A novel 3.5-GHz microwave counter using an opto-electronic harmonicheterodyne technique

A novel 3.5-GHz microwave counter using an optoelectronic harmonic heterodyne technique has been demonstrated. The system's performance has been discussed and evaluated, and is viewed as good, in comparison with today's microwave-counting systems. It is believed that this novel device has potential for measuring signals above 100 GHz     

Design Methodology for a 40-GSamples/s Track and Hold Amplifier in 0.18-$muhbox m$SiGe BiCMOS Technology

A 40-GSamples/s track and hold amplifier (THA) is designed and fabricated in 0.18-$muhbox m$SiGe BiCMOS and operates from a 3.6-V supply. The total power consumption is 540 mW with a chip area of 1.1$hbox mm^2$. Time domain measurements demonstrate 40-GHz sampling and$ S$-parameter measurements show a 3-dB bandwidth of 43 GHz in track mode. For 19-GHz input signals, a total harmonic distortion of$-hbox 27~dB$at the 1dB compression point has been measured and a spurious-free dynamic range of 35 dB has been achieved.     

Microwave harmonic frequency generation utilizing the properties of an optical phase Modulator

New techniques to generate a harmonic microwave frequency modulated on an optical carrier are presented. All these techniques utilize the polarization-dependent properties of a LiNbO/sub 3/-phase modulator and manage to achieve 40-GHz modulation using only 10-GHz electronics. The signal quality of the generated frequency is mainly determined by the 10-GHz signal generator, and the suppression of undesired lower order harmonic frequencies exceeds 30 dB.     

Phase-plane analysis of rational harmonic mode-locking in an erbium-doped fiber ring laser

We investigate the system performance of rational harmonic mode-locking in an erbium-doped fiber ring laser using the phase-plane technique of the nonlinear control engineering. Contributions from harmonic distortion, a Gaussian-like modulating signal, and its duty cycle to the system behavior are studied. We also demonstrate 660/spl times/ and 1230/spl times/ repetition rate multiplications on a 100-MHz pulse train generated from an active harmonically mode-locked fiber ring laser, and we hence achieve 66- and 123-GHz pulse operations by using the above-mentioned technique. It has been found out that the maximum obtainable rational harmonic order is limited by the harmonic distortion of the system as well as the pulse width of the generated signal, which in turn is determined by the duty cycle of the modulating signal. Furthermore, the rational harmonic order increases the complexity of the pulse formation process and hence challenges its stability.     

Broad-Band Bias-Current-Tuned IMPATT Oscillator for 100-200 GHz

Broad-band bias-current-tuned IMPATT oscillators rising harmonic oscillations have been realized for the short-millimeter wave-length region (100-300 GHz). The relationship between diode and wave-guide parameters (breakdown voltage, junction diameter, and waveguide cutoff frequency) to obtain broad-band tunable oscillations is investigated theoretically and experimentally. Consequently, a tuning bandwidth of 35 GHz is obtained with IMPATT oscillators in the 160-GHz band, and 30 GHz in the 200-GHz band.     

Envelope transient analysis of self-oscillating mixers

In this paper, the envelope-transient method is applied to the analysis of intermodulation distortion in self-oscillating mixers (SOM). A two-tone Fourier-series expansion of the circuit variables with time-varying harmonic components is used with a new initialization technique of the oscillation to avoid convergence toward unstable forced solutions. The two cases of an autonomous oscillation and a sub-synchronized oscillation are studied and compared. In the sub-synchronized SOM, the ranges of sub-synchronized operation in terms of the sub-synchronization generator power and frequency are determined through harmonic balance. The techniques are applied to a SOM with 5.5-GHz input frequency and 0.5-GHz IF. In the case of an autonomous oscillation, two different values of the quality factor of the load circuit are considered. For sub-synchronized operation, a generator is introduced at approximately one-third the self-oscillation frequency. In order to validate the analysis techniques, the circuit has been experimentally characterized in both autonomous and sub-synchronized operation, obtaining very good agreement with the simulation results.     

Design and analysis of a microwave large-range variable phase-shifter based on an injection-locked harmonic self-oscillating mixer

In this letter, a new microwave variable phase-shifter based on an injection-locked harmonic self-oscillating mixer, is presented for its application in an active microstrip phased antenna array. The circuit provides the double functionality of variable phase-shifter and down-converter. Maximum conversion gain is obtained, through the optimization of a new multi-harmonic load at the input-port of the circuit. The ranges of synchronized operation are analyzed versus the circuit parameters and the corresponding phase-shifts are calculated. The stability of the synchronized solutions is analyzed using the envelope transient simulation method. An 11.25-1.5-GHz down-converter with a 3.25-GHz free-running frequency has been designed, providing a phase-shift variation at intermediate frequency up to 540/spl deg/, with a 4.5-dB conversion gain. A good agreement between the simulated and experimental results has been found.     

Dual-Harmonic Noncontacting Millimeter Waveguide Backshorts: Theory, Design, and Test

Noncontacting backshorts are necessary in many applications to avoid the wear characteristic of contacting shorts. To reduce losses, it is desirable to eliminate the passband at second harmonic frequencies inherent in conventional quarter-wavelength designs. To this effect, empirically and theoretically designed shorts have been fabricated. The theoretical design extends low-frequency Chebyshev filter theory techniques for use at millimeter-wave frequencies. Both designs have been tested using swept frequency reflectometer techniques. Tests have been carried out over a 40-GHz bandwidth at 100 GHz and a 30-GHz bandwidth at 200 GHz. The results are superior to those obtained with Lambda/ 4 backshorts tested in the same manner.     

Optical generation of amplitude-equalized pulses from a rational harmonic mode-locked fiber laser incorporating an SOA loop modulator

Rational harmonic active and passive mode locking has been demonstrated in an erbium-doped fiber laser using an all-optical approach. Based on the modulation and the self-switching effects of a semiconductor optical amplifier nonlinear loop mirror, hybrid mode locking and pulse-amplitude equalization are simultaneously achieved in the laser. In our setup, amplitude-equalized pulse trains up to about 12 GHz are obtained at 1.55 /spl mu/m using 3-GHz optical driving pulses.     

Design parameters of a high-efficiency 1.7-GHz gyropeniotronamplifier

The feasibility of the gyropeniotron amplifier as a high-efficiency, high-power RF source to act as driver for accelerator in the 0.8-1.7-GHz frequency range is discussed. The klystrode is difficult to operate in this frequency range. Design parameters are given for a 1.7-GHz gyropeniotron operating with an axis-encircling beam (100 keV, 10 A) in a magnetron-type slotted waveguide. The external magnetic field required is 326 G. The calculated efficiency for second cyclotron harmonic operation is 78% with a cold beam and 66% with a beam having 2% axial velocity spread and 5% guiding center spread. The depressed collector technique can easily be applied to enhance the efficiency since the spent beam in a gyropeniotron has little velocity spread     

A low-voltage ultra-low-power translinear integrator for audiofilter applications

In this paper, the design and measurement of a l-V translinear integrator and its application in a controllable second-order lowpass filter for hearing instruments is presented. A semicustom version of the filter has been integrated in a standard 2-μm, 7-GHz, bipolar IC process and operates at voltages down to 1 V, consumes only 6 μA, and has a dynamic range of 57 dB for a total harmonic distortion below 2%. Its cutoff frequency is linearly adjustable in octaves from 1.6 to 8 kHz     

A Broad-Band, Ultra-Low-Noise Schottky Diode Receiver from 80 to 115 GHz Diode

A cryogenic 3-mm receiver has been developed which fully utilizes the low-noise potential of Schottky diodes by approaching the shot-noise limit within 10 percent. With a broad-band mixer design which properly terminates the input sidebands and reactively terminates the second harmonic of the local oscillator and its sidebands, the double sideband (DSB) mixer noise temperature is 35 K in the best case. This design has given an average DSB receiver noise temperature of 75 K over the 80 to 115-GHz band with a best noise temperature of 62 K.     

Triple-push oscillator approach: theory and experiments

This paper presents the theory and experiments of the triple-push oscillator approach. This oscillator architecture is combined with three identical oscillator subcircuits. An analytical mode analysis is used to describe the behavior of all modes. As will be shown, odd-mode currents in each oscillator subcircuit have a 120° phase shift to one another and thus produce in-phase combining for the third harmonic. The time domain analysis was performed to simulate a triple-push oscillator, showing that the phenomenon of 120° phase shift exists among each oscillator subcircuit. To prove this concept, a 4.9-GHz hybrid bipolar junction transistor (BJT) circuit and a 28.4-GHz heterojunction bipolar transistor (BJT) MMIC chip were demonstrated. The measured results showed that the 4.9-GHz BJT triple-push oscillator delivered an output power of 1.0 dBm at 4.9 GHz with 12.0-dB fundamental rejection, and the 28.4-GHz HBT MMIC chip exhibited a measured center frequency at 28.4 GHz with an output power of -15.4 dBm, while the output powers of the fundamental and the second harmonic signals were suppressed to -21 and -34 dBm     

Harmonic gain and noise in a frequency-doubling gyro-amplifier

Nonlinear gain in a 34-GHz three-stage frequency-doubling gyro-traveling wave tube (gyro-TWT) has been experimentally studied. The device consists of a thermionic electron gun, TE/sub 01//spl rarr/TE/sub 02/ fundamental gyro-TWT input section, second harmonic TE/sub 03/ intermediate buncher section, and a second harmonic TE/sub 02//spl rarr/TE/sub 04/ complex output circuit. Nonlinear bunching in the electron orbital phase generates harmonics of the input signal in the beam current, which excite the subsequent circuits at the second harmonic frequency. Since the gain is nonlinear, noise or applied sideband signals intermodulate with the carrier generating high-order products in the output. Therefore, it has been suggested that the noise figure of these devices may be unreasonably high. In this study, the complex harmonic transfer characteristics were experimentally measured and compared with calculations based on the assumption that the gyro-amplifier gain can be described, in the narrowband sense, as a classical frequency-doubling circuit. The results show that narrowband intermodulation gain is 6 dB higher than the carrier as predicted in the small signal limit, but as the device reaches saturation the nonlinear products become suppressed with respect to the carrier. Tests on the broadband gain characteristics show that output noise consists of second harmonic shot noise spontaneously excited in the output circuits along with the products of the intermodulation between external noise and the carrier. Good agreement between the experimental results and the calculations is demonstrated.     

Compact and Harmonic Suppression Wilkinson Power Divider With Short Circuit Anti-Coupled Line

A compact Wilkinson power divider using a short circuit anti-coupled line for harmonic suppression is presented in this letter. The structure consists of a pair of anti-coupled line short circuited by a capacitive load realized by a low impedance line. It can offer three finite attenuation poles in the stopband, while arbitrary phase shift can be obtained in the passband. Design procedures have been clearly presented. A 1.8-GHz power divider is designed, fabricated and measured for demonstration. It agreed well with the simulated results. The circuit area of the proposed divider is only 40% of that of the conventional one. Furthermore, the proposed divider has spurious pass-band suppression as high as 20dB.     

80-160-GHz mode-locked fiber ring laser synchronized to external optical pulse stream

The authors present a novel scheme to generate ultrahigh repetition rate picosecond pulses synchronized to an optical pulse stream in an actively mode-locked fiber ring laser. A monolithic Mach-Zehnder interferometer with integrated semiconductor optical amplifiers serves as an 80-GHz optically controlled modulator. 80-GHz transform-limited 2.1-ps Gaussian pulse with low timing jitter, extinction ratios up to 25 dB, and 5 mW of average output power are demonstrated. The laser is wavelength tunable over more than 15 nm around 1555 nm. At 160 GHz, 2.5-ps pulse trains with 3-mW output power are generated by rational harmonic mode locking.     

Stabilized Phase-Modulated Rational Harmonic Mode-Locking Soliton Fiber Laser

We realized the repetition rate multiplication in a phase-modulated soliton fiber laser with the rational harmonic mode-locking method. A modified pulse phase-locking method is used to stabilize the fiber laser at 10-GHz repetition rate with the rational harmonic order up to five (limited by the component performance). The laser showed an excellent stabilization performance in a long-term bit-error-rate test     

An experimental study of harmonic SIS mixing at 205-235 GHz

A 230-GHz subharmonically pumped waveguide mixer employing superconducting tunnel junctions has been developed. We present, in this paper, an experimental study of harmonic superconductor-insulator-superconductor (SIS) mixing at 230 GHz, focusing mainly on its noise behavior. The mixer has a double-tuned waveguide structure and employs an array of four 1.7-/spl mu/m/sup 2/ Nb-AlOx-Nb SIS junctions in series, with /spl omega/R/sub n/C/sub j//spl sim/3 at 230 GHz. Harmonic quantum mixing occurred over an experimental frequency range of 205-235 GHz (local oscillator: 112.5-117.5 GHz), exhibiting corresponding double sideband noise temperatures of lower than 150 K, with a lowest value of 75 K at /spl sim/230 GHz. The measured mixer noise is believed to be the lowest yet reported for a mixer using subharmonic-pump configuration at this frequency. A phenomenon that we attribute to the third harmonic SIS mixing has also been observed.     

Characteristics of dispersion-tuning in harmonically mode-lockedfiber laser

We investigate the characteristics of dispersion-tuning in an actively mode-locked fiber ring laser. A continuous tuning range over 20 nm at about 1-GHz operation is realized. The range can be extended by optimizing the polarization to attain a flattened spectral gain in the Er-doped fiber. The influence of the harmonic order of operation together with the amount of dispersion in the fiber ring have been experimentally studied. Rational harmonic mode-locking is first demonstrated in the dispersion-tuned laser to increase the output repetition rate. Our results agree well with theory, showing that dispersion-tuning is a reliable, economic, and effective way to generate widely tunable pulses     

Nonlinear optimization tools for the design of high-efficiency microwave oscillators

A new systematic method is presented for the design of high-efficiency microwave oscillators. It is based on the control of the transistor output-voltage waveform, through the combined use of a nonperturbing auxiliary generator and a substitution generator. The nonperturbing generator sets the oscillation frequency at the desired value during the entire design process. The combination of the two generators allows obtaining a quasisquare output-voltage waveform, with optimum harmonic components to maximize the efficiency. Attention is paid to the stability and phase noise of the implemented oscillator, which are analyzed versus technological parameters. A 6-GHz oscillator has been designed using these techniques, with good experimental results.