Bandpass filters are key components in RF/microwave communication systems. As the system goes smaller and lighter, size reduction becomes more and more important. In addition, impedance matching and high performance is also crucial to a communication system. Thus, a two-stage bandpass filter with both small size and automatically matching is more desirable.
In this thesis, a novel miniaturized CMOS bandpass filter will be introduced. It is based on the structure of diagonally short-ended coupled line with loaded capacitors for size reduction and using multilayer conductors for high quality factor. In this structure, the ground plane is capsulated around the filter, which enables it avoid the coupling to other basic components in the transceiver system. In addition, as another major advantage, it was proven to have an impedance matching automatically. The greater difference between the simulation and measurement in CMOS fabrication is also analysed and it will be proven to be caused by transmission losses and quality factors in the lossy distributed inductor of shunt resonator.
Design equations and method will be fully explained in this thesis. A lot of simulated results and measured results are also presented. The method of enhancing the performance of the bandpass filters and automatically impedance matching will be described. Four kinds of circuits which based on the MagnaChip 0.18μm process are fabricated. Many simulated and measured data are collected and provided here to show the advantages of the proposed bandpass filter.