find out more about
Toshiba, visit www.toshiba.co.jp/index.htm
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