Designing an active band-pass filter with tunable transversal element at 4-GHz using 0.2µm GaAs technology

Nowadays, 4-GHz band-pass filters become important for several fields of applications such as Bluetooth, wireless LAN (WLAN), RFIDs, and etc. The growing requests for ultra integration of small mobile communication leads the designs to more wireless applications (wireless network, mobile, and etc). A transceiver system needs to design a filter that properly provides its requirements. The filter reported in this paper uses lumped elements to achieve a basic band-pass filter response. Active transversal elements are used to sharpen the band-pass characteristics, and to overcome the losses of MMIC lumped elements. In addition, the combination of lumped and transversal elements provide much better performance compare to a filter made of lumped elements alone, and much smaller than a filter made of transversal elements alone. A GaAs MMIC active band-pass filter structure is proposed for operation in the S-band applications and GaAs MMICs applications for wireless personal communication are described. This filter centered at 4-GHz and has 30 dB rejections at 0.7-GHz apart from pass-band edges. These sharpened edges were caused by a tuned amplifier.