In this paper, a novel trench MOS barrier Schottky contact super barrier rectifier (TMB-SSBR) is proposed by combining the advantages of vertical SSBR and conventional TMBS. The operation mechanism and simulation verification are presented. TMB-SSBR consists of MOS trenches with a vertical SSBR grid which replaces the Schottky diode in the mesa of a TMBS. Due to the presence of top p-n junction in the proposed TMB-SSBR, the image force barrier lowering effect is eliminated, the pinching off electric field effect by MOS trenches is weakened, so that the mesa surface electric field is much larger than that in conventional TMBS. Therefore, the mesa width is enlarged and the n-drift concentration is slightly increased, which results in a low specific on-resistance and a good tradeoff between reverse leakage currents and forward voltages. Compared to a conventional TMBS, simulation results show that, with the same breakdown voltage of 124V and the same reverse leakage current at room temperature, TMB-SSBR increases the figure of merit (FOM, equates to VB2/Ron, sp) by 25.5%, and decreases the reverse leakage by 33.3% at the temperature of 423K. Just like the development from SBD to TMBS, from TMBS to TMB-SSBR also brings obvious improvement of performance.

A novel charge pump, Capacitance Varying Charge Pump (CVCP) is proposed. This charge pump is composed of variable capacitors and rectifiers, and the charge transfer is attained by changing the capacitance values in a manner similar to peristaltic pumps. The analysis of multi-stage CVCP reveals that the output voltage is exponentially dependent on the stage number. Thus, compared with the Dickson charge pump, this charge pump has an advantage in generating high voltages with small stages. As a practical example of CVCP, we present an implementation realized by a MEMS (Micro-Electro-Mechanical Systems) technology. Here, the variable capacitor is enabled by a comb-capacitor attached to a high-quality factor resonator. As the rectifier, a PN-junction diode formed in the MEMS layer is used. Simulations including the mechanical elements are carried out for this MEMS version of CVCP. The simulation results on the output voltage and load characteristics are shown to coincide well with the theoretical estimations. The MEMS CVCP is suited for MEMS devices and vibration energy harvesters.

Series-connection of resonant-tunneling diodes (RTDs) has been considered to be efficient in upgrading the output power when it is introduced to oscillator architecture. This work is for clarifying the same architecture also contributes to increasing oscillation frequency because the device parasitic capacitance is reduced M times for M series-connected RTD oscillator. Although this mechanism is expected to be universal, we restrict the discussion to the recently proposed multiphase oscillator utilizing an RTD oscillator lattice loop. After explaining the operation principle, we evaluate how the oscillation frequency depends on the number of series-connected RTDs through full-wave calculations. In addition, the essential dynamics were validated experimentally in breadboarded multiphase oscillators using Esaki diodes in place of RTDs.

We achieved detailed characterization of resonant tunneling chaos generator circuits in microwave frequency range. The circuit is analogous to Duffing oscillator, where the third-order nonlinear potential term is emulated by the nonlinear current-voltage curve of the resonant tunneling diode. The circuit includes a periodic reset mechanism to output identical chaos signal, which is essential to observe chaos signal on a sampling oscilloscope. Though this was shown to be effective in our previous papers, the length of the waveforms to observe is limited to rather short period, and it was unclear if this technique can be used for detailed characterization of such high-frequency chaos. In this paper, we improved the circuit design to observe longer waveforms, and demonstrated that the detailed characterization is possible using this periodic resetting technique with a sampling oscilloscope. The hybrid integration scheme is also used in this paper, which allows the easiest and shortest way to mimic a circuit as per circuit design, and precise estimation of circuit parameters aiming to eliminate circuit-related abnormalities. We provide deep insight into the dynamics associated with our circuit, starting from the single period, double period, chaos, and triple period regimes, by extracting power spectra, return maps, phase portraits, and bifurcation diagrams from acquired time series using sampling oscilloscope. Our method to study microwave chaotic signals can be applied to much higher frequency ranges, such as THz frequency range.

This study proposes a new structure of a single-shunt rectifier circuit that can reduce circuit loss and improve efficiency over the conventional structure. The proposed structure can provide impedance matching to the measurement system (or receiving antenna) without the use of conventional matching circuits, such as stubs and tapers. The proposed structure can simultaneously perform full-wave rectification and impedance matching by placing a feeding point on the output filter's λ/4 transmission line. We use circuit simulation to compare the RF-DC conversion efficiency and circuit loss of the conventional and proposed structures. The simulation results show that the proposed structure has lower circuit loss and higher RF-DC conversion efficiency than the conventional structure. We fabricate the proposed rectifier circuit using a GaAs Schottky barrier diode. The simulation and measurement results show that the single-shunt rectifier circuit's proposed structure is capable of rectification and impedance matching. The fabricated rectifier circuit's RF-DC conversion efficiency reaches a maximum of 91.0%. This RF-DC conversion efficiency is a world record for 920-MHz band rectifier circuits.

In this paper, a high-efficiency high-power rectenna with a bridge diode and the diode on antenna (DoA) topology is discussed. First, the topologies of rectifiers and rectennas are discussed to indicate the direction for obtaining highly efficient rectification. Rectifiers with well-matched diode pairs, as double voltage and bridge rectifiers, can reactively terminate even order harmonics, and is suitable for highly efficient operation. A rectenna with the DoA topology is suitable for a direct connection between the highly functional antenna and the rectifier diodes to remove lossy circuit portions. Next, the formulas for the rectification efficiency of the bridge rectifier are demonstrated with the behavioral model. The indicated formulas clarify the fundamental limitation on the rectification efficiency, which is the design goal in case of the DoA topology. Finally, we demonstrate a 5.8 GHz band 1 W rectenna with the bridge diode and the DoA topology. The bridge rectifier that is directly connected to the inductive high-impedance antenna achieved a rectification efficiency of 92.8% at an input power of 1 W. This is close to the fundamental limitation due to the diode performance.

S-parameters of InGaAs/InAlAs triple-barrier resonant tunneling diodes (TBRTDs) were measured up to 67 GHz with various mesa areas and various bias voltages. Admittance data of bare TBRTDs are deembedded and evaluated by getting rid of parasitic components with help of electromagnetic simulations for particular fabricated device structures. Admittance spectroscopy up to 67 GHz is applied for bare TBRTDs for the first time and a Kramers-Kronig relation with Lorentzian function is found to be a consistent model for the admittance especially in cases of low bias conditions. Relaxation time included in the Lorentzian function are tentatively evaluated as the order of several pico second.

A hard-type oscillator is defined as an oscillator having stable fixed points within a stable limit cycle. For resonant tunneling diode (RTD) oscillators, using hard-type configuration has a significant advantage that it can suppress spurious oscillations in a bias line. We have fabricated hard-type oscillators using an InGaAs-based RTD, and demonstrated a proper operation. Furthermore, the oscillating properties have been compared with a soft-type oscillator having a same parameters. It has been demonstrated that the same level of the phase noise can be obtained with a much smaller power consumption of approximately 1/20.

A method for detecting the timing of photodiode (PD) saturation without using an in-pixel time-to-digital converter (TDC) is proposed. Detecting PD saturation time is an approach to extend the dynamic range of a CMOS image sensor (CIS) without multiple exposures. In addition to accumulated charges in a PD, PD saturation time can be used as a signal related to light intensity. However, in previously reported CISs with detecting PD saturation time, an in-pixel TDC is used to detect and store PD saturation time. That makes the resolution of a CIS lower because an in-pixel TDC requires a large area. As for the proposed pixel circuit, PD saturation time is detected and stored as a voltage in a capacitor. The voltage is read and converted to a digital code by a column ADC after an exposure. As a result, an in-pixel TDC is not required. A signal-processing and calibration method for combining two signals, which are saturation time and accumulated charges, linearly are also proposed. Circuit simulations confirmed that the proposed method extends the dynamic range by 36 dB and its total dynamic range to 95 dB. Effectiveness of the calibration was also confirmed through circuit simulations.

This paper theoretically presents that a terahertz (THz) oscillator using a resonant tunneling diode (RTD) and a rectangular cavity, which has previously been proposed, can radiate high output power by the impedance matching between RTD and load through metal-insulator-metal (MIM) capacitors. Based on an established equivalent-circuit model, an equation for output power has been deduced. By changing MIM capacitors, a matching point can be derived for various sizes of rectangular-cavity resonator. Simulation results show that high output power is possible by long cavity. For example, a high output power of 5 mW is expected at 1 THz.

A scheme is proposed for generation of large-amplitude short pulses using a transmission line with regularly spaced series-connected tunnel diodes (TDs). In the case where the loaded TD is unique, it is established that the leading edge of the inputted pulse moves slower than the trailing edge, when the pulse amplitude exceeds the peak voltage of the loaded TD; therefore, the pulse width is autonomously reduced through propagation in the line. In this study, we find that this property is true even when the several series-connected TDs are loaded periodically. By these mechanisms, the TD line succeeds in generating large and short pulses. Herein, we clarify the design criteria of the TD line, together with both numerical and experimental validation.

In this paper, a compact microwave push-push oscillator based on a resonant tunneling diode (RTD) has been fabricated and demonstrated. A symmetrical spiral inductor structure has been used in order to reduce a chip area. The designed symmetric inductor is integrated into the InP-based RTD monolithic microwave integrated circuit (MMIC) technology. The circuit occupies a compact active area of 0.088 mm2 by employing symmetric inductor. The fabricated RTD oscillator shows an extremely low DC power consumption of 87 µW at an applied voltage of 0.47 V with good figure-of-merit (FOM) of -191 dBc/Hz at an oscillation frequency of 27 GHz. This is the first implementation as the RTD push-push oscillator with the symmetrical spiral inductor.

The transition dynamics of a multistable tunnel-diode oscillator is characterized for modulating amplitude of outputted oscillatory signal. The base oscillator possesses fixed-point and limit-cycle stable points for a unique bias voltage. Switching these two stable points by external signal can render an efficient method for modulation of output amplitude. The time required for state transition is expected to be dominated by the aftereffect of the limiting point. However, it is found that its influence decreases exponentially with respect to the amplitude of external signal. Herein, we first describe numerically the pulse generation scheme with the transition dynamics of the oscillator and then validate it with several time-domain measurements using a test circuit.

In this paper, the influence of high-temperature sputtering on the nitrogen-doped (N-doped) LaB6 thin film formation utilizing RF sputtering was investigated. The N-doped LaB6/SiO2/p-Si(100) MOS diode and N-doped LaB6/p-Si(100) of Schottky diode were fabricated. A 30 nm thick N-doped LaB6 thin film was deposited from room temperature (RT) to 150°C. It was found that the resistivity was decreased from 1.5 mΩcm to 0.8 mΩcm by increasing deposition temperature from RT to 150°C. The variation of work function was significantly decreased in case that N-doped LaB6 thin film deposited at 150°C. Furthermore, Schottky characteristic was observed by increasing deposition temperature to 150°C. In addition, the crystallinity of N-doped LaB6 thin film was improved by increasing deposition temperature.

This work reports a new technique to suppress the undesirable multiple-triggering effect in the typical diode triggered silicon controlled rectifier (DTSCR), which is frequently used as an ESD protection element in the advanced CMOS technologies. The technique is featured by inserting additional N-Well areas under the N+ region of intrinsic SCR, which helps to improve the substrate resistance. As a consequence, the delay of intrinsic SCR is reduced as the required triggering current is largely decreased and multiple-triggering related higher trigger voltage is removed. The novel DTSCR structures can alter the stacked diodes to achieve the precise trigger voltage to meet different ESD protection requirements. All explored DTSCR structures are fabricated in a 65-nm CMOS process. Transmission-line-pulsing (TLP) and Very-Fast-Transmission-line-pulsing (VF-TLP) test systems are adopted to confirm the validity of this technique and the test results accord well with our analysis.

In partially depleted SOI (PD-SOI) technology, the SCR-based protection device is desired due to its relatively high robustness, but be restricted to use because of its inherent low holding voltage (Vh) and high triggering voltage (Vt1). In this paper, the body-tie side triggering diode inserting silicon controlled rectifier (BSTDISCR) is proposed and verified in 180 nm PD-SOI technology. Compared to the other devices in the same process and other related works, the BSTDISCR presents as a robust and latchup-immune PD-SOI ESD protection device, with appropriate Vt1 of 6.3 V, high Vh of 4.2 V, high normalized second breakdown current (It2), which indicates the ESD protection robustness, of 13.3 mA/µm, low normalized parasitic capacitance of 0.74 fF/µm.

A one-dimensional lattice of tunnel-diode oscillators is investigated for potential high-speed frequency divider. In the evolution of the investigated lattice, the high-frequency oscillation dominates over the low-frequency oscillation. When a base oscillator is connected at the end, and generates oscillatory signals with a frequency higher than that of the synchronous lattice oscillation, the oscillator output begins to move in the lattice. This one-way property guarantees that the oscillation dynamics of the lattice have only slight influence on the oscillator motion. Moreover, counter-moving pulses in the lattice exhibit pair annihilation through head-on collisions. These lattice properties enable an efficient frequency division method. Herein, the operating principles of the frequency divider are described, along with a numerical validation.

An integrated ambient light sensor (ALS) system in low-temperature polycrystalline silicon (LTPS) thin-film-transistor liquid-crystal-displays (TFT-LCDs) is proposed and prototyped in this study. It is designed as a 4-bit (16-step-grayscale) ALS and includes a noise subtraction circuit, a comparator as an analog-to-digital converter (ADC), 4-bit counters, and a parallel-to-serial converter. LTPS lateral p-i-n diodes with a long i-region are employed as photodetectors in the system. An LSI source driver is mounted on the LCD panel with a sensor control block which provides programmable clocks and reference voltages to the ALS circuit on the glass substrate for sensitivity tuning. The reliability tests were conducted for 300 hours with 30000 lux illumination at 70 °C and at -20 °C. The observed deviations of the ALS values for dark, 1000 lux, and 10000 lux were within ±1.

We have investigated post-metallization annealing (PMA) utilizing TiN gate electrode on the thin ferroelectric undoped HfO2 directly deposited on p-Si(100) by RF magnetron sputtering. By post-deposition annealing (PDA) process at 600°C/30 s in N2, the memory window (MW) in the C-V characteristics was observed in the Al/HfO2/p-Si(100) diodes with 15 to 24-nm-thick HfO2. However, it was not obtained when the thickness of HfO2 was 10 nm. On the other hand, the MW was observed for Pt/TiN/HfO2 (10 nm)/p-Si(100) diodes utilizing PMA process at 600°C/30 s. The MW was 0.5 V when the bias voltage was applied from -3 to 3 V.

We numerically demonstrate a possibility on-off keying (OOK) type of modulation over tens gigabits per second for sub-terahertz radiation in our proposed wireless transmitter device structure towards radio over fiber (RoF) technology. The integrated device consists of an InP-based compound semiconductor resonant tunneling diode (RTD) adjacent to an InP-based photo diode (PD), a self-complementary type of bow-tie antenna (BTA), external microstrip lines. These integration structures are carefully designed to obtain robust relaxation oscillation (RO) due to the negative differential conductance (NDC) characteristic of the RTD and the nonlinearity of the NDC. Moreover, the device is designed to exhibit OOK modulation of RO due to photo current from the PD inject into the RTD. Electromagnetic simulations and nonlinear equivalent circuit model of the whole device structure are established to perform large signal analysis numerically with considerations of previously measured characteristics of the triple-barrier RTD.