Article type: LETTER
Subject area: Microwave and millimeter wave devices, circuits, and systems
2015 Volume 12 Issue 2 Pages
Published: 2015 Released on J-STAGE: January 25, 2015 Advance online publication: December 26, 2014
A miniaturized lowpss filter (LPF) with ultra-wide stopband is proposed by using the complementary rectangle split ring defected microstrip structure (CRSR-DMS) and the quad U-shaped defected ground structure (QU-DGS). The presented CRSR-DMS can provide a sharp rejection rate and two obvious attenuation poles while the QU-DGS can produce four independently controlled transmission zeros. Based on the characteristics of the defected structures, the proposed LPF is constructed by using four cascaded CRSR-DMS units and four cascaded QU-DGS units. The measurement result of the designed filter with 3 dB cut-off frequency at 2.0 GHz shows that the obtained 20 dB rejection band ranges from 2.12 GHz to more than 20 GHz within a small circuit area of 0.73λg * 0.13λg, λg being the guided wavelength at 2.12 GHz.
The InP-based pin-photodiode array monolithically integrated with a 90° hybrid and spot-size converters was realized using selective embedding regrowth for compact 100 Gb/s coherent receivers. The low dark current of less than 500 pA up to 85 °C was attained by InP passivation effect in four-channel pin-photodiodes. As a receiver using these photodiode arrays, a receiver responsivity including total loss of 6.7 dB in the 90° hybrid and intrinsic loss of 3 dB in the polarization beam splitter was higher than 0.060 A/W between −5 °C and 85 °C through the integration of the spot-size converter. Responsivity imbalance of the In-phase and Quadrature channels was also less than 0.5 dB over the C-band.
A high-order high-Q closed-loop sigma-delta (ΣΔ) capacitive microaccelerometer interface circuit is presented in this work. The quantization noise in baseband of the interface circuit is greatly suppressed by a high-order loop shaping, and the mechanical noise is deceased by the use of a vacuum-packaged sensor element. A lead compensator is used to damp the high-Q element to guarantee a stable high-order system. The interface circuit is implemented in a standard CMOS process, and the power dissipation is 10 mW from a 5 V supply and sampling frequency of 250 kHz. The high-order high-Q closed-loop ΣΔ capacitive microaccelerometer has a noise floor of 5 µg/Hz1/2 with bandwidth of 600 Hz.
We propose a new low complexity Montgomery algorithm enabling the efficient selection of the quotient value necessary for an exact division in Montgomery multiplication. We also present two new systolic multipliers which use similar data flows as described in the most significant bit (MSB)-first GF(2m) multiplier in . The proposed parallel and serial multipliers have less hardware and time complexities compared to related multiplier. The serial multiplier can be well applied to space-limited hardware. Furthermore, our proposed systolic multipliers include regularity, modularity, local interconnection, and unidirectional data flow features.
To carry out performance evaluation of an asynchronous system, the system is modeled as Time Petri Net (TPN) and an iteration of Petri net simulations produces its performance index. The TPN model needs to satisfy required properties such as deadlock freeness. We proposed a symbolic representation of TPN for SAT-based bounded model checking. In the proposed encoding scheme, firing of transitions and elapsing of place delays are expressed as boolean formulas discretely. Our representation can work with relaxed ∃-step semantics which enables to perform each step by two or more transitions. We applied the encoding to example TPN models and checked the deadlock freeness using SAT solver. The results of experiments demonstrated the effectiveness of the proposed representation.
Cross-borehole pulse radar has been employed to explore an empty tunnel using the fast propagation of its excited pulse through the air region inside the tunnel. However, a partially water-filled tunnel is not properly interpreted yet. An effective conversion model to estimate the water level collected in an empty tunnel is developed using the finite-difference time-domain (FDTD) simulation data. As the collected water level inside the tunnel increases, the depth at the fastest time of peak (TOP) deviates exponentially from that at the fasted time of arrival (TOA). This conversion model renders the collected water level inside the tunnel to be estimated with average error of 0.044 m.
Two new quadrature sinusoidal oscillators using current-feedback operational amplifiers (CFOAs) as an active building block are proposed. The proposed circuits use two CFOAs with the minimum number of passive elements, namely two resistors and two grounded capacitors. The use of only grounded capacitors makes the proposed circuits ideal for integrated circuit implementation. Both proposed circuits offer the advantages of orthogonal control of the oscillation condition and oscillation frequency, availability of two quadrature sinusoidal voltage outputs and low active and passive sensitivity performances. The HSPICE simulation and experimental results are provided to demonstrate the theoretical analysis.
Article type: LETTER
Subject area: Fiber optics, Microwave photonics, Optical interconnection, Photonic signal processing, Photonic integration and systems
2015 Volume 12 Issue 2 Pages
Published: 2015 Released on J-STAGE: January 25, 2015 Advance online publication: January 07, 2015
We develop strain and temperature sensors based on multimode interference in a partially chlorinated graded-index polymer optical fiber (PCGI-POF) and experimentally investigate their sensing performance at room temperature using incident light of ∼1300 nm wavelength. The length of the PCGI-POF was 0.7 m. The measured strain and temperature sensitivities were −4.47 pm/µε and +9.66 nm/°C/m, respectively, the absolute values of which were 0.29 times and over 350 times the values in a silica GI-MMF. This result suggests that the modal interference in PCGI-POFs is potentially applicable to high-sensitivity temperature measurement with low strain sensitivity.