__Keywords:__CAD designing element model equivalent scheme chip- inductor coil chip- capacitor Microwave Office MWO S-parameters

S. A. Babun’ko, V. A. Bazhilov, Yu. G. Belov

There are several variants of chip-elements equivalent schemes, differring on degree of the correspondence a features of models and real element (the degree of models validity). However for the most reliable models finding the values its parameter for concrete element is a complex problem. A parameters, provided in reference book and mortgaged in model CAD, do not coincide. Actual is a problem of the choice of the most reliable models from number known (or designing of the more making new models) and creation a libraries of parameters for these models. Results of decision this problem for chip-element the most wide-spread sizes (0603 and 0805) are presented in persisting work. The decision second, more labour-consuming part of problem was produced by means of toolbox software package MWO on base of the information on chip-elements parameters, brought by producers.
The most reliable for chip-inductances, on our glance, is an equivalent scheme, designed by Coilcraft Company. Equal nominal impor-tance of the inductance element in model is taken value L. The resistor R2 characterizes the Ohmic resistance of the inductor wire, C – interwinding capacity. For account of dependencies the resistance conductor from frequency in consequence of skin-effect in model aside from R2 is incorporated resistor Rvar, which resistance is defined on formula , where k – a factor, definied design of the spool and material of the conductor, f – a work frequency. The resistor R1 defines losses in spool in consequence of radiation, dissipations of the magnetic field and drain through base material. A calculation results for clarity are presented in the manner of graph, on which can be definite sign parameter of chip-inductor model with concrete nominal value of the inductances L.
At modeling neither one of proposed in the known CAD models chip-capacitor nor allow it is enough exactly to value the features a chip-element in broad range of frequencies. A new model chip-capacitor is offered in this connection. In brought scheme is marked: C1 -a capacity of the capacitor (is taken equal nominal); L1 -an inductance of the internal structure of capacitor; R1 -a resistance, taking into account Ohmic loss in coats of capacitor and loss on radiation; L2 – outputs inductance; C2 – interoutput capacity; R2 – a resistance, characterizing dielectric losses; R3 – a resistance, characterizing drain between outputs of the capacitor through air.
In the same way, either as in model chip- inductor coil, in chip-capacitor model one of the element, characterizing losses, necessary to consider variable (hanging from frequency). Such element in model is a resistor R1. This parameter is presented in the manner of . In this formula – a resistance for chip-capacitor by capacity 1 pF (the least nominal value), which is a function of the frequency, K>1 – a factor, having different importances for miscellaneous nominal value to capacities.
At development microwave bandpass filters on chip-elements the validity offered models was confirmed by experimental studies. There were modeling and are made different bandpass filters with different frequency feature. On the base of comparisons of the measured features made filters and results of modeling possible to draw a conclusion about high degree of models validity and possibility of their using in condition of the real designing.
Use the specified element models advantageously differ from direct use brought producers S-parameters that with model possible to work in mode of the automatic optimization of the features under development device. Also available modes of manual tuner and determination of features behaviour when entering the tolerance on nominal values element (the Yield Optimization procedure). The use S-parameter element does not give such possibilities.

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