Fabrication and analysis of 2x2 thermo-optic SOI waveguide switch with low power consumption and fast response by anisotropy chemical etching

A low power consumption 2 x 2 thermo-optic switch with fast response was fabricated on silicon-on-insulator by anisotropy chemical etching. Blocking trenches were etched on both sides of the phase-shifting arms to shorten device length and reduce power consumption. Thin top cladding layer was grown to reduce power consumption and switching time. The device showed good characteristics, including a low switching power of 145 mW and a fast switching speed of 8 +/- 1 mus, respectively. Two-dimensional finite element method was applied to simulate temperature field in the phase-shifting arm instead of conventional one-dimensional method. According to the simulated result, a new two-dimensional index distribution of phase-shifting arm was determined. Consequently finite-difference beam propagation method was employed to simulate the light propagation in the switch, and calculate the power consumption as well as the switching speed. The experimental results were in good agreement with the theoretical estimations. (C) 2004 Elsevier B.V. All rights reserved.

A novel ultra low power temperature sensor for UHF RFID tag chip

A novel ultra low power temperature sensor for UHF RFID tag chip is presented. The sensor consists of a constant pulse generator, a temperature related oscillator, a counter and a bias. Conversion of temperature to digital output is fulfilled by counting the number of the clocks of the temperature related oscillator in a constant pulse period. The sensor uses time domain comparing, where high power consumption bandgap voltage references and traditional ADCs are not needed. The sensor is realized in a standard 0.18 mu m CMOS process, and the area is only 0.2mm(2). The accuracy of the temperature sensor is +/- 1 degrees C after calibration. The power consumption of the sensor is only 0.9 mu W.

A Low Power Baseband Chain for CMMB Application

This paper presents experimental results of an analog baseband circuit for China Multimedia Mobile Broadcasting (CMMB) direct conversion receiver in 0.35um SiGe BiCMOS process. It is the first baseband of CMMB RFIC reported so far. A 8(th)-order chebyshev low pass filter (LPF) with calibration system is used in the analog baseband circuit, the filter provides 0.5 dB passband ripple and -35 dB attenuation at 6MHz with the cutoff frequency at 4MHz, the calibration of filter is reported to achieve the bandwidth accuracy of 3%. The baseband variable gain amplifier (VGA) achieves more than 40 dB gain tuning with temperature compensation. In addition, A DC offset cancellation circuit is also introduced to remove the offset from layout and self-mixing, and the remaining offset voltage and current consumption are only 6mV and 412uA respectively. Implemented in a 0.35um SiGe technology with 1.1 mm(2) die size, this tuner baseband achieves OIP3 of 25.5 dBm and dissipate 16.4 mA under 2.8-V supply.

Low Power Integrated Circuits for Wireless Neural Recording Applications

A group of prototype integrated circuits are presented for a wireless neural recording micro-system. An inductive link was built for transcutaneous wireless power transfer and data transmission. Power and data were transmitted by a pair of coils on a same carrier frequency. The integrated receiver circuitry was composed of a full-wave bridge rectifier, a voltage regulator, a date recovery circuit, a clock recovery circuit and a power detector. The amplifiers were designed with a limited bandwidth for neural signals acquisition. An integrated FM transmitter was used to transmit the extracted neural signals to external equipments. 16.5 mW power and 50 bps - 2.5 Kbps command data can be received over 1 MHz carrier within 10 mm. The total gain of 60 dB was obtained by the preamplifier and a main amplifier at 0.95Hz - 13.41 KHz with 0.215 mW power dissipation. The power consumption of the 100 MHz ASK transmitter is 0.374 mW. All the integrated circuits operated under a 3.3 V power supply except the voltage regulator.

Design of Low Power Multi-Standard Active-RC Filter for WLAN and DVB-H

In this paper, a low-power, highly linear, integrated, active-RC filter exhibiting a multi-standard (IEEE 802.11a/b/g and DVB-H) application and bandwidth (3MHz, 4MHz, 9.5MHz) is present. The filter exploits digitally-controlled polysilicon resister banks and an accurate automatic tuning scheme to account for process and temperature variations. The automatic frequency calibration scheme provides better than 3% corner frequency accuracy. The Butterworth filter is design for receiver (WLAN and DVB-H mode) and transmitter (WLAN mode). The filter dissipation is 3.4 mA in RX mode and 2.3 mA (only for one path) in TX mode from 2.85-V supply. The dissipation of calibration consumes 2mA. The circuit has been fabricated in a 0.35um 47-GHz SiGe BiCMOS technology, the receiver and transmitter occupy 0.28-mm(2) and 0.16-mm(2) (calibration circuit excluded), respectively.

A Novel Low-Power Digital Baseband Circuit for UHF RFID Tag with Sensors

A novel low-power digital baseband circuit for UHF RFID tag with sensors is presented in this paper. It proposes a novel baseband architecture and a new operating scheme to fulfill the sensor functions and to reduce power consumption. It is also compatible with the EPC C1G2 UHF RFID protocol. It adopts some advanced low power techniques for system design and circuit design: adaptive clock-gating, multi-clock domain and asynchronous circuit. The baseband circuit is implemented in 0.18um 1P3M standard CMOS process. ne chip area is 0.28 mm(2) excluding test pads. Its power consumption is 25uW under 1.1V power supply.

An Embedded Ultra Low Power Nonvolatile Memory in a Standard CMOS Logic Process

This paper proposes an embedded ultra low power nonvolatile memory in a standard CMOS logic process. The memory adopts a bit cell based on the differential floating gate PMOS structure and a novel operating scheme. It can greatly improve the endurance and retention characteristic and make the area/bit smaller. A new high efficiency all-PMOS charge pump is designed to reduce the power consumption and to increase the power efficiency. It eliminates the body effect and can generate higher output voltage than conventional structures for a same stage number. A 32-bit prototype chip is fabricated in a 0.18 mu m 1P4M standard CMOS logic process and the core area is 0.06 mm(2). The measured results indicate that the typical write/erase time is 10ms. With a 700 kHz clock frequency, power consumption of the whole memory is 2.3 mu A for program and 1.2 mu A for read at a 1.6V power supply.

A 5GHz low power WLAN transceiver SiGe RFIC for personal communication terminal applications

A low-cost low-power single chip WLAN 802.11a transceiver is designed for personal communication terminal and local multimedia data transmission. It has less than 130mA current dissipation, maximal 67dB gain and can be programmed to be 20dB minimal gain. The receiver system noise figure is 6.4dB in hige-gain mode.

A low power integrated CMOS transmitter for BCI system

The prototype wafer of a low power integrated CMOS Transmitter for short-range biotelemetry application has been designed and fabricated, which is prospective to be implanted in the human brain to transfer the extracted neural information to the external computer. The transmitter consists of five parts, a bandgap current regulator, a ring oscillator, a buffer, a modulator and a power transistor. High integration and low power are the most distinct criteria for such an implantable integrated circuit. The post-simulation results show that under a 3.3 V power supply the transmitter provides 100.1 MHz half-wave sinusoid current signal to drive the off-chip antenna, the output peak current range is -0.155 mA similar to 1.250 mA, and on-chip static power dissipation is low to 0.374 mW. All the performances of the transmitter satisfy the demands of wireless real-time BCI system for neural signals recording and processing.

A low power consumption thermo-optic variable optical attenuator based on SOI material

A SOI thenno-optic variable optical attenuator with U-grooves based on a multimode interference coupler principle is fabricated. The dynamic attenuation range is 0 to 29 dB; at the wavelength range between 1510 nm and 1610nm, and the maximum power consumption is only l30mW. Compared to the variable optical attenuator without U-groove, the maximum power consumption decreases more than 230mW

A novel low-power input-independent MOS AC/DC charge pump

This paper presents a novel fully integrated MOS AC to DC charge pump with low power dissipation and stable output for RFID applications. To improve the input sensitivity, we replaced Schottky-diodes in conventional charge pumps with MOS diodes with zero threshold, which has less process defects and is thus more compatible with other circuits. The charge pump in a RFID transponder is implemented in a 0.35um CMOS technology with 0.24 sq mm die size. The analytical model of the charge pump and the simulation results are presented.

An Ultra Low Power Non-volatile Memory in Standard CMOS Process for Passive RFID Tags

An ultra low power non-volatile memory is designed in a standard CMOS process for passive RFID tags. The memory can operate in a new low power operating scheme under a wide supply voltage and clock frequency range. In the charge pump circuit the threshold voltage effect of the switch transistor is almost eliminated and the pumping efficiency of the circuit is improved. An ultra low power 192-bit memory with a register array is implemented in a 0.18 mu M standard CMOS process. The measured results indicate that, for the supply voltage of 1.2 volts and the clock frequency of 780KHz, the current consumption of the memory is 1.8 mu A (3.6 mu A) at the read (write) rate of 1.3Mb/s (0.8Kb/s).

Laser irradiation cell photothermal therapy assisted by gold nanoparticles

The strong absorption of gold nanoparticles in the visible spectral range allows the localized generation of heat in a volume of only a few tens of nanometer. The efficient conversion of strongly absorbed light by plasmonic gold nanoparticles to heat energy and their easy bioconjugation suggest that the gold nanoparticles can be used as selective photothermal agents in molecular cell targeting. The selective destruction of alkaline phosphatase, the permeabilization of the cell membrane and the selective killing of cells by laser irradiating gold nanoparticles were demonstrated. The potential of using this selective technique in molecularly targeted photothermal therapy and transfection is discussed.

Color center conversion by femtosecond pulse laser irradiation in LiF : F-2 crystals

We report the observation of intense spontaneous emission of green light from LiF:F-2:F-3(+) centers in active channel waveguides generated in lithium fluoride crystals by near-infrared femtosecond laser radiation. While irradiating the crystal at room temperature with 405 nm light from a laser diode, yellow and green emission was seen by the naked eye. Stripe waveguides were fabricated by translating the crystal along the irradiated laser pulse, and their guiding properties and fluorescence spectra at 540 nm demonstrated. This single-step process inducing a waveguide structure offers a good prospect for the development of a waveguide laser in bulk LiF crystals.