Compact Dual Band LowPass-BandPass Filter

This paper presents the design of a compact dual band lowpass-bandpass filter (LPF-BPF) for GSM applications. The idea behind this design is to apply multiple miniaturization techniques on the dual band to achieve compact dimensions with optimal performance. Miniaturization is achieved by using lumped capacitors along with DGS and meandering techniques. The designed filter shows dual behavior: lowpass behavior with cutoff frequency at 0.9 GHz and bandpass behavior with center frequency at 2.4 GHz. The achieved size reduction when applying the three miniaturization techniques is 70%. Measurement results validate the proposed design. Moreover, the design is also compatible with integrated circuit process.