Total Noise Figure Research Articles

A 22-GHz-band low-noise down-converter for satellite broadcast receivers

A simple low-cost and high-performance 22 GHz band down-converter developed for a direct-to-home satellite broadcasting system is discussed. The down-converter consists of a low-noise high electron mobility transistor (HEMT) preamplifier, an image recovery mixer with a particular structure using dielectric resonator filters, a 21.4 GHz GaAs FET oscillator stabilized by a dielectric resonator, and an IF amplifier. These components are fully integrating using microwave integrated circuit technology into a small size. A total noise figure of less than 2.8 dB is obtained over the 22.5-23.0 GHz frequency range. The local oscillator achieves a frequency variation of less than 600 kHz/sub p-p/ over a temperature range of -20 degrees to +60 degrees C. >

A graphic design method for matched low-noise amplifiers

A graphic design method for matched low-noise amplifiers is presented in which all necessary design information is given in the load plane. It is possible to work exclusively in the load plane, as the input-matching requirement makes the source admittance dependent on the load admittance. As a consequence of the bilinear transformation involved, all parameters may be presented by circles. Analytic equations giving the centers and the radii of the circles in the load plane are presented. Two kinds of amplifier configurations are considered: a single-stage amplifier with an input-match requirement and a two-stage cascade amplifier. The latter is required to have an output match and noise-optimized second stage, in addition to an input match. For the single-stage case the noise figure, the power gain, the stability, and the input network are treated. In the cascade design, the total noise figure, the interstage network, and the available gain are treated as well. A design example for the case of lossless feedback is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Multimode resonant gravitational-wave antennas: How many modes is enough?

A model for multimode gravitational-wave antennas is presented. A complete sensitivity analysis is carried out for a simplified, but realistic degenerate case. We discuss the optimum configuration, proving that it is set by the two requirements that the last oscillator be light enough to achieve a sufficiently large energy coupling factor ..beta.. and the mass ratio ..mu.. satisfy a simple optimization condition. We show that the constraints imposed by current technology set an optimal number of modes. It is not advantageous to increase the degrees of freedom beyond this value, as this would add thermal noise to the total noise figure, without substantial gain in the efficiency of signal conversion.

Microwave Detector for Galactic Halo Axions

We discuss the properties and design characteristics of a dielectric tuned high-Q low temperature microwave cavity and cryogenic receiver for the detection of cosmic axions in the laboratory. The total noise figure and bandwidth properties achieved by a pilot project are discussed in terms of the feasibility of detecting axions trapped in the halo of our galaxy.

Analysis of Image Recovery Down Converter Made by Planar Circuit Mounted in a Waveguide

This paper presents an analysis of a superhigh frequency (SHF) down converter using a Schottky-barrier mixer diode and a planar circuit mounted in a waveguide. The analysis assumes that the mixer diode consists of a nonlinear conductance g, a junction capacitance C/sub j/, an ohmic spreading resistance R/sub s/, and several parasitic susceptances. The frequency performance of the impedance of external circuits at the signal, image, and intermediate frequency bands is considered. This analysis also includes consideration of the mismatching effect between the converter and the IF amplifier, and the optimum design procedure for the down converter. Using this theoretical method, a SHF down converter was designed and constructed. Its application is low noise receivers for satellite broadcasting. The design used the optimum image condition (the image impedance takes a low value, i.e., nearly a short). The RF band is 11.7 - 12.2 GHz, the IF band is 0.96 - 1.46 GHz, and the total noise figure is 3.3 - 3.7 dB. The noise figure is in good agreement with the (3.2 - 3.6 dB) obtained from this analysis.

A 26-GHz Band Integrated Circuit of a Double-Balanced Mixer and Circulators

Integration of a double-balanced mixer and ferrite-disk type circulators have been successfully achieved in the 26-GHz band. The total single-sideband noise figure of the integrated circuit, composed of a mixer and two circulators, is 8.5 dB, including the noise contribution from an IF amplifier. The double-balanced mixer is composed of microstrip lines, slot lines, coupled slot lines, coplanar lines, Au wires, and four beam lead Schottky-barrier diodes. The minimum conversion loss of the mixer is 5.3 dB at a signal frequency of 25.4 GHz. Isolation between RF and LO ports is greater than 30 dB. The ferrite-disk type circulator is produced by a newly developed precise machining technique. The minimum insertion loss of the circulator is 0.45 dB, and the isolation is greater than 20 dB. The integrated circuit with the ferrite-disk type circulators will be extended to the millimeter-wave band.

Millimeter-Wave Thin-Film Downconverter

A 60-GHs hyhrid integrated downconverter intended for use in a mitlimeter-wave radio relay experiment has heen designed and tested. The converter consists of a strip transmission line circuit and two beam-leaded Schottky-barrier diodes which are pumped at a subharmonic of the convectional Iocal oscillator frequency. The conversion loss of the circuit is 6.3 dB and the total single-sideband noise figure, including the noise contribution from the IF amplifier, is 9.1 dB. The circuit looks attractive for millimeter-wave communication systems application up to 100 GHz.