Ao Ba

A 1.9nJ/b 2.4GHz multistandard (Bluetooth Low Energy/Zigbee/IEEE802.15.6) transceiver for personal/body-area networks

This paper presents a multistandard ultra-low-power (ULP) 2.36/2.4GHz transceiver for personal and body-area networks (PAN/BAN). The presented radio complies with 3 short-range standards: Bluetooth Low Energy (BT-LE), IEEE802.15.4 (ZigBee) and IEEE802.15.6 (Medical Body-Area Networks, MBAN). A proprietary 2Mb/s mode is also implemented to support data-streaming applications like hearing aids. Current short-range radios for Zigbee and BT-LE typically consume more than 20mW DC power, which is rather high for autonomous systems with limited battery energy. The dual-mode MBAN/BT-LE transceiver achieves a power consumption of 6.5mW for the RX and 5.9mW for the TX by employing a sliding-IF RX and a polar TX architecture. However, it suffers from limited RX image rejection and needs a PA operating at a higher supply voltage. In this paper, an energy-efficient radio architecture with a suitable LO frequency plan is selected, and several efficiency-enhancement techniques for the critical RF circuits (e.g., a push-pull mixer and a digitally-assisted PA) are utilized. As a result, the presented transceiver dissipates only 3.8mW (RX) and 4.6mW (TX) DC power from a 1.2V supply, while exceeding all of the PHY requirements of above 3 standards.

9.8 An 860μW 2.1-to-2.7GHz all-digital PLL-based frequency modulator with a DTC-assisted snapshot TDC for WPAN (Bluetooth Smart and ZigBee) applications

Ultra-low-power (ULP) transceivers enable short-range networks of autonomous sensor nodes for wireless personal-area-network (WPAN) applications. RF PLLs for frequency synthesis and modulation consume a significant share of the total transceiver power, making sub-mW PLLs key to realize ULP WPAN radios. Compared to analog PLLs [1], all-digital PLLs (ADPLLs) are preferred in nanoscale CMOS as they offer benefits of smaller area, programmability, capability of extensive self-calibrations, and easy portability [2]. However, analog PLLs dominate the field of ULP WPAN radios [1], since the time-to-digital-converter (TDC) of an ADPLL has traditionally been power hungry. We present a 2.1-to-2.7GHz 860μW fractional-N ADPLL in 40nm CMOS for WPAN applications, which breaks the 1mW barrier and consumes at least 5× lower power compared to state-of-the-art ADPLLs.

9.5 A 1.2nJ/b 2.4GHz receiver with a sliding-IF phase-to-digital converter for wireless personal/body-area networks

This paper presents an ultra-low power 2.4 GHz FSK/PSK RX for wireless personal/body area networks. A single-channel phase-tracking RX based on a sliding-IF phase-to-digital conversion (SIF-PDC) loop is proposed to directly demodulate and digitize the frequency/phase-modulated information. The sliding-IF frequency plan reduces the power consumption of the multi-phase LO generation. A phase rotator is adopted in SIF-PDC to guarantee frequency stability, i.e., avoid the frequency pulling by interference or frequency drift. It equivalently transforms the RF signal processing from the I/Q amplitude domain to a digital-phase domain, which saves up to nearly 40% on power consumption and relaxes the digital baseband complexity. A phase-domain linear model of the proposed SIF-PDC is presented to analyze the frequency response. Fabricated in a 90 nm CMOS technology, the presented RX consumes 2.4 mW at 2 Mbps data rate, i.e., 1.2 nJ/b efficiency, and achieves a sensitivity of -92 dBm.

13.2 A 3.7mW-RX 4.4mW-TX fully integrated Bluetooth Low-Energy/IEEE802.15.4/proprietary SoC with an ADPLL-based fast frequency offset compensation in 40nm CMOS

This paper presents an ultra-low-power (ULP) fully-integrated Bluetooth Low-Energy(BLE)/IEEE802.15.4/proprietary RF SoC for Internet-of-Things applications. Ubiquitous wireless sensors connected through cellular devices are becoming widely used in everyday life. A ULP RF transceiver is one of the most critical components that enables these emerging applications, as it can consume up to 90% of total battery energy. Furthermore, a low-cost radio design with an area-efficient fully integrated RF SoC is an important catalyst for developing such applications. By employing a low-voltage digital-intensive architecture, the presented SoC is fully compliant with BLE and IEEE802.15.4 PHY/Data-link requirements and achieves state-of-the-art power consumption of 3.7mW for RX and 4.4mW for TX.

A 915 MHz, Ultra-Low Power 2-Tone Transceiver With Enhanced Interference Resilience

An ultra-low-power RF envelope-detection radio has been designed for low-power short-range wireless applications. It introduces an interference rejection technique that improves the in-band selectivity by 24.5 dB. The transmitter adopts the power-efficient direct-modulation architecture, and the receiver maintains the simplicity and low power consumption of envelope detection receivers. In the 915 MHz ISM band at 10 kbps the transmitter output level reaches - 3 dBm with 33.9% global efficiency, while the receiver achieves -83 dBm sensitivity with 121 μW power consumption. The Tx and Rx implemented in 90 nm CMOS technology occupy 0.71 and 1.27 mm2 , respectively.

9.7 A 0.33nJ/b IEEE802.15.6/proprietary-MICS/ISM-band transceiver with scalable data-rate from 11kb/s to 4.5Mb/s for medical applications

The introduction of the IEEE802.15.6 standard (15.6) for wireless-body-area networks signals the advent of new medical applications, where various wireless nodes in, on or around a human body monitor vital signs. Radio communication often dominates the power consumption in the nodes, thus low-power transceivers are desired. Most state-of-the-art low-power transceivers support only proprietary modes with OOK or FSK modulations, and have poor sensitivity or low data rate [1,2]. In this work, a 15.6-compliant transceiver with enhanced performance is proposed. First, the data-rate is extended to 4.5Mb/s to cover multi-channel EEG applications. Second, while a best-in-class energy efficiency of 0.33nJ/b is achieved in the high-speed mode, a dedicated low-power mode reduces the RX power further in low-data-rate operation. Third, a sensitivity 5 to 10dB better than the 15.6 specification is targeted to accommodate extra path loss due to shadowing effects from human bodies.

A 0.33 nJ/bit IEEE802.15.6/Proprietary MICS/ISM Wireless Transceiver With Scalable Data Rate for Medical Implantable Applications

This paper presents an ultra-low power wireless transceiver specialized for but not limited to medical implantable applications. It operates at the 402-405-MHz medical implant communication service band, and also supports the 420-450-MHz industrial, scientific, and medical band. Being IEEE 802.15.6 standard compliant with additional proprietary modes, this highly configurable transceiver achieves date rates from 11 kb/s to 4.5 Mb/s, which covers the requirements of conventional implantable applications. The phase-locked loop-based transmitter architecture is adopted to support various modulation schemes with limited power budget. The zero-IF receiver has programmable gain and bandwidth to accommodate different operation modes. Fabricated in 40-nm CMOS technology with 1-V supply, this transceiver only consumes 1.78 mW for transmission and 1.49 mW for reception. The ultra-low power consumption together with the 15.6-compliant performance in term of modulation accuracy, sensitivity, and interference robustness make this transceiver competent for various implantable applications.

26.3 A 1.3nJ/b IEEE 802.11ah fully digital polar transmitter for IoE applications

This paper presents an ultra-low-power (ULP) IEEE 802.11ah fully-digital polar transmitter (TX). IEEE 802.11ah is a new Wi-Fi protocol optimized for Internet-of-Everything (IoE) applications. Compared to other IoE standards like Bluetooth or ZigBee, its sub-GHz carrier frequency and mandatory modes with 1MHz/2MHz channel bandwidths allow devices to operate in a longer range with scalable data-rates from 150kb/s to 2.1Mb/s. Moreover, the use of OFDM improves link robustness against fading, especially in urban environments, and achieves a higher spectral efficiency. The key design challenges of an IEEE 802.11ah TX for IoE applications are to meet the tight spectral mask and error-vector-magnitude (EVM) requirements as for conventional Wi-Fi standards (e.g., 802.11n/g), while achieving low power consumption required by IoE applications. The presented TX applies a fully-digital polar architecture with a 1V supply, and it achieves more than 10× power reduction compared to the state-of-the-art OFDM transceivers [1-4]. Without any complicated PA pre-distortion techniques as in [5], it passes all the PHY requirements of the mandatory modes in IEEE 802.11ah with 4.4% EVM, while consuming 7.1mW with 0dBm output power.

A 2.4GHz class-D power amplifier with conduction angle calibration for −50dBc harmonic emissions

We present a digitally-controlled class-D power amplifier (PA) utilizing a new conduction angle calibration technique for harmonic suppression. The optimum conduction angle is derived to minimize chosen harmonics. The calibration circuit adjusts the conduction angle by changing the voltage transfer characteristic of the input buffer. Operating at 2.4GHz, this single-ended PA achieves a drain efficiency of 39% with an output power of 1.2dBm from a 1V supply. The even-order harmonics can be suppressed to below -49dBm. Integrated with an RF frequency modulator, the PA fully meets the spectral mask requirements for Bluetooth Smart applications.

A 915MHz 120μW-RX/900μW-TX envelope-detection transceiver with 20dB in-band interference tolerance

Minimizing the power consumption while maintaining performance is paramount in radio transceiver design for low-power wireless sensor network (WSN) applications. Given a sub-mW power budget, many radios have utilized amplitude modulation and envelope detection to eliminate the need for accurate frequency references and to reduce power consumption [1-4]. However, such radios suffer from poor frequency selectivity. They rely on front-end filters to reject out-of-band interference, while in-band interferers still corrupt the desired signal.