1. A Differential-Mode Wideband Bandpass Filter on Microstrip Line for UWB Application
TeckBeng Lim and Lei Zhu, Senior Member, IEEEIEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, VOL. 19, NO. 10, OCTOBER 2009
Presenters:
Kate Momsen
Sean Morgan
2. Introduction
Ultra Wideband (UWB) Filters used in wideband communication systems
Most of previous work has created non-differential-mode (DM) wideband filters
Previous DM filters do not have good common-mode (CM) suppression
CM suppression necessary for circuitry with common grounds (e.g. amplifiers)
3. Transmission Line Implementation of UWB Filter
Port 1
Port 1
Port 2
Port 2
T-Line System
DM Setup
T-Line System
CM Setup
Term
Term
Port 1
Port 1
Port 2
Port 2
Term
Term
4. Varying Design Parameter of T-Line Implementation
System Specs:
Z1 = 30.1
Z2 = 24.1
Z12 = 49
ZA = 100
Line Length:g/4
5. Microstrip Line Implementation-Full Wave Simulations

LA stub is split and wrapped to save space 6. Substrate Thickness: 0.635 nm 7. Relative Dielectric: 10.8

Fullwave simulation resultsclosely match those for the simulated transmission line implementation
8. Microstrip Implementation on RT/Duroid 6010
Fabricated UWB Filter

Passband range of 2.7 5.3 GHz with a fractional bandwidth of 65% 9. 20 dB common-mode rejection shown with simulations and through experimentation

Comparison of fullwave simulation and experimental results using fabricated design over frequency range of 1 to 8 GHz
10. Conclusions
Wideband DM bandpass filter designed and fabricated on microstrip
65% DM fractional bandwidth while maintaining 20 dB rejection in CM
Theory of model developed using simulations on ideal transmission lines
Final microstrip design tested and optimized using fullwave simulator