Realization of a wideband bandpass filter using cascaded lowpass to highpass filter

This paper presents a wideband bandpass filter design, achieved by cascading a lowpass filter and a highpass filter. The lowpass filter is designed using L-C-ladder network, where relatively high impedance line is used to realize series inductor and low impedance line is used to realize shunt capacitor. For highpass filter, high impedance inductor line is grounded using metallic via and series capacitor is realized using inter-digital fingers structure. The lowpass and highpass filters are designed separately. These filters are then cascaded to obtain a wideband bandpass response with the passband ranges from 2.12 GHz to 4.06 GHz and a center frequency of 2.94 GHz. The filter has a pass-bandwidth of 66%. The simulated results show passband insertion loss of less than 1.6 dB. The measured results show good agreement with theoretical results.