An ultrabroadband silicon polarization beam splitter (PBS) based on a wavelength-insensitive coupler is fabricated by a standard complementary metal oxide semiconductor technology. The PBS has three identical directional couplers and two identical delay lines with a point symmetric layout. We experimentally demonstrate the broadband operation of the PBS. The crosstalk is less than −12 dB for both TE and TM modes over the wavelength range from 1532 nm to 1649 nm. Additionally, we theoretically discuss a tunability of the PBS for the first time.
A gain-clamped erbium-doped fiber amplifier (GC-EDFA) can effectively suppress gain variations and optical surges that are often induced in the amplification of optical burst signals. In this paper, we demonstrate a simple and effective GC-EDFA using a Sagnac-loop-type EDFA with a low-reflectivity fiber Bragg grating (FBG). The gain-clamped characteristics and the experimental results of the dynamic response for an optical burst signal are presented.
The turn-off of high voltage diode under over-stress condition may lead to the diode destruction, which appears at the edge of termination or in the active region. The diode destruction behaviors related to current filament, electric field and maximum temperature are investigated by electrothermal simulation. The results show that the electric field punch-through to the termination surface is unavoidable. The disappearance of current filament at the edge of termination should be a self-stabilizing mechanism because of the extraction of carriers. The reasons for leading to the diode destruction at the edge of termination or in the active region are found.
A novel single-feed circularly polarized (CP) rectangular dielectric resonator antenna (RDRA) based on dual mode slot-line square ring resonator (SSRR) is proposed. The dual mode SSRR loaded with a perturbation is used to excite the TEx111 mode and TEy111 mode of rectangular dielectric resonator (RDR) simultaneously. By selecting a suitable size of the perturbation, the orthogonal degenerate modes of the SSRR are obtained. Accordingly, the CP radiation pattern of the proposed RDRA is generated from the orthogonal degenerate modes of the SSRR. A prototype is designed and measured. The RDRA has a wide impedance bandwidth of 14.28% (3.16–3.66 GHz). The achieved 3 dB Axial Ratio (AR) bandwidth of the RDRA is about 100 MHz at 3.5 GHz. With the advantages of compact structure, CP performance and easy fabrication, this structure can be a good candidate for 5G communication system in the future.
A wide tuning range frequency enhanced two stage ring voltage controlled oscillator (VCO) is proposed in this letter. The proposed delay cell increases the transmission gain by inserting a resistor between input and output, which consumes lower power to generate same oscillating frequency. A rail-to-rail effective voltage tuning range is obtained by both tuning of tail current and the strength of cross coupled latch. It is important for advanced process, which has low standard supply voltage and high threshold voltage. The proposed VCO is fabricated in TSMC 40 nm CMOS technology. The measured phase noise of proposed VCO is −98.05 dBc/Hz at 1 MHz offset with 1.38 GHz carrier frequency while consuming 1.1 mW from a 1.1 V standard supply. The figure of merit (FoM) is 160.4 dBc/Hz.
A dynamic current injection charge pump (DCI-CP) is proposed to obtain perfect dynamic current match in this paper. In the proposed DCI-CP, dynamic injection current which includes positive injection current and negative injection current is generated to compensate the dynamic current mismatch. To verify the proposed DCI-CP, a CPPLL is fabricated in SMIC 0.18-µm CMOS process. Measurement results show that it synthesizes frequency from 0.6 to 1.3 GHz with a supply voltage of 1.8 V, consuming 4.7 mW. Simulation results show the dynamic current mismatching of proposed DCI-CP is as low as 4 nA even in the worst case. The measurement reference spur achieves −74 dBc at 1.1 GHz oscillation frequency, of which the maximum and minimum reduction are 9 dB and 3 dB, respectively. The phase noise achieves −98.5 dBc/Hz @1 MHz offset. The core occupies a die area of 0.154 mm2 totally.
A base resistance controlled thyristor with semi-superjunction (Semi-SJ BRT) is proposed in this paper. The highly doped P-pillar in drift region extracts injected holes into thyristor, then hole current density in thyristor will be improved and parasitic transistor is significantly suppressed. Meanwhile, highly doped drift region reduces drift resistance, then thyristor trigger current is enhanced. Snapback is greatly suppressed. In addition, much more minority carriers will be extracted due to charge coupling effect in drift region. Turn-off loss is reduced and trade-off performance is improved. Numerical simulation results show that, when the pillar doping level is higher than 1.0 × 1015 cm−3, snapback-free can be realized and turn-off loss can be reduced by 22.28%.
We present a methodology to define and distinguish the column random telegraph noise (RTS) derived from column bitline bias and comparator input transistors only based on the digital output data of each pixel. Many test experiments were conducted on the CMOS image sensor (CIS) chips fabricated with Dongbu 0.13 um, 1P5M process technology. According to the experiments, the threshold voltage and the channel length of the transistors have a significant influence on the intensity of the column RTS. Large channel length and proper threshold voltage, 0.15 V to 0.3 V for most cases, mean a low level of column RTS.
The substrate integrated waveguide (SIW) technology is promising in millimeter wave circuit design because of its low radiation loss and easy manufacturing. In this letter, an SIW filter with novel coupling-enhanced semicircle slots is presented. The coupling coefficients between resonators can be enhanced by 115% with a one-octave tuning range. To demonstrate the proposed concept, a 4-pole filter prototype is designed and fabricated. The measured results show excellent agreement with the simulated results.
We observe multimodal interference in single-mode-multimode-single-mode sensors comprising short polymer optical fibers (POFs) with lengths from 100 mm down to 7 mm. Characteristic spectral peaks/dips are observed not in the conventionally used telecom band but around 1000 nm. We find that the dip wavelength depends on temperature but that the sensitivity is much lower than those obtained in the longer wavelength range when longer POFs are used. We discuss the possibility that, even with the reduced sensitivity, our success in observing multimodal interference in millimeter-long optical fibers will be a basis toward the combined use of frequency and intensity information in conventional fiber-optic single-point sensors for discriminative measurement of multiple physical parameters.
P-hit and N-hit single-event transients are investigated using heavy ion microbeam. A novel layout placement was implemented in the test chip to distinguish SETs originating from P-hit and N-hit. Experimental results indicate both the P-hit and N-hit SETs show an exponential-like distribution in all target circuits. The SET cross sections and the average pulse width for P-hit and N-hit are also investigated. The well process, the transistor size and the layout topology significantly impact on the cross sections. Only the transistor size impacts on the average pulse width at low LET.
Recently proposed common hardware Trojan detection methods can detect wide range of Trojan types, however, there is no explicit detection method for specific Trojan types. These types of Trojan lead to low detection efficiency due to variety of categories and complex features. Keeping in view the special characteristics of Fault Attack Hardware Trojan (FAHT), a method for detection of FAHT is proposed in this letter. Proposed methodology uses ring Oscillator detection circuit that can detect extra logic gate on original cipher circuit where each byte is not required to be injected into the circuit. The experiments show that when the Trojan circuit of area 0.0495% is implanted into the original AES circuit, the detection method in this paper can detect them successfully. In addition, the proposed detection approach has high flexibility to implement in other cipher circuit.