Abstract
This paper presents the analysis of tuning range and power handling of digitally tunable capacitors (DTCs) in reconfigurable high power RF circuits. The proposed scheme can be applied to reconfigurable RF system design e.g. smart antenna, Software Defined Radio (SDR) and Cognitive Radio (CR) systems. The power handling of the DTC can be enhanced by connecting the DTC in series with a fixed capacitor. The combination of a DTC and a fixed capacitor leads to modified tuning range of the total capacitance. Both the power handling and the tuning range are described in this paper by empirical equations in such a way, that a proper combination of DTCs and fixed capacitors can be determined for the design of any reconfigurable RF system. As an example of applications, a frequency band reconfigurable power amplifier was designed and fabricated. The reconfigurable input and output matching networks utilize DTCs and fixed capacitors as tuning elements.
