Abstract
In this work, on-chip single-to-balanced bandpass filters with good selectivity are proposed. The functions of bandpass filter and balun are integrated using a simple multicoupled line structure along with capacitive loadings. The use of inductor is avoided such that the proposed single-to-balanced bandpass filters can achieve very compact size when implemented on chip. They can be designed with the desired bandpass response and reference impedances through the proposed equivalent-circuit models and design equations. In addition, by introducing two cross-coupled capacitors, one tunable transmission zero can be achieved in either the lower or upper stopband to improve the selectivity. Specifically, two third-order single-to-balanced bandpass filter designs in commercial pHEMT process on 4-mil GaAs substrate with different transmission zero locations are presented. The circuit size is less than 1.02 mm × 0.86 mm for a center frequency of 5.5 GHz and a bandwidth of about 18.18%. The corresponding electrical size is only 0. 054λ g × 0.045λ g at the center frequency. Good selectivity and balanced performance are demonstrated.
Original language | English |
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Article number | 6075288 |
Pages (from-to) | 3322-3330 |
Number of pages | 9 |
Journal | IEEE Transactions on Microwave Theory and Techniques |
Volume | 59 |
Issue number | 12 PART 2 |
DOIs | |
State | Published - Dec 2011 |
Keywords
- Balun
- GaAs
- bandpass filter
- coupled-line
- transmission zero