Electronically Tunable Transmission Zeros Bandpass Filter with Notch Response

This paper presents a design of tunable transmission zeros bandpass filter with a notched response in a single device. The bandpass filter is designed using 7
^th
order short circuited stub filter. Then, the first short circuited stub is replaced with two sections of open circuited stub to exhibit the transmission zeros at lower/higher stopband. The varactor diode is placed at the J-shape open circuited stub to produce tunable transmission zeros by tuning the voltage on the varactor diodes with range from 0 V to 6 V. The U-shape notched response produced high selectivity and attenuation at resonant frequency of 5.2 GHz. The fabricated result shows good agreement with the simulated results. This type of filter is very useful for applications where the undesired signals and interference will be eliminated within the passband response such as medical electronic, radar and 5G applications.