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Source publication
Tunable capacitors can be used to facilitate the reduction of components in wireless technologies. The tunability of the capacitors is caused by the sensitivity of the relative
dielectric constant to a change in polarization with electric field.
Thin film ferroelectric MIM capacitors on silicon offer a re-use of electronic circuitry, low tuning vol...
Contexts in source publication
Context 1
... tunable capacitor with a (Ba,Sr)TiO 3 dielectric can operate typically in two phase regions. The operating region depends on the temperature, and the composition of the ferroelectric material. The effect on the relative dielectric constant is indicated in fig. 1. The latter two points in the table are known as the performance parameters of a tunable capacitor. The tunability n, expressed in eq.1, defines the amount of capacitance tuning from zero DC voltage until a specific voltage (lower than the breakdown ...
Context 2
... curve A typical C s -V dc is measured from zero DC voltage in steps of 2 V until breakdown at both sides with the VNA and a DC voltage source. The C s -V dc curve in fig. 10 is almost symmetric for positive and negative voltages. The capacitance and tunability decrease with frequency in the RF range due to distributed effects as explained ...
Citations
... Examples of tunable electronic components are tunable MEMS inductor [1] and tunable capacitor technologies, e.g. RF MEMS [2], varactor diodes [3] and ferroelectric capacitors [4]. We optimize tunable ferroelectric capacitors on silicon for integration into microwave frequency agile applications that could comprise of e.g. ...
To analyze the intrinsic dielectric performance of planar high-density capacitors at radio frequencies (RF), the dielectric losses need to be distinguished from the resistive electrode losses. The resistive losses of the electrodes at RF are de-embedded employing a linear regression procedure with partial compensation for distributed effects. We use tunable ferroelectric capacitors with a barium strontium titanate (BST) dielectric with an inner diameter d ≥ 8 μm on a silicon substrate. The de-embedding of the electrode losses has been successfully performed utilizing 1-Port RF measurement data from of an Advantest R3767CG vector network analyzer (VNA) in the frequency range of 10 MHz – 8 GHz.
Measured capacitance vs. voltage data along with measured 3rd-order intermodulation distortion (IMD) data at various bias and temperatures are presented for interdigital barium strontium titanate varactors. A dip/sweet spot is observed in the 3rd-order intermodulation distortion products when plotted vs. input RF power. The dips occur at RF power levels near 20 dBm and are an important consideration for large signal applications of BST varactors. Shifts in the dip are reported as the bias voltage is varied from 0-50V. Non-linear modeling methods are also discussed.
In this thesis, the results of intensive electrical characterization, modeling and the design of hardware with thin film tunable capacitors, i.e., dielectric varactors, has been presented and discussed. Especially the quality factor Q and the tuning ratio of the tunable capacitors have been studied, since these are crucial parameters for reconfigurable RF front-end applications for mobile phones.
