Design Of High Selectivity IPD (Integrated Passive Device) LC Filters

The wireless systems today are convergent with multiple RF sub-systems integrated such as Bluetooth, WIFI, GPS and GSM. Integrating these technologies in a same device, in particularly in the “hand held” devices, we must realize the miniaturization of each functional module, as well as improve their capacity to the interference, so almost in all the RF front-end especially in the systems mentioned above there are key devices act as frequency selective devices—the RF filters. Thus it is important to improve the selectivity of the filters to reduce the effects of the interference from both the internal and external of the systems. Also, the BPF(bandpass filter) is one of the largest components in the RF front end, especially for the above mentioned applications. Therefore, reducing the size of the BPF can help the miniaturization of the overall system.The main work of this paper is studying the method of reducing the size and improving the selectivity of the filters, then design LC-IPD filters with small size form and high selectivity. The main content of this article is as follows:1.The basic resonate cells of the filters: series RLC resonator, parallel RLC resonator and transmission line resonators, the three types normal coupled resonator circuits :electric coupling, magnetic coupling and mixed coupling;2.The common structures to realize the generalized Chebyshev LC filters: adding extra components in the main or parallel resonance branches of the canonical Chebyshev LC filters, using the source-load cross-coupling and mixed-coupling between two neighbouring in the transformed Chebyshev LC filters;3.The usual structure to achieve the miniaturization of the microstrip filters :pseudo-interdigital line filters, meander open-loop filters, miniature filters with high dielectric constant substrates, combine SIW filter, microstrip LC filters and so on;4.The design of IPD-LC filters with high selectivity and small size: the brief introduction of the IPD process, the study of the effect of the design parameters on the property of the capacitor and inductor, the design and simulation of the IPD-LC filters with desired performance, the filters’ fabrication and measurement.