Design of a microstrip dual‐band filter with modified short‐circuit quarter‐wavelength resonators

Abstract

characteristic of a SBM. Figure 11 shows the measured LO/IF isolation. As can be seen, a better than À40 dB isolation is achieved across the UWB frequency. The LO/RF and RF/IF isolations are also better than À40 dB. The total power consumption is 29.1 mW from a 1.8 V power supply. Table 1 summarizes the measured results and the previous reports on UWB RF receiver [2,[5][6][7]. CONCLUSIONSUWB RF receiver using 0.18-lm CMOS technology is presented, which includes an LNA and a SBM. The inter-stage inductor is used to combine with the RC shunt feedback LNA for broadening the bandwidth up to 10 GHz. Furthermore, the lowpass IF load and RC shunt feedback techniques are used in the IF and g m stages of mixer. These techniques not only flattens the power gain, including the entire bandwidth, but also provides the high LO/IF isolation of UWB RF receiver. As this integrated receiver has an overall good RF performance with low power consumption and compact chip area, it will find many applications in UWB RF transceiver. ACKNOWLEDGMENTSThis article is partially supported by National Science Council of the Republic of China under Contract No. NSC97-2628-E-008-001-MY3. National Chip Implementation Center (CIC) and TSMC for chip fabrication are also acknowledged. ABSTRACT: A dual-band microstrip bandpass filter is proposed. With the assistance of modified short-circuit quarter-wavelength resonators, the dual-band bandpass filter can be developed. Theoretical analysis and design procedures are provided; the prototypical bandpass filter with dual passbands is fabricated and measured as well. Well-matched simulated results and experimental data validate the proposed filter.