This paper presents a low-power SoC that performs EEG acquisition and feature extraction required for continuous detection of seizure onset in epilepsy patients. The SoC corresponds to one EEG channel, and, depending on the patient, up to 18 channels may be worn to detect seizures as part of a chronic treatment system. The SoC integrates an instrumentation amplifier, ADC, and digital processor that streams features-vectors to a central device where seizure detection is performed via a machine-learning classifier. The instrumentation-amplifier uses chopper-stabilization in a topology that achieves high input-impedance and rejects large electrode-offsets while operating at 1 V; the ADC employs power-gating for low energy-per-conversion while using static-biasing for comparator precision; the EEG feature extraction processor employs low-power hardware whose parameters are determined through validation via patient data. The integration of sensing and local processing lowers system power by 14x by reducing the rate of wireless EEG data transmission. Feature vectors are derived at a rate of 0.5 Hz, and the complete one-channel SoC operates from a 1 V supply, consuming 9 J per feature vector.Index Terms-1/f noise, algorithm design and analysis, amplifiers, biomedical equipment, brain, choppers, digital signal processing, electroencephalography, low-noise amplifiers, low-power electronics.

A 350µW MSK direct modulation transmitter and a 400µW OOK super-regenerative receiver (SRR) are implemented in 90nm CMOS technology. The transceiver tunes 24MHz in frequency steps smaller than 2kHz and is designed to meet the specifications of the Medical Implant Communications Service (MICS) standard in the 402-405MHz band. The transmitter meets MICS mask specifications with data rates up to 120kbps, and the receiver has a sensitivity better than -99dBm with a data rate of 40kbps or -93dBm with a data rate of 120kbps.

Recent advances in the medical field are spurring the need for ultra-low power transceivers for wireless communication with medical implants. To deal with the growing demand for medical telemetry, the FCC commissioned the Medical Implant Communications Services (MICS) standard in 1999 in the 402-405 MHz band. This paper presents a 350 W FSK/MSK direct modulation transmitter and a 400 W OOK super-regenerative receiver (SRR) specifically optimized for medical implant communications. The transceiver is implemented in 90 nm CMOS and digitally tunes 24 MHz in frequency steps smaller than 2 kHz. The transmitter meets MICS mask specifications with data rates up to 120 kb/s consuming only 2.9 nJ/bit; the receiver has a sensitivity better than 99 dBm with a data rate of 40 kb/s or 93 dBm with a data rate of 120 kb/s consuming 3.3 nJ/bit. A frequency correction loop incorporating the base-station is prototyped to eliminate the need for a frequency synthesizer in the implant while still achieving frequency stability of less than 3 ppm.

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We describe a new outphasing energy recovery amplifier (OPERA) which replaces the isolation resistor in the conventional matched combiner with a resistance-compressed rectifier for improved efficiency. The rectifier recovers the power normally wasted in the isolation resistor back to the power supply, while a resistance compression network (RCN) reduces the impedance variation of the rectifier as the output power varies. Because the combiner requires a fixed resistance at the isolation port to ensure matching and isolation between the two outphased power amplifiers (PAs), the RCN serves to maintain high linearity as well as high efficiency in the switching-mode PAs. For demonstration, a prototype OPERA system is designed and implemented with discrete components at an operating frequency of 48 MHz, delivering 20.8 W peak power with 82.9% PAE. The measurement results show an efficiency improvement from 17.9% to 42.0% for a 50-kHz 16-QAM signal with a peak-to-average power ratio of 6.5 dB.

Since its invention in 1922, the super-regenerative amplifier (SRA) has been used in a variety of short-range, low-power, and/or low-cost wireless systems due to its simple implementation and excellent performance for a given power budget. Growing demand for ultralow-power receivers for short-range radios has recently reawakened an interest in the theory and design of SRAs. Building on recent work and using reasonable assumptions and approximations, we present a frequency-domain model for analyzing SRAs. We then use these models to predict the response of an SRA to arbitrary deterministic and stochastic signals including sinusoids, pulsed-sinusoids, and additive white Gaussian noise. Using the results, we present formulas for calculating the sensitivity and selectivity of SRAs. We also introduce the concept of a trigger-time that is particularly useful for accurately determining the optimal threshold in on-off keying (OOK) receivers and helps avoid the problems introduced by nonlinearity in SRAs. Finally, we present a prototype OOK SRA that achieves a sensitivity of 90 dBm at a bit rate of 300 kbps (BER of 10 3 ) while consuming 500 W, and show that its measured sensitivity matches theory within 1 dB.Index Terms-Super-regenerative amplifier (SRA), super-regenerative receiver, low power, oscillators, short-range radio.

Abstract-This paper presents a 2.14-GHz, four-way power combining and outphasing system for high-power amplifiers such as those in radio basestations (RBS). The combiner is ideally lossless, and enables power control through load modulation of the power amplifiers (PAs). A discrete-component power combiner is designed and characterized, and combined with inverse Class-F PAs using GaN HEMT devices to develop a complete PA system. We demonstrate the effectiveness of the system over a range of outphasing control angles. This first-ever microwave implementation of the outphasing system has a peak CW drain efficiency of 68.9%, with efficiency greater than 55% over a 5.5-dB power range. It provides an average modulated efficiency of 57% for a W-CDMA signal with 3.47-dB peak to average power ratio (PAPR) at 42-dBm output power.Index Terms-base stations, outphasing, power amplifier (PA)