Spectrum analyzer

About: Spectrum analyzer is a research topic. Over the lifetime, 12217 publications have been published within this topic receiving 101851 citations.

A Vector Corrected High Power On-Wafer Measurement System with a Frequency Range for the Higher Harmomcs up to 40 GHz

Abstract: A high power on-wafer measurement system based on the new microwave transition analyzer (MTA) HP 71500A has been developed for the complete characterization of the large signal behavior of transistors. One key feature of the MTA based measurement system is that during power sweeps the harmonic behavior, up to 40 GHz, can be measured. To improve the accuracy of power measurements the vector measurement capability of the MTA is also utilized to allow full vector calibration of the measurement system. In addition, this vector measurement feature allows both the input reflection and the transmission coefficients of a device under test (DUT) to be measured as a function of frequency and input power. The input and output voltage waveforms at the transistor terminals are also calculated from the measurement data. This improved capability is possible since the vector calibrated measurement system allows both the measurement of the fundamental and the higher harmonics with respect to magnitude and phase.

Application of a Differential Fuel-Cell Analyzer for Measuring Atmospheric Oxygen Variations

Abstract: A commercially available differential fuel-cell analyzer has been adapted to make field-based ppm-level measurements of atmospheric O2 variations. With the implementation of rapid calibrations and active pressure and flow control, the analysis system described here has a 1σ precision of ±2.5 per meg (≈0.5 ppm) for a 2-min measurement. Allowing for system stabilization after switching inlet lines, a 6-min measurement with a precision of ±1.4 per meg (≈0.3 ppm) every 20 min is obtained. The elimination of biases in any atmospheric O2 measurement depends critically on careful gas-handling procedures, and after screening for known sources of bias a comparability of ±10 per meg (≈2 ppm) with the present setup is estimated. In comparison to existing techniques, the relatively small size, low cost, fast response, motion insensitivity, and ease of implementation of the fuel-cell analyzer make it particularly useful for a wide range of unattended field applications. This system has been used to measure at...

Pulsed plasma source spectrometry in the 80--8000-eV x-ray region

Abstract: The general characteristics are compared for the plane, convex, and concave fixed crystal analyzers which may be applied to the spectrometry of concentrated, intense plasma sources of x radiation involved, for example, in fusion energy and x‐ray laser research. The unique advantages of the elliptical analyzer for precise and absolute spectral measurements are noted and detailed descriptions of its geometrical and physical optics are presented. With a source point at one of the foci of the elliptical analyzer profile, the spectrum is Bragg reflected (45°<2θ<135°) at normal incidence upon a detection circle with its center at the second focal point, at which an effective scatter aperture and filter window is located. A primary monochromator consisting of a cylindrical, grazing‐incidence mirror is placed between the source and the analyzer to provide an efficient cutoff for high‐order diffracted background radiation and to focus the divergent rays so as to obtain an adjustable spectral line length at the detection circle. Photographic film may be transported along the detection circle. Linear position‐sensitive electronic detection arrays or a streak camera slit window may be placed along a chord of the detection circle. Calibration procedures for absolute line and continuum intensity measurement are described and examples of calibrating spectra are presented as measured with elliptical analyzers of LiF, PET, KAP, and molecular multilayers for the 80–8000‐eV photon energy region. The instrumental effects that contribute to the spectral line shape as measured by the elliptical analyzer spectrograph are defined and a simple line‐shape analysis procedure is presented for the determination of the line‐broadening contributions of the source. The effects of an off‐axis positioning of a source point and of an extended source are analyzed and the application of the elliptical analyzer spectrograph for one‐ and two‐dimensional imaging or an extended source at a given photon energy is discussed. Finally, methods and materials for the construction of the elliptical analyzers are described.

Chirping characteristic and frequency response of MQW optical intensity modulator

Abstract: The spectral linewidth enhancement factor and frequency responses of electro-absorption-type optical-intensity modulators, especially InGaAs/InAlAs MQW modulators, are described. A method of exactly estimating the value of the alpha factor is presented under the nonlinearity of extinction-ratio characteristics. For measuring the frequency response of modulators, the sideband strength of the modulated output light with an optical spectrum analyzer, is analytically compared with the microwave power of photodiode direct detection with an electrical spectrum analyzer. >