An ultra-low power receiver for an internet-of-things application wireless transceiver

Professor Sang-Gug Lee has developed a new receiver for an internet-of-things application wireless transceiver. It is the world’s first receiver capable of supporting more than -100dBm sensitivity while consuming less than 1mW of power.

Article  |  Fall 2018

Recently, everything convenient. This great phenomenon is represented by the internet of things (IoT). The IoT is a key concept that can realize future technologies, such as healthcare, smart factories, home automations, and autonomous navigation.

Minimizing the power consumption of network nodes is a big challenge to entering the IoT world. An energy-efficient node makes it possible to extend its life with batteries, to maintain a small enough size to implant it into a human body, and to reduce costs. The most power-hungry block in the node is the wireless transceiver, specifically the receiver. Consequently, the need to develop low-power receivers has been raised to realize the IoT world.

The Nano Integrated Circuit Expertise Laboratory team at the School of Electrical Engineering, KAIST, led by Professor Sang-Gug Lee, presented a novel low power receiver architecture for IoT application, which supports more than -102dBm sensitivity at 25kbps data rate with only 0.466mW power consumption. The sensitivity refers to the minimum input power at which the receiver can guarantee a certain quality of communication. Receivers with good sensitivity enable longer distance communication. Commercial wireless communication technologies, such as Zigbee, Bluetooth, and Wifi, support about -90dBm sensitivity with more than 10mW power consumption.

 

Three main concepts are used to implement the receiver. First, the current re-used low-noise amplifier (LNA) is used. To reduce the power consumption with high performance, two amplifiers are stacked under the same supply voltage. Second, the two-step frequency down conversion (called sliding-IF) architecture is adopted, while modern receivers mostly use direct conversion scheme. Thanks to this method, the power consumption for the frequency synthesis is greatly reduced. Third, two-step signal demodulation is adopted. The frequency-shifted keying (FSK) modulated signal is firstly converted to the on-off keying (OOK) signal by the complex poly-phase filter (PPF), and is then demodulated to a digital signal. This scheme facilitates more power-efficient signal filtering and high signal-to-noise property.

The research team is now developing a commercial version targeting the IoT market. Since the proposed receiver consumes extremely low power compared to other similar-performing commercial products, the research team anticipates that the technology will be a groundbreaking product in the market.