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Phillip E. Allen

Bio: Phillip E. Allen is an academic researcher. The author has contributed to research in topics: Ring oscillator & Vackář oscillator. The author has an hindex of 1, co-authored 1 publications receiving 197 citations.

Papers
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01 Jan 2006
TL;DR: In this article, the design and characterization of a process, temperature and supply compensation technique for a 7-MHz clock oscillator in a 0.25-m, two-poly five-metal (2P5M) CMOS process is described.
Abstract: This paper reports on the design and characterization of a process, temperature and supply compensation technique for a 7-MHz clock oscillator in a 0.25- m, two-poly five-metal (2P5M) CMOS process. Measurements made across a temperature range of 40 C to 125 C and 94 samples collected over four fabrica- tion runs indicate a worst case combined variation of 2.6% (with process, temperature and supply). No trimming was performed on any of these samples. The oscillation frequencies of 95% of the sam- ples were found to fall within 0.5% of the mean frequency and the standard deviation was 9.3 kHz. The variation of frequency with power supply was 0.31% for a supply voltage range of 2.4-2.75 V. The clock generator is based on a three-stage differential ring oscillator. The variation of the frequency of the oscillator with tem- perature and process has been discussed and an adaptive biasing scheme incorporating a unique combination of a process corner sensing scheme and a temperature compensating network is de- veloped. The biasing circuit changes the control voltage of the dif- ferential ring oscillator to maintain a constant frequency. A com- parator included at the output stage ensures rail-to-rail swing. The oscillator is intended to serve as a start-up clock for micro-con- troller applications.

197 citations


Cited by
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Journal ArticleDOI
TL;DR: A long-range UHF RF identification (RFID) sensor has been designed using a 0.35- ¿m CMOS standard process that allows the use of the RFID as a batteryless sensor in a wireless human body temperature monitoring system.
Abstract: A long-range UHF RF identification (RFID) sensor has been designed using a 0.35- ?m CMOS standard process. The power-optimized tag, combined with the ultralow-power temperature sensor, allows an ID and a temperature reading range of 2 m from a 2-W effective radiated power output power reader. The temperature sensor is based on a ring oscillator, where the temperature dependence of the oscillation frequency is used for thermal sensing. The temperature sensor exhibits a resolution of 0.035°C and an inaccuracy value lower than 0.1°C in the range from 35°C to 45°C after two-point calibration. The average power consumption of the temperature sensor is only 110 nW at ten conversions per second while keeping a high resolution and accuracy. These properties allow the use of the RFID as a batteryless sensor in a wireless human body temperature monitoring system.

220 citations

Journal ArticleDOI
TL;DR: An on-chip CMOS relaxation oscillator with voltage averaging feedback using a reference proportional to supply voltage is presented and achieves 7x reduction in accumulated jitter (at 1500th cycle) as compared to a oscillator without VAF.
Abstract: An on-chip CMOS relaxation oscillator with voltage averaging feedback using a reference proportional to supply voltage is presented. A voltage-averaging feedback (VAF) concept is proposed to overcome conventional relaxation oscillator problems such as sensitivity to comparator delay, aging, and flicker noise of current sources. A test-chip with typical frequency of 14.0 MHz was fabricated in a 0.18 μm standard CMOS process and measured frequency variations of ±0.16 % for supply changes from 1.7 to 1.9 V and ±0.19% for temperature changes from -40 to 125°C. The prototype draws 25 μA from a 1.8 V supply, occupies 0.04 mm2, and achieves 7x reduction in accumulated jitter (at 1500th cycle) as compared to a oscillator without VAF.

179 citations

Journal ArticleDOI
04 Oct 2010
TL;DR: This paper presents a system-on-chip passive RFID tag with an embedded temperature sensor for the EPC Gen-2 protocol in the 900-MHz UHF frequency band and proposes a dual-path clock generator to support both applications with either very accurate link frequency or very low power consumption.
Abstract: This paper presents a system-on-chip passive RFID tag with an embedded temperature sensor for the EPC Gen-2 protocol in the 900-MHz UHF frequency band. A dual-path clock generator is proposed to support both applications with either very accurate link frequency or very low power consumption. On-chip temperature sensing is accomplished with a time-readout scheme to reduce the power consumption. Moreover, a gain-compensation technique is proposed to reduce the temperature sensing error due to process variations by using the same bandgap reference of the tag to generate bias currents for both the current-to-digital converter and the clock generator of the sensor. Also integrated is a 128-bit one-time-programmable (OTP) memory array based on gate-oxide antifuse without extra mask steps. Fabricated in a standard 0.18- μm CMOS process with analog options, the 1.1-mm2 tag chip is bonded onto an antenna using flip-chip technology to realize a complete tag inlay, which is successfully demonstrated and evaluated in real-time wireless communications with commercial RFID readers. The tag inlay achieves a sensitivity of -6 dBm and a sensing inaccuracy of ±0.8° C (3 σ inaccuracy) over operating temperature range from -20°C to 30°C with one-point calibration.

172 citations

Journal ArticleDOI
TL;DR: The design of a 100 kHz frequency reference based on the electron mobility in a MOS transistor is presented, making it suitable for application in wireless sensor networks (WSN) and less than 1.1% over the temperature range from -22degC to 85degC.
Abstract: The design of a 100 kHz frequency reference based on the electron mobility in a MOS transistor is presented. The proposed low-voltage low-power circuit requires no off-chip components, making it suitable for application in wireless sensor networks (WSN). After a single-point calibration, the spread of its output frequency is less than 1.1% (3sigma) over the temperature range from -22degC to 85degC . Fabricated in a baseline 65 nm CMOS technology, the frequency reference circuit occupies 0.11 mm2 and draws 34 muA from a 1.2 V supply at room temperature.

90 citations

Journal ArticleDOI
TL;DR: A fully-integrated 18.5 kHz RC time-constant-based oscillator is designed in 65 nm CMOS for sleep-mode timers in wireless sensors and provides timing noise suppression, leading to 10× reduction in long-term Allan deviation.
Abstract: A fully-integrated 18.5 kHz RC time-constant-based oscillator is designed in 65 nm CMOS for sleep-mode timers in wireless sensors. A comparator offset cancellation scheme achieves $4\times $ to $25\times $ temperature stability improvement, leading to an accuracy of ±0.18% to ±0.55% over −40 to 90 °C. Sub-threshold operation and low-swing oscillations result in ultra-low power consumption of 130 nW. The architecture also provides timing noise suppression, leading to $10\times $ reduction in long-term Allan deviation. It is measured to have a stability of 20 ppm or better for measurement intervals over 0.5 s. The oscillator also has a fast startup-time, with the period settling in 4 cycles.

84 citations