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Abstract-A varactor diode configuration is presented for the implementation of low-distortion tunable matching networks, phase shifters, and filters. The configuration is based on varactors with an "exponential" ( ) relation in antiseries configuration with specific control voltage harmonic loading conditions. The resulting network combines a high capacitance tuning range with relatively low control voltages and excellent linearity. The linearity is independent of the applied control voltage and does not degrade at low tone spacing, which is ideal for the realization of adaptive transmitters and modulators. A specific 2 varactor doping profile is required for exact third-order intermodulation (IM3) cancellation. The remaining distortion is dominated by the much smaller fifth-order nonlinearities. The required impedance levels of the harmonic terminations are studied in terms of the maximum modulation bandwidth for which the proposed configuration remains linear. The doping profile optimization for quality factor, tuning range, and breakdown voltage is discussed. For experimental verification, the proposed varactor configuration has been implemented using a silicon-on-glass technology. The measurements demonstrate IM3 cancellation and indicate a superior linearity for modulated signals up to 10-MHz bandwidth.

A simulation of an optically pumped laser based on a ZnSe/ Zn 1−y Cd y Se double quantum well with a Zn 1−x Mn x Se diluted magnetic semiconductor barrier is presented. Giant Zeeman splitting in diluted magnetic semiconductors leads to splitting of electronic states, which in turn leads to tunability of laser wavelength by external magnetic field. Tunability is predicted throughout the wavelength range between 60 and 72 m at low temperatures.

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