Haowei Jiang

24.5 A 4.5nW wake-up radio with −69dBm sensitivity

Wake-up receivers (WuRXs) are low-power radios that continuously monitor the RF environment to wake up a higher-power radio upon detection of a predetermined RF signature. Prior-art WuRXs have 100s of kHz of bandwidth [1] with low signature-to-wake-up-signal latency to help synchronize communication amongst nominally asynchronous wireless devices. However, applications such as unattended ground sensors and smart home appliances wake-up infrequently in an event-driven manner, and thus WuRX bandwidth and latency are less critical; instead, the most important metrics are power consumption and sensitivity. Unfortunately, current state-of-the-art WuRXs utilizing direct envelope-detecting [2] and IF/uncertain-IF [1,3] architectures (Fig. 24.5.1) achieve only modest sensitivity at low-power (e.g., −39dBm at 104nW [2]), or achieve excellent sensitivity at higher-power (e.g., −97dBm at 99µW [3]) via active IF gain elements. Neither approach meets the needs of next-generation event-driven sensing networks.

An Audio Jack-Based Electrochemical Impedance Spectroscopy Sensor for Point-of-Care Diagnostics

Portable and easy-to-use point-of-care (POC) diagnostic devices hold high promise for dramatically improving public health and wellness. In this paper, we present a mobile health immunoassay platform based on audio jack-embedded devices, such as smartphones and laptops, that uses electrochemical impedance spectroscopy to detect binding of target biomolecules. This platform is intended to be used as a plug-and-play peripheral that reuses existing hardware in the mobile device, and does not require an external battery, thereby improving upon its convenience and portability. Experimental data using a passive circuit network to mimic an electrochemical cell demonstrate that the device performs comparable to laboratory grade instrumentation with 0.3% and 0.5° magnitude and phase error, respectively, over a 17 Hz–17 kHz frequency range. The measured power consumption is 2.5 mW with a dynamic range of 60 dB. This platform was verified by monitoring the real-time formation of a NeutrAvidin self-assembled monolayer on a gold electrode demonstrating the potential for POC diagnostics.

A hybrid semi-digital transimpedance amplifier for nanopore-based DNA sequencing.

Over the past two decades, nanopores have been a promising technology for next generation deoxyribonucleic acid (DNA) sequencing. As single-stranded DNA translocates through a nanopore, each nucleotide induces a blockage in the ionic channel, creating a unique current signature. However, the fast translocation speed and small current changes, which are superimposed on a much larger baseline current, pose significant technical challenges on the measurement circuitry. Furthermore, the rapid change in the baseline current that occurs during translocation necessitates the step response of the measurement circuitry be minimized. Here we present a hybrid semi-digital transimpedance amplifier to sense these minute current signatures while discharging the baseline current using a semidigital feedback loop. The amplifier achieves fast settling by adaptively altering the bandwidth of the feedback loop when a step input is detected. Measurement results show the performance of the amplifier with 100 MΩ DC gain, 560 kHz flat-gain bandwidth, and 5 fA/√Hz input-referred current noise. The fast settling response is demonstrated by observing the insertion of a protein nanopore in a lipid bilayer.

A Hybrid Semi-Digital Transimpedance Amplifier With Noise Cancellation Technique for Nanopore-Based DNA Sequencing

Over the past two decades, nanopores have been a promising technology for next generation deoxyribonucleic acid (DNA) sequencing. Here, we present a hybrid semi-digital transimpedance amplifier (HSD-TIA) to sense the minute current signatures introduced by single-stranded DNA (ssDNA) translocating through a nanopore, while discharging the baseline current using a semi-digital feedback loop. The amplifier achieves fast settling by adaptively tuning a DC compensation current when a step input is detected. A noise cancellation technique reduces the total input-referred current noise caused by the parasitic input capacitance. Measurement results show the performance of the amplifier with 31.6 M Ω mid-band gain, 950 kHz bandwidth, and 8.5 fA/ √Hz input-referred current noise, a 2× noise reduction due to the noise cancellation technique. The settling response is demonstrated by observing the insertion of a protein nanopore in a lipid bilayer. Using the nanopore, the HSD-TIA was able to measure ssDNA translocation events.

A 400 MHz 4.5 nW −63.8 dBm sensitivity wake-up receiver employing an active pseudo-balun envelope detector

A 402–405 MHz MICS-band wake-up receiver is presented that achieves −63.8 dBm sensitivity at 4.5 nW. High sensitivity at 400 MHz is accomplished via an 18.5 dB passive voltage gain transformer filter loaded by a high input impedance (Rin > 30 kΩ), high scaling factor (kED > 300), 1.8 nW current re-use pseudo-balun envelope detector, while low power is achieved by operating all active circuits, including the re-generative comparator, baseband correlator, and temperature compensated relaxation oscillator in sub-threshold with a single 0.4 V supply. The chip is fabricated using 0.18 μm CMOS SOI process and achieves the highest figure of merit of all direct envelope detection-based wake-up receivers operating above 400 MHz.