Valley search aims to find the updated optimal read reference voltage (OPT) that minimizes the raw bit error rate (RBER). In this paper, a valley search algorithm is proposed, which can accurately find the OPT after five read operations through a simple calculation based on cubic polynomial approximation, without traversing all the read voltages between two adjacent program states. Experimental results of TLC chip show that the raw bit error rate after applying this valley search scheme is reduced to 0.183%, which is within the error correcting capability of LDPC (8763, 8272) error correcting code (ECC).
Optical interferometry is promising for noncontact photoacoustic (PA) signal detection; however, the intensity detection of the interference signal makes the system insensitive and unreliable due to fluctuations in the optical path length difference. To address this, a noncontact PA signal detection utilizing an optical digital coherent receiver to acquire the entire quadrature components of the PA signal in self-homodyne mode is proposed and numerically investigated. Simulation results show that by applying a narrow bandwidth probe laser at a linewidth of 33kHz, the signal SNR meets the requirement of a 12-bit quantizer together with 13-dB tolerance to extra-intensity noise.
This paper studies transient thermal characteristics of β-Ga2O3 Schottky barrier diode (SBD) packaged in TO-220. Planar and metal-oxide-semiconductor (MOS) trench anode types are evaluated. Junction temperature is estimated from temperature dependency of forward conduction characteristics in measuring SBD transient thermal characteristics. This paper confirms the completeness of processed Schottky junction on β-Ga2O3 with extracted diode ideal factor and Schottky barrier height of SBDs. The measured transient thermal characteristics of developed β-Ga2O3 SBDs are proved to have higher thermal resistance compared to commercially available SiC SBD and left much to be improved.
TIA (Trans-Impedance Amplifier) is usually selected as the input stage of the up-conversion mixers or the output buffer of the down-conversion mixers. In this paper, we analysis the frequency limitations of the traditional self-biased TIA and propose an applicable model in millimeter-wave band. Then a high and wide IF millimeter-wave/terahertz band up-conversion mixer based on a 55-nm CMOS process is designed. The measured IF 3-dB bandwidth is 10.7GHz, from 23.8GHz to 34.5GHz, and the RF frequency is from 121.5GHz to 132.2GHz. The DC consumption is only 8mW under 1.2-V supply.
In this letter, an explicit and absolutely stable finite-difference time-domain (FDTD) algorithm is designed for electromagnetic analysis. The algorithm works through a structure composed of several vectors and matrices acting on these vectors. Excitation source is linearly approximated in a time interval, fields in the computation domain are expressed by a vector, and these matrices are derived based on the FDTD method. The proposed algorithm solves electromagnetic problems in an explicit way, its time step size is beyond the Courant-Friedrich-Levy (CFL) stability condition and the computation efficiency of the proposed method is also higher than the conventional FDTD method. Two numerical examples are tested and validate that the proposed algorithm can solve electromagnetic problems correctly and also improves calculation efficiency.
Ferroelectric-based Field-Effect Transistors (Fe-based FETs) are emerging devices candidates for energy-efficient circuits. In this paper, a concise logic is proposed, that is, utilizing Fe-based FETs to simplify the circuit composed of traditional Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs), thereby decreasing the number of transistors in the circuit while keeping the circuit function consistent. Further, this proposal decreases the area and the power effectively. Applications of Fe-based FETs are proposed in this research, viz., Negative-capacitance Field-Effect Transistor (NCFET) and hysteretic ferroelectric Field-Effect Transistor (FeFET) are used in the output design of a Look-up Table (LUT) on the basis of concise logic. To improve the driving capability, the output of a LUT requires an NCFET-based sensing amplifier (SA) or a FeFET-based level restorer, either of which satisfies both small-area and energy-efficient properties. That will also decrease the load of the LUT, through comparing an NCFET-based SA with a MOSFETs-based SA, 4 transistors are reduced, 2 transistors at a FeFET-based level restorer are also decreased.
This letter presents a wideband slim monopole antenna operating on very-high-frequency (VHF) and ultra-high-frequency (UHF) bands. The monopole antenna is composed of a slim strip and a meander line loading. The monopole antenna is vertically mounted on the case of the radio station which is served as ground and modified with slots. The method of characteristic mode analysis (CMA) is used to design the proposed antenna. By loading the meander line, the resonant frequency of the characteristic mode 1 of the proposed antenna moves to the lower band and higher modes are effectively excited at the higher band, which leads to a wide impedance bandwidth. Moreover, by loading the slots on the case, the inverse currents of characteristic mode 3 on the case at higher band, having bad effects on radiation patterns, are canceled out. Hence, the gain at horizontal plane at higher band is improved. A prototype of the proposed antenna with a slim structure is fabricated and measured. The bandwidth (VSWR ≤ 3: 1) is 200-550MHz (93.3%). The gain is greater than 0.5 dBi in the working band. The proposed antenna has omnidirectional radiation patterns and is suitable for backpacked radio station applications.
In this letter, the one-twelfth mode of equilateral hexagonal substrate integrated waveguide (TMSIW) is proposed for the first time. Comparing with traditional substrate integrated waveguide (SIW), the size of TWSIW is only 1/12 which is reduced 11/12 while the resonant frequency of TWSIW is almost unchanged. Loading a complementary split-ring resonator (CSRR) structure, the miniaturization is further improved and the filter selectivity is improved. The filter design uses two of TWSIW which is connected with a microstrip line. The structure is not complex, easy to process, low loss, and the passband has a certain bandwidth. After processing and testing, it shows that the measurement results of filter give good agreement with the simulation results. This filter has advantages in all indexes by comparing with other works.
A novel dual-band circularly-polarized frequency reconfigurable microstrip antenna with the feasibility of obtaining a relatively smaller size is proposed and demonstrated. Fed by a Wilkinson power divider with 90° phase difference, the proposed circularly-polarized frequency reconfigurable patch antenna, consisting of a patch radiator etched with a square-ring slot and a double-sided printed DC bias circuit, is designed, analyzed and fabricated. Good agreement between simulated and measured results is observed. Simulation and measurement results reveal that the proposed dual-band circularly polarized (CP) antenna for BeiDou navigation satellite system can provide impedance bandwidths of 4.1% (1.592-1.658GHz) and 5.5% (2.43-2.568GHz) for lower L band and upper S band respectively, as well as 3-dB axial ratio (AR) bandwidths of 1.5% (1.602-1.626GHz) and 1.7% (2.465-2.507GHz) for LHCP and RHCP respectively. Meanwhile, within the effective LHCP/RHCP bandwidths, the proposed antenna has gains from 3.6dBic to 4.2dBic with an average gain of 4.0dBic for LHCP, and gains from 3.3dBic to 3.6dBic with an average gain of 3.4dBic for RHCP, respectively.
We have experimentally investigated the amplitude and phase evolution of a short-pulse propagating through a semiconductor optical amplifier (SOA), by using a spectral retrieving technique. A short-pulse with 20-ps pulse width, which had comb-shaped spectrum, was input to the SOA with gain saturated condition. The amplitude and phase of the output signals were observed by synthesizing the fragments of sliced spectrum which were individually observed by a coherent optical receiver. The phase rotation in time and frequency domain were successfully observed, as well as the amplitude evolution. The gain saturation and nonlinear effect in the SOA induced strong amplitude and phase evolution of spectral comb components as well as generating new frequency components. The experimental results characterized the amplitude and phase evolution of a short-pulse propagating through the SOA.