Jianxun Zhu

Prototyping energy harvesting active networked tags (EnHANTs)

This paper focuses on a new type of wireless devices in the domain between RFIDs and sensor networks - Energy Harvesting Active Networked Tags (EnHANTs). Future EnHANTs will be small, flexible, and self-powered devices that can be attached to objects that are traditionally not networked (e.g., books, toys, clothing), thereby providing the infrastructure for novel tracking applications. We present the design considerations for the EnHANT prototypes, developed over the past 3 years. The prototypes harvest indoor light energy using custom organic solar cells, communicate and form multihop networks using ultralow-power Ultra-Wideband Impulse Radio (UWB-IR) transceivers, and adapt their communications and networking patterns to the energy harvesting and battery states. We also describe a small scale EnHANTs testbed that uniquely allows evaluating different algorithms with trace-based light energy inputs.

Energy-Harvesting Active Networked Tags (EnHANTs): Prototyping and Experimentation

This article focuses on a new type of wireless devices in the domain between RFIDs and sensor networks—Energy-Harvesting Active Networked Tags (EnHANTs). Future EnHANTs will be small, flexible, and self-powered devices that can be attached to objects that are traditionally not networked (e.g., books, furniture, toys, produce, and clothing). Therefore, they will provide the infrastructure for various tracking applications and can serve as one of the enablers for the Internet of Things. We present the design considerations for the EnHANT prototypes, developed over the past 4 years. The prototypes harvest indoor light energy using custom organic solar cells, communicate and form multihop networks using ultra-low-power Ultra-Wideband Impulse Radio (UWB-IR) transceivers, and dynamically adapt their communications and networking patterns to the energy harvesting and battery states. We describe a small-scale testbed that uniquely allows evaluating different algorithms with trace-based light energy inputs. Then, we experimentally evaluate the performance of different energy-harvesting adaptive policies with organic solar cells and UWB-IR transceivers. Finally, we discuss the lessons learned during the prototype and testbed design process.

Field-Programmable LNAs With Interferer-Reflecting Loop for Input Linearity Enhancement

A field-programmable (FP) low-noise amplifier (LNA) with interferer-reflecting (IR) loop is introduced. The user can program its gain, noise figure, linearity and power consumption during operation. The IR loop uses a frequency-selective shunt-shunt feedback around the noise-canceling LNA to reduce the input impedance out of band and to suppress the input voltage swing created by blockers. A notch filter at the desired operation frequency in the feedback path results in selectivity at the RF input so that all out-of-band blockers are suppressed without the need to know blocker locations and the LNA input linearity is improved. 65 nm CMOS chip prototypes have been implemented with on-chip LC, bondwire LC or N-path notch filters. The FP N-path IR-LNA operates from 0.2 to 1.6 GHz; with the IR disabled, the NF is 2.4 dB, B1 dB is -15 dBm, and the OOB-IIP3 is +2.5 dBm with a 13 mW power consumption; with the IR on, the NF is 3.6 dB, the RF channel input bandwidth is 20 MHz, the B1 dB is -4 dBm and the OOB-IIP3 is +14.5 dBm. The LNA has an analog VDD of 1.6 V and an LO VDD of 1 V and dissipates 15.8 to 20.2 mW across operating frequencies.

Demo: prototyping UWB-enabled enhants

Energy Harvesting Active Networked Tags (EnHANTs) are a new class of devices in the domain between RFIDs and sensor networks. EnHANTs will be small, flexible, and energetically self-reliant. Their development is enabled by advances in ultra-low-power ultra-wideband (UWB) communications and in organic semiconductor-based energy harvesting materials. In this demo, we present UWB-enabled EnHANT prototypes. Each prototype is based on a MICA2 mote integrated with a UWB Transceiver and an energy harvesting module (EHM) that allows demonstrating energy harvesting-adaptive communications. Additional information about EnHANTs is available at [2] and http://enhants.ee.columbia.edu.

Demo: Organic solar cell-equipped energy harvesting active networked tag (EnHANT) prototypes

Energy Harvesting Active Networked Tags (EnHANTs) will be a new class of devices in the domain between RFIDs and sensor networks. Small, flexible, and energetically self-reliant, EnHANTs will be attached to objects that are traditionally not networked, such as books, furniture, toys, produce, and clothing. More information about the EnHANTs project is available at http://enhants.ee.columbia.edu. In this demo we present a small network of EnHANT prototypes. The current EnHANT prototypes are integrated with novel custom in-house-developed energy harvesting and communications hardware, namely organic solar cells and ultra-wide-band impulse radio (UWB-IR) transceivers. The demo showcases prototypes communicating using the novel UWB-IR transceivers and adapting their communications and networking parameters to the available environmental energy harvested by the organic solar cells.

A DC-9.5GHz noise-canceling distributed LNA in 65nm CMOS

Summary form only given. A low noise amplifier is presented that uniquely achieves wide-band input matching and good low-frequency noise performance at the same time. Its topology is a hybrid of distributed amplifier and a common-source common-gate noise-canceling amplifier. The proof-of-principle prototype in 65nm CMOS operates from DC up to 9.5GHz with more than 12dB gain, achieves a minimum noise figure of 2.8dB, P1dB of -7dBm, IIP3 of +4dBm, consumes 18mW from a 1.4V power supply and occupies a total active area of 0.4mm2.

Frequency-Translational Quadrature-Hybrid Receivers for Very-Low-Noise, Frequency-Agile, Scalable Inter-Band Carrier Aggregation

A frequency-translational quadrature-hybrid receiver is proposed that achieves wideband input matching for a reflective low-noise-amplifier input impedance and enables the realization of wideband, concurrent receivers. Frequency-agile, inter-band carrier aggregation is realized from a single antenna through RF signal sharing and quadrature-hybrid-coupler daisy chaining. A 1.1 V 65 nm CMOS prototype chip is demonstrated that has a sub-1 dB minimum NF, a 12 MHz to 70 MHz RF bandwidth, a +8 dBm II P3, and a -15 dBm B1dB and consumes <;58 mW per channel. The prototypes have been integrated into a demonstration system that features 4-band inter-band carrier aggregation with modulated carriers placed between 0.69 and 2.1 GHz and received with an EVM <;2.8%.

A field-programmable noise-canceling wideband receiver with high-linearity hybrid class-AB-C LNTAs

A field-programmable noise-canceling wide-band receiver front end with high performance LNTAs is presented. The common-source (CS) and common-gate (CG) LNTAs are split into several cells whose bias point can be individually programmed in class AB or C yielding a highly linear hybrid class-AB-C LNTA. The 40nm LP CMOS receiver prototype can be programmed on the fly to adapt to different RF environments; it was tested in a low noise mode, a high linearity mode and a low power mode. Across these modes, the receiver has maximum gain of 53dB, a minimum NF of 2.2dB, a maximum B1 dB of +11dBm, and a maximum OB-IIP3 of +21dBm; the signal path consumes between 15 and 40mA from a 2.5V supply and the LO current varies from 2.2 to 20mA from a 1.1V supply across operating frequencies. The measured LO emission at the antenna port is <;-84dBm.

A Direct RF-to-Information Converter for reception and wideband interferer detection employing pseudo-random LO modulation

The Direct RF-to-Information Converter (DRF2IC) unifies high sensitivity signal reception, narrowband spectrum sensing and energy-efficient wideband interferer detection into a fast-reconfigurable and easily scalable architecture. In reception mode, the DRF2IC RF front-end (RFFE) consumes 46.5mW and delivers 40MHz RF bandwidth, 41.5dB conversion gain, 3.6dB NF and −2dBm B1dB. 72dB out-of-channel blocker rejection is achieved in narrowband sensing mode. In compressed sensing wideband interferer detection mode, 66dB operational dynamic range, 40dB instantaneous dynamic range, 1.43GHz instantaneous bandwidth (IBW) is demonstrated and 6 interferers scattered over 1.26GHz are detected in 1.2uS consuming 58.5mW.

RF circuit and system innovations for a new generation of wireless terminals

Next-generation (Next-G) wireless terminals need to sense their ambient and adapt to the diverse deployment scenario requirements on the fly while leveraging technology scaling. Several key circuit and system innovations are required to make the realization of this vision possible. We discuss how compressed sampling can be exploited to design a rapid, GHz-wide and energy-efficient interferer detector using a quadrature analog-to-information converter. A family of field-programmable receiver front ends demonstrating two linearity enhancement techniques including interferer-reflecting loops and hybrid Class-AB-C low noise transconductors is discussed. The technology scalable and out-of-band blocker robust switched-capacitor RF front end is then presented.