Sheng Xie

Locatable-body temperature monitoring based on semi-active UHF RFID tags.

This paper presents the use of radio-frequency identification (RFID) technology for the real-time remote monitoring of body temperature, while an associated program can determine the location of the body carrying the respective sensor. The RFID chips internal integrated temperature sensor is used for both the human-body temperature detection and as a measurement device, while using radio-frequency communication to broadcast the temperature information. The adopted RFID location technology makes use of reference tags together with a nearest neighbor localization algorithm and a multiple-antenna time-division multiplexing location system. A graphical user interface (GUI) was developed for collecting temperature and location data for the data fusion by using RFID protocols. With a puppy as test object, temperature detection and localization experiments were carried out. The measured results show that the applied method, when using a mercury thermometer for comparison in terms of measuring the temperature of the dog, has a good consistency, with an average temperature error of 0.283 °C. When using the associated program over the area of 12.25 m2, the average location error is of 0.461 m, which verifies the feasibility of the sensor-carrier location by using the proposed program.

Monostable–Bistable Transition Logic Element Formed by Tunneling Real-Space Transfer Transistors With Negative Differential Resistance

We demonstrate three-terminal λ-type negative differential resistance (NDR) tunneling real-space transfer transistors (TRSTT) with InGaAs and a δ-doped GaAs dual-channel structure on a (100) GaAs substrate. The NDR mechanism is attributed to the electron tunneling transfer from a high-mobility InGaAs channel to a low-mobility δ-doped GaAs channel, as well as to a gate electrode through a Schottky cap layer. The maximum of the peak-to-valley current ratio and the transconductance of the peak current density (<i>g</i>_m = Δ<i>J</i>_P/Δ<i>V</i>_GS) reach 3.3 and 72 mS/mm, respectively. The invert operation of MOBILE is realized by employing two TRSTTs connected in series at room temperature.

A design methodology to extend bandwidth for regulated cascode transimpedance amplifier

This brief analyzes the performance of regulated cascode (RGC) topology and develops a broadband transimpedance amplifier (TIA) incorporated with a novel dual shunt-feedback configuration. Compared to traditional RGC circuit, the proposed TIA improves the natural frequency and optimizes the damping factor. Furthermore, the common source auxiliary amplifier is replaced by an inverter amplifier to provide extra gain and reduce the equivalent input noise current. Based on 0.18-μm CMOS technology, a TIA with enhanced RGC structure was optimized and implemented, and the fabricated chip was mounted on a Rogers 4003C printed circuit board. The experimental results demonstrate a 5.2GHz bandwidth and a 60.5 dBΩ transimpedance gain for 0.5 pF photodetector capacitance. The fluctuation of group delay is less than 50 ps, and the measured average equivalent input noise current density is about 14.99 pA/√Hz. The chip consumes 28.4mW using 1.8V supply.

A single-to-differential broadband transimpedance amplifier for 12.5 Gb/s optical links

A broadband transimpedance amplifier (TIA) is designed and analyzed based on Regulated Cascode (RGC) configuration with L-matching network and cascode amplifier. A novel single-to-differential amplifier is also designed to simplify the following limiting amplifier (LA) design and increase the immunity of common-mode noise. The TIA is implemented in UMC 0.18 μm standard CMOS process. The measured transimpedance gain is 57 dBΩ with a −3 dB bandwidth of 8.1GHz. The average equivalent input noise current spectral density is 29 pA/√Hz. The chip consumes 68mW DC power under 1.8V and occupies the area of 0.9mm2.

A Fully Integrated 2.45G Semi-Active RFID Tag IC

In recent years, radio frequency identification (RFID) microwave technology receives great attention because of its advantages, e.g. long identification distance, small size of antenna, high identification speed and strong anti-collision ability. RFID tag plays one of the most important roles in logistics, and therefore special attention should be paid to tag design. In this paper, we present a 2.45G semi-active tag design, which is compatible with ISO 18000-4. The proposed tag can switch the manners of working between active and passive. When the generated RF-power is sufficient to operate, the tag works as a passive tag, and low noise amplifier (LNA), oscillator (OSC) and power amplifier (PA) are cut off to save the whole chip power consumption mostly. Otherwise it operates in active mode using battery power, and the working distance is greatly increased as a result of using PA.

The study on nonlinear bifurcation dynamics of a semiconductor ring laser

Based on dynamics models of the electronic bi-stable behavior in a semiconductor ring laser and using the methods of the modern nonlinear dynamics, the stability and bifuraction behavior in a semiconductor ring laser are analyzed and calculated in this paper. The calculated results show that the ring laser can undergoes the Hopf bifurcation by changing pump parameters which can lead the complex nonlinear movement such as limit cycle and Chaos. The effects of backscatter parameters on the operation regions are also calculated The calculated results show that the change of backscatter parameter can result different dynamics behaviors including bifurcation. At last the theoretical result is compared with experiment. The device process and structure is described and the experiment result agree with our theory.

An inductorless CMOS limiting amplifier with stream-mode active feedback

We present an inductorless circuit technique for a CMOS limiting amplifier (LA), which consists of an input buffer, third-order broadband gain stages, and an output buffer for driving 50-Ω transmission lines. By employing stream-mode active feedback with negative capacitance circuit (NCC), the bandwidth of the proposed circuit can be effectively enhanced while maintaining a flat frequency response within the −3 dB bandwidth. Based on TSMC 0.18-μm CMOS process, the proposed LA circuit is optimized and implemented. The measurement results shown that the −3 dB bandwidth is 7.2GHz with a voltage gain of 41 dB, and a data rate of 9Gb/s is successfully achieved. The fluctuation of the group delay is less than 225 ps, and the maximum output voltage is 1Vpp. The measured noise figure of the LA circuit is about 10 dB. Due to the absence of spiral inductors, the die only occupies a core size of 0.3 × 0.2mm2, and consumes 79mW from a 1.8V supply voltage.

90° and 180° phase shifter using an arbitrary phase-difference coupled-line structure

In this paper, an arbitrary phase-difference structure using short-circuit stubs and coupled-line with weak coupling is presented. Compared with conventional coupled-line phase shifters, the proposed coupled-line configuration covers a wide phase range over a broad band. The simulation exhibits a phase range from 15 degrees to 180 degrees. To verified the configuration, 90 degrees and 180 degrees phase shifters are fabricated and measured. According to the measurement results, both 90 degrees and 180 degrees phase shifters achieve bandwidths over 60% with in-band performance of return loss greater than 10 dB, insertion loss less than 1 dB, and phase deviation less than +/- 5 degrees.

High Optical Power Density Forward-Biased Silicon LEDs in Standard CMOS Process

This letter presents three low-operating-voltage silicon-based light-emitting devices (Si-LEDs) designed and made in a commercial standard 0.18-μm CMOS process without any modification. The Si-LEDs with a new threeterminal and wedge-shaped forward-biased carrier-injection-type p⁺-n junction structure, have high optical powers. The output power increases by two orders of magnitude up to 1.78 μW without saturation when the forward current is increased from 20 mA to 200 mA. The light-emitting area is the n-type drift region between the n⁺ region and p⁺ region. When the forward current increases to 200 mA, the optical power density exceeds 30 nW · μm^-2 the power conversion efficiency and external quantum efficiency are ~2 × 10^-6 and 8.3 × 10^-6, respectively, higher than all other forward-biased Si-LEDs previously reported to have used CMOS processes without any modification.

A millimeter wave linear superposition oscillator in 0.18 μm CMOS technology

This paper presents a millimeter wave (mm-wave) oscillator that generates signal at 36.56 GHz. The mm-wave oscillator is realized in a UMC 0.18 μm CMOS process. The linear superposition (LS) technique breaks through the limit of cut-off frequency (fT), and realizes a much higher oscillation than fT. Measurement results show that the LS oscillator produces a calibrated −37.17 dBm output power when biased at 1.8 V; the output power of fundamental signal is −10.85 dBm after calibration. The measured phase noise at 1 MHz frequency offset is −112.54 dBc/Hz at the frequency of 9.14 GHz. This circuit can be properly applied to mm-wave communication systems with advantages of low cost and high integration density.