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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
City-block distance is a special case of Minkowski distance when = 1. See also Minkowski distance. cladding the optical material that concentrically surrounds the fiber core and provides optical insulation and protection for the core. The refractive index of the cladding must be lower than that of the core material so that optical power is guided through the fiber by total internal reflection at the core-cladding boundary. See also total internal reflection, Snell's law. clamping the process of fixing either the minima or maxima of a voltage. Clapp oscillator an oscillator whose frequency is determined by a tuned parallel LC circuit with a split capacitance, i.e., two series capacitances, in the capacitive branch and an additional series tuning capacitance in the inductive branch. The Clapp oscillator is a variation of the Colpitts oscillator. class (1) in general, patterns are commonly discriminated into different categories according to certain properties they share. The categories in which a given set of patterns are partitioned are referred to as classes. (2) in object orientation, is an entity that defines a set of objects which share the same attributes and processes. class fuse See U.L. classes.
Added Noise in Oscillators Caused by the Transistor Base Emitter Breakdown Phenomenon
Published in IETE Journal of Research, 2023
Wolfgang Griebel, Matthias Rudolph, Ulrich L. Rohde
In the course of a Ph.D. thesis to determine and improve the short term frequency stability in the range from one to fifteen seconds, detailed examinations of space-grade ultra-stable oscillators (USOs) in the 5 MHz range were carried out to determine the optimum bias conditions for low noise operation of a Clapp oscillator (a variant of the Colpitts oscillator where the inductor is replaced by a series combination of an LC circuit, here a crystal resonator [1]). These tests were taken at a series of operating points at various collector voltages and base bias conditions, and for every combination an automatic test system recorded all DC parameters (supply voltages, currents, …), all waveforms and phase noise data. While in some regions of moderate bias, the measurements agreed reasonably well with the classic oscillator theory, high bias resulted in an abnormal degradation of phase noise despite a measured increase of the power output. An in-depth analysis showed that the unwanted BE (Base-Emitter) junction breakdown was responsible for the added noise. Phase noise dependence on bias conditions for HEMT and HBT semiconductors was analyzed in [2,3].