Highly linear microstrip wideband bandpass filter with switchable notched band for wireless applications

This article presents a highly linear reconfigurable bandpass filter embedded with a switchable notch structure to get a band-notched characteristic at a specified frequency.A single PIN diode (BAP65-02) is used for the purpose of switching the notch. An optical switch, comprised of a silicon dice activated using near infrared light is also investigated as an alternative to the PIN diode. While the PIN diode or the optical switch is in the ON state this reconfigurable filter behaves as a bandpass filter with a notch at 2.4 GHz in order to reject WLAN interference while a full band response is obtained in the OFF state. The proposed filter is able to achieve good linearity using PIN diode with IIP3 of 47 dBm and there is no significant loss. A prototype is fabricated, and measured results are compared to simulations. A good agreement has been achieved between simulated and measured results.