The output envelope waveforms of the delta-sigma modulated class D series resonant inverter is analyzed, compared, and discussed based on the simulation results with Matlab Simulink simulator. The class D inverter operating at 200 kHz generates 50 Hz envelope waveform through the additional switching legs. Firstly, the relationship between the feed-back gain of the delta-sigma modulator and the output envelope waveforms is clarified. Secondly, the variable parameters are expanded to the loaded Q-factor QL. For QL= 10 to 10000, the output waveforms are analyzed. The simulation results show that THD is held under 3 % from QL= 50 to 100. The obtained envelope waveform is highly qualified as an ac power source

Class E isolated DC-DC converters regulating the output voltage at fixed switching frequency are presented and experimental results given. They consist of class E series resonant inverter, high-frequency transformer and the controllable class E low dv/dt synchronous rectifier. By controlling the conduction time of a controlled switch in rectifier, high-frequency ac current will be rectified and the output voltage can be controlled or regulated in the same time. By parallel connection of the rectifiers at each secondary coil of transformer and applying the PWM control to each rectifier, the circuits supplies and regulates the multiple output voltages at a fixed switching frequency and maintains the ZVS condition of all switches from full-load to open-load.

The extended-range time-shared code tracking loop for frequency hopped signals has been presented and analyzed under the assumption of white Gaussian noise at the input to the loop. The code tracking jitter performance of the loop has been derived and compared to that of the traditional time-shared loop. The results show that the presented loop can have a 5/2 times wider tracking range without the serious jitter performance degradation.

An optical code-division multiple-access (CDMA) system with double optical hard-limiters is proposed where the optical hard-limiters are placed before and after an optical correlator. Moreover, the-effect of the optical hard-limiter on the performance of the optical synchronous CDMA systems using modified prime sequence codes as signature codes is analyzed under the assumption of a Poisson shot noise model for the receiver photodetector where the noise due to the detector dark currents exists. We evaluate the performance under average power and bit rate constraints. Our results show that using the single optical hard-limiter slightly degrades the performance of the optical CDMA systems under the assumption of Poisson shot noise model for the receiver photodetector where the noise due to the detector dark currents exists. Moreover, we show that the optical CDMA systems with double optical hard-limiters have better performance than other conventional CDMA systems with and without the optical hard-limiter when the number of simultaneous users is not so large.

Class E switches have many advantages in comparison with PWM switches. Their low switching losses allow for high-efficiency operation at high frequency. They can operate with low electro-magnetic interference (EMI). In addition, class E synchronous rectifier has the advantage of low power dissipation in the devices. So it is effective especially in low power circuits. On the other hand, thinned-out method can regulate the output voltage easily by adding a simple logic circuit to the drive circuit. In this paper, we propose to apply the thinned-out method to a class E synchronous rectifier. The experimental circuit is Class E/sup 2/ resonant dc/dc converter composed of a basic class E inverter and a class E synchronous rectifier. The circuit can regulate the output voltage by controlling (thinning-out) the drive voltage waveforms of the MOSFET in the synchronous rectifier. Some experimental results are shown, and compared with other circuits. At low output power less than 0.4 W, it was maintained over 60 percent for varying the output voltage from 3.0 V to 2.1 V. The maximum measured efficiency is 78 percent.

Weak signal detection is a basic and important problem in radar systems. The detectable range of a radar is determined by the radar equation. This equation shows that the performance of a radar is improved by increasing the receiver output SNR. For the purpose of improving the SNR, the process called "integration of pulses" has been used. We propose new methods based on the wavelet transform for the improvement of the SNR. The wavelet transform is a tool for time-frequency domain signal analysis and is sensitive to the transient signals. By computer simulations, we show that the receiver output SNR after the wavelet transform is applied becomes about 8 dB greater than that of the original signals. This value corresponds to a 60 percent improvement of the radar detectable range.>

There have been many investigations of the mutual synchronization of oscillators. In this study we consider N oscillators which have the same natural frequency, mutually coupled by one negative resistor. In this system, according to the negative range of the coupling negative resistor, we can observe various interesting synchronization phenomena, because this system tends to minimize the power consumption in the coupling negative resistor. Especially when the I-V characteristics of the coupling negative resistor are not third-power, but linear and negative, this system tends to be stable by producing the power in the coupling one. The phase states are changed according to the negative range of the coupling negative resistor.>

A new class D type tuned power amplifier is proposed. It can operate at a far higher frequency (above 1 MHz) than a conventional class D one. This can be realized by applying the class E switching conditions to each switch. This circuit is very similar to class D amplifier but has a shunt capacitor in each switch device. The analysis, design procedure and experimental results are given. The measured efficiency was over 96 percent at 1 MHz.>

There have been many investigations of the mutual synchronization of oscillators. Especially, we have analyzed N van der Pol type LC oscillators coupled by one resistor, and confirmed that this system can take a huge number of steady states. In this study, we analyze N Wien-bridge oscillators with the same natural frequency mutually coupled by one resister by both of computer calculations and circuit experiments. Because there is no inductor in this system, it is suitable for VLSI implementation. Moreover, the system has many more phase states than that of the system with van der Pol type LC oscillators when N is not so large. So we can utilize this system as a structural element of cellular neural networks.>

In this study, simultaneous asynchronous oscillations of chaos observed in a simple autonomous circuit are investigated by both of circuit experiments and computer calculations. This circuit consists of two nonlinear subcircuits having different oscillation frequencies coupled by one linear negative resistor. In the case that oscillation frequencies of two subcircuits are quite different, both subcircuits exhibit asynchronous chaos simultaneously. Namely, the oscillation is almost divided into two different kinds of chaos, one includes many lower frequency components and the other one includes many higher frequency components. We call this interesting phenomenon as twin chaos. Moreover, as the different between oscillation frequencies of two subcircuits decreases, two difference kinds of chaos interfere mutually. Finally, twin chaos disappears and chaos which is the same as the case of one subcircuit appears due to mutual leading-in.>

The resequencing delay for a queueing system with multiple servers under threshold-type scheduling is analyzed. The general expressions for the average total delay, which is the sum of resequencing delay and queuing delay, are derived. The expressions are also applicable to the conventional M/M/n queuing system as the special case of zero-threshold policy. Next, the numerical calculation is carried out for a queuing system with three servers under a threshold-type schedule to consider the impact of the multiple thresholds on the average resequencing delay. It is found that the resequencing delay as well as the queuing delay for a queuing system with multiple servers of different service rates can be reduced under threshold-type scheduling by selecting the threshold values appropriately. Threshold-type scheduling is more effective in reducing the resequencing delay compared to the queuing delay, especially in the region of modest traffic intensity and as the difference in the service rates becomes larger.>

A carrier slot setting plan is proposed to reduce intermodulation (IM) effects for satellite single-channel-per-carrier (SCPC) systems. Carrier slots are divided into blocks and slight frequency gaps are set among blocks. This setting introduces frequency offset between the center frequencies of carrier slots and the center frequencies of the IM components. A method of deriving optimum division in order to derive the upper bound of improvement of the C/IM ratio in the worst channel is developed. The results show that the setting plan achieves significant improvement of IM effects at a cost of only slight bandwidth expansion, even in fully loaded SCPC systems.>

An analysis is made of the performance of three types of quadrature partial response signaling (QPRS) systems using complex one-sided and two-sided transversal filters with additional decision-feedback (DF) taps in the presence of single continuous wave (CW) interference and additive white Gaussian noise. It is found that both DF filtered noise which is necessarily colored by passing through the QPRS receive filter, while decoding binary data signals from ternary QPRS signals. It is also shown that the duobinary system has the best performance of the three types of QPRS systems when the frequency of CW interference is low.>

The effect of an arbitrary power-series envelope detector on signal-to-noise ratio (SNR) for non-Gaussian noise is considered. It is found that the insertion of the region of saturation in the input-output characteristic of the power-law envelope detector results in the improvement on the output SNR when input SNR is large.

To enable differential detection of coincident, hard-limited, and reduced sidelobe QPSK type of signals, we introduce asymmetrical pulse shapes. This asymmetry in theIandQbaseband channels leads to coincident (unstaggered) QPSK system applications. We consider the bit error probability performance of these modulation schemes on a hardlimited channel in the presence of uplink and downlink additive Gaussian noise. It is found that the unstaggered QPSK modulation with the asymmetrical pulse has better bit error probability performance than QPSK and staggered QORC.

This correspondence describes staggered quadrature overlapped squared raised-cosine (QOSRC) modulation. The power spectrum of QOSRC attains good spectral characteristics over a bandpass hardlimited channel compared to quadrature overlapped raised-cosine (QORC) modulation because of less fluctuation of the signal envelope. It is found that QOSRC has better bit error probability performance than QORC.

This correspondence describes modified QORC (MQORC) modulation. The power spectral density of MQORC is shown to take on the form of the product of the QPSK and SFSK spectra, which attains good spectral characteristics. We show that the bandpass hard-limited staggered MQORC tends to keep its sidelobes suppressed, and therefore, its sidelobes drop off faster compared to staggered QORC.

The effects of bandpass limiters onMth phase tracking systems in the presence of multiple sinusoidal interferences and additive Gaussian noise are considered. We derive general expressions for the ratio of the output to the input SNR (the SNR ratio) for anMth-power tracking loop with and without a bandpass limiter. The numerical calculations for the squaring limited and fourth-power limited PLL's in the presence of multiple sinusoidal interferences and noise are carried out, and the results are compared to those for similar loops without limiters. It is found that sinusoidal interference causes the limit of the SNR ratio for infinite carrier-to-noise ratio (CNR) to be no longer consistent with that for only Gaussian noise. The SNR ratio is degraded more as the carrier-to-interference ratio (CIR) decreases and the number of sinusoidal interferences increases. Furthermore, it is found that for the fourth-power PLL, the limiter does not always enhance the output SNR at moderate to strong input SNR's in the presence of sinusoidal interference.

This paper describes new ways to construct a rewritable programmable logic array (R-PLA) of current mode logic (CML) and to control READ/WRITE operations of the R-PLA. The R-PLA is constructed by splitting a conventional Random Access Memory (RAM) of CML into two parts. Therefore, each cell structure of the new R-PLA is identified with that of the conventional RAM, differing from a complicated cell structure proposed in the past. Because of the identification the comparison for the number of cells between the new R-PLA and the RAM becomes possible according to the historical discussions of the PLA and the memory. It will be demonstrated logically and electrically that SEARCH and READ parts of the new R-PLA can perform logic-in-memory without using special AND gates in each cell in the READ mode and can enter a WRITE data from a word direction in the WRITE mode.

The effects of thenth law amplifier on signal-to-noise ratio has not been represented as a function of the input signal-to-noise ratio when the input of the nonlinear device contains nonGaussian noise. In this paper, we analyze these effects and determine the improvement factor represented by the ratio of the output SNR to the input SNR. The results are illustrated by the calculation of the improvement factor for the cases where the input noise amplitude distributions are the uniform distribution, the triangle distribution, and the Rician distribution.

Phase-locked loops have been used in various parts of telecommunication systems because of their wide applicability to bit synchronization and FM- and PM-demodulation, etc. Several types of digital phase-locked loops (DPLL's) have also been studied due to the increased reliability and decreased cost of integrated digital circuitry. DPLL's of the type employing binary quantized phase detection and discrete phase adjustments have been utilized for detection of a binary signal or suppression of phase jitter in data-transmission techniques. Unfortunately the width of the locking-range and the ability to suppress phase jitter are contrary to each other, and furthermore, the capacity for jitter suppression rapidly lowers as the frequency of input signal deviates from a free-running frequency of the loop. To improve these vicious properties, a DPLL employing a new type of sequential loop filter is proposed in this paper. The sequential filter controls the properties of itself asymmetrically, depending on the input and output phase distributions to keep the output phase at the center of input phase distribution. The loop performance is analyzed theoretically, experimentally, and by computer simulation in the presence of random Gaussian phase jitter. It is shown that the loop has satisfactory performance as a DPLL used for phase jitter suppression.

Summary form only given, as follows. A vibration pick-up type ear microphone was developed in order to make howlingless,mask and free hand microphones or the like. Instead of monodirectional, noise cancelling, laryngeal and forehead microphone, this microphone is made by use of a pie3o element which is put in the ear along the canal and picks up the bone conducted sound by the principle of acceleration type vibration pick-up. By use of this newly developed microphone, phonating aid for patients with highly disturbed voices, loudspeaker built in gas masks, microphones used in airports, microphones for patrolling cars and wireless communicating apparatuses employed in industry or constructive fields have been designed and plays a very important role in daily use.