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Using synchronously controlled varactor tunable oscillators into both the RF and LO ports of a mixer produces a resulting VCO output which is extremely linear and wideband. A deviation from best straight line of +-25MHz has been achieved over a frequency range of 2-8GHz, tunable in only 4.77V. This high modulation sensitivity is accompanied by a fast set-on time of < 20ns.
The design of Q band IMPATT diode cavity combiners is discussed. The design is based on a three-step closed form algorithm. The first step is the characterization of the passive circuit (cavity and diode package) using an automatic network analyzer. In the second step, a computer program is used to generate diode device lines. The third step is the load line synthesis for predictable operation as...
A GaAs FET regenerative frequency divider operating at K/sub u/-band is described, employing a 0.5 µm gate length device biased in the vicinity of pinch-off so as to provide both the gain and the nonlinear properties required for achieving frequency division. The study includes measured circuit responses as functions of drive level for single-tone CW, single-tone pulsed, and two-tone CW excitations.
This paper describes design and realisation criteria for linear power amplifiers used in novel 16 QAM radio link systems. The 6.4-7.1 GHz amplifiers use 6 cascaded stages and perform a .9 W mean output power with a 42 dB linear gain and -37 dBc 3rd order IM. The 10.7-11.7 GHz version uses 8 cascaded stages to perform a .5 W mean output power with the same distortion value.
A basic theory for broadband balanced frequency-halving circuits is presented. The analysis is applicable to both Schottky-barrier and reverse-biased abrupt-junction varactors and is based on the solution of exact nonlinear differential equations. An approximate algebraic method yields the global steady-state amplitude and phase solutions, while numerical integration gives transient solutions under...
The development of a 20 GHz proof-of-concept (POC) high power solid state transmitter sponsored by NASA Lewis Research Center and USAF Space Division is described. The transmitter utilizes GaAs INPATT diodes for high power output and high efficiency, and operates in the constant-voltage injection-locked mode to achieve high dc-to-rf conversion efficiency. The transmitter is a three-stage design consisting...
A phase modulator circuit is described showing improved broadband capability. A phase error less than 2° can be achieved over more than 25% bandwidth. Circuit realizations in microstrip, fin-line and waveguide technique are also presented.
Direct measurement of principal characteristics of a negative resistance nonlinear M. I. C. Oscillater using a network analyser is presented. Theoretical considerations and experimental results are shown for the injection locking polar diagram obtained by placing the oscillator directly at the unknown port without the use of a circulator.
Experimental results are presented which demonstrate that IMPATT diode preselection by growth wafer is unnecessary in order to achieve good power combining efficiency. With the possible exception of junction capacitance, tight tolerances (<+-10%) on DC or RF characteristics are also found to be unnecessary.
GaAs PIN diode material with low forward resistance and high Q reverse bias capacitance has been successfully grown for the first time. Static performance data for shunt mounted chips in a microstrip SPST switch show improved insertion loss for the 2-40 GHz range. Dynamic data show switching speed and switch drive power advantages of GaAs over Si for both carrier injection and sweep-out modes of operation.
A broadband, universal transistor test fixture uses exchangeable inserts to accommodate most transistor types. The calibration of the fixture and its inserts by a reliable, accurate and easy to use scheme is described.
Quatenary dielectric waveguide systems, which could be applied to optical fibers and dielectric image lines, are analyzed with an extended point-matching method. Theoretical results are confirmed with microwave experiments.
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