SummaryThe proposed booth decoder/encoder unit is an ultrahigh‐speed unit among the reported ones which was designed by modifying and creating a new format truth table with 0.18 μm CMOS technology. According to the modified truth table, four cases are defined, and a proper circuit for each case is designed. The proposed structure is discussed considering the possible problems such as the swing and discharge problems. The gate‐level delay of the proposed structure and other related works have been calculated and are compared. The propagation delay of the proposed structure has been calculated and simulated to validate the data. To justify the comparisons, other related works have been simulated again with the same condition. The propagation delay of the proposed structure is 226 ps, which is minimum compared to previous related works. The proposed structure reduces the delay by 30–200% comparing related works and also improves the delay of the multiplier 4–21%. The power consumption and the area of the structure are 477 μw and 20 × 18 μm2, respectively. In this paper, Hspice software for simulating, MATLAB for numerical calculations, and Cadence for designing the layout of the proposed structure have been used.
A novel ultra‐high‐speed 5‐2 compressor is presented and discussed in this paper. The proposed structure is developed by modifying the truth table focusing on the carry rippling problem. By reducing the number of the states in the truth table and the complexity of the structure, the total delay is reduced while the power and active area are also improved. The proposed compressor is compared with the best recently reported ones where the designed architecture shows 9%–80% improvement in power delay product (PDP). For a better demonstration of the advantages, the proposed structure is placed in the body of a 16 × 16‐bit multiplier and is compared with the other multipliers consisting of the other 5‐2 compressor architectures. The results indicate an improvement equal to 13%. It must also be mentioned that the gate‐level delay calculation is emphasized in this paper, where a precise estimation method is utilized considering the capacitances at the middle‐stage nodes. Based on the calculations, the designed circuit has the minimum gate‐level delay compared to the other related works due to its minimal intermediate connections. For simulating the proposed structure, a standard CMOS 0.18‐μm process along with HSPICE software is used, where the results show a delay of 266.5 ps with a power consumption of 164 μw.
To obtain certain information such as metabolic concentrations in neural or muscular tissues and other applications, it is necessary to design nuclear magnetic resonance (NMR) transmitters/receivers capable of operating at multiple frequencies, while maintaining a good performance at each frequencies. We have proposed a new NMR receiver front-end for simultaneous detection of proton and carbon nucleus. The system consists of two reception coils for carbon and hydrogen analysis, a multiband low-noise amplifier (LNA) for increasing the voltage level and a network for passive amplification, noise figure minimization and decreasing mutuality effect between two coils. The proposed coil set was designed, simulated and analyzed and also the signal to noise ratio (SNR) with quality factor have been calculated for it by simulation. The LNA has been designed in a 0.18[Formula: see text][Formula: see text]m CMOS technology and its gains for carbon and proton NMR signals are 45 and 48[Formula: see text]dB, respectively. The input referred noise for both signals is lower than 0.4[Formula: see text]nV/sqrt(Hz) and the power consumption is 4 mA from a single 1.8[Formula: see text]V supply.
NMR is one of the important analytic tools which is used to obtain certain information such as metabolic concentrations in neural or muscular tissues. In some other important applications such as proton decoupling, it is necessary to design NMR transmitters/receivers capable of operating at multiple frequencies, while maintaining a good performance at each frequency. In this work, a new nuclear magnetic resonance (NMR) receiver microcoil based on MEMS technology is proposed. The designed structure uses MEMS microswitches with low contact resistance and NMR-based actuation mechanism. The proposed device can detect carbon (13C), proton (1H), and phosphorus (31p) nucleus with larmor frequencies of 96.36[Formula: see text]MHz, 383[Formula: see text]MHz, and 155.11[Formula: see text]MHz at 9 T magnetic field, respectively. The designed microcoil achieves three important goals: (1) Getting high SNR, high Q and high filling factor which are key parameters in NMR performance, by changing number of turns. (2) Turning into the array of microcoils to obtain better SNR. (3) Turning into two or three microcoils inside of each other for simultaneous detection. The MEMS microswitch in this paper uses static magnetic field of the NMR for its operation ([Formula: see text]T) which simplifies the switch mechanism. This switch is small (150[Formula: see text][Formula: see text]m[Formula: see text][Formula: see text][Formula: see text]50[Formula: see text][Formula: see text]m[Formula: see text][Formula: see text][Formula: see text]6[Formula: see text][Formula: see text]m), scattering parameters of 43.2[Formula: see text]db isolation and 0.0059 insertion loss and maximum displacement of 2.03[Formula: see text][Formula: see text]m due to the magnetostatic actuation. In this work, the models and investigations are conducted using finite element simulations in COMSOL Multiphysics. The switch scattering parameters are obtained by HFSS 12.0.
In this paper, a tunableMicroElectro Mechanical Systems Nuclear Magnetic Resonance (MEMS NMR) receiver front-end, which consists of three main parts, is presented. In the first part, a proper microcoil for detecting [Formula: see text] and [Formula: see text] with complete specifications regarding the sample is optimized to get the better Signal to Noise Ratio (SNR) and quality factor (Q). In the second part, the passive network is discussed and the amounts of the desired capacitor and the desired tunability range are calculated and based on the calculations and the fabrication process, a new MEMS tunable capacitor is presented. Due to the large capacitance value of the required capacitor, the proposed capacitor has a fixed part with a capacitance value of 28[Formula: see text]pf and a variable part with a tunability range of 193% (2.25[Formula: see text]pf–6.6[Formula: see text]pf) with 1.5 A applied to a thermal actuator. A buckling effect due to the weight of the fingers of the capacitor and thermal stress after the release is analyzed and a fabrication process based on the routine processes is proposed. In the third part, a low noise amplifier (LNA) is presented for the proposed receiver with a gain of 47.6[Formula: see text]dB at the bandwidth of 384 MHz and noise figure of 0.5[Formula: see text][Formula: see text]. In this work, modeling and investigation of surface microcoils and also the capacitor are conducted using finite element simulation in COMSOL Multiphysics and post-processing. The method for obtaining signal sensitivity and SNR of the microcoils are based on the MR signal generation by employing the principle of reciprocity.
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