TY - JOUR
T1 - Ultra-compact (80 mm 2) differential-mode ultra-wideband (UWB) bandpass filters with common-mode noise suppression
AU - Velez, Paris
AU - Naqui, Jordi
AU - Fernandez-Prieto, Armando
AU - Bonache, Jordi
AU - Mata-Contreras, Javier
AU - Martel, Jesus
AU - Medina, Francisco
AU - Martin, Ferran
PY - 2015/4/1
Y1 - 2015/4/1
N2 - © 2015 IEEE. This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) bandpass filters with common-mode noise suppression. To a first-order approximation, the differential-mode filter response is described by the canonical circuit model of a bandpass filter, i.e., a cascade of series-connected resonators alternating with shunt-connected parallel resonant tanks. Thus, the series branches of the balanced filter are implemented by means of inductive strips and patch capacitors, whereas the shunt sections are realized through mirrored stepped-impedance resonators (SIRs) and low-impedance (i.e., capacitive) short transmission-line sections. For the differential mode, the symmetry plane is a virtual ground, the wide strip sections of the SIRs are effectively grounded, and the SIRs behave as grounded inductors parallel connected to capacitors. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIRs act as shunt-connected series resonators, thus providing transmission zeros at their resonance frequencies. By properly tailoring the location of these transmission zeros, rejection of the common mode over the differential filter passband can be achieved. To illustrate the potential of the approach, an order-5 balanced bandpass filter covering the regulated band for UWB communications (3.1-10.6 GHz) is designed and fabricated. The filter exhibits common-mode rejection above 10 dB over the whole differential filter passband, with differential-mode insertion losses lower than 1.9 dB and return losses better than 10 dB. Since the proposed design approach is based on planar semi-lumped components, filter size is as small as 10.5 mm ×\, 7.6 mm.
AB - © 2015 IEEE. This paper presents a novel approach for the implementation of balanced ultra-wideband (UWB) bandpass filters with common-mode noise suppression. To a first-order approximation, the differential-mode filter response is described by the canonical circuit model of a bandpass filter, i.e., a cascade of series-connected resonators alternating with shunt-connected parallel resonant tanks. Thus, the series branches of the balanced filter are implemented by means of inductive strips and patch capacitors, whereas the shunt sections are realized through mirrored stepped-impedance resonators (SIRs) and low-impedance (i.e., capacitive) short transmission-line sections. For the differential mode, the symmetry plane is a virtual ground, the wide strip sections of the SIRs are effectively grounded, and the SIRs behave as grounded inductors parallel connected to capacitors. However, for the common mode, where the symmetry plane is an open (magnetic wall), the SIRs act as shunt-connected series resonators, thus providing transmission zeros at their resonance frequencies. By properly tailoring the location of these transmission zeros, rejection of the common mode over the differential filter passband can be achieved. To illustrate the potential of the approach, an order-5 balanced bandpass filter covering the regulated band for UWB communications (3.1-10.6 GHz) is designed and fabricated. The filter exhibits common-mode rejection above 10 dB over the whole differential filter passband, with differential-mode insertion losses lower than 1.9 dB and return losses better than 10 dB. Since the proposed design approach is based on planar semi-lumped components, filter size is as small as 10.5 mm ×\, 7.6 mm.
KW - Common-mode suppression
KW - differential filters
KW - microstrip technology
KW - stepped-impedance resonator (SIR)
KW - ultra-wideband (UWB)
U2 - https://doi.org/10.1109/TMTT.2015.2401555
DO - https://doi.org/10.1109/TMTT.2015.2401555
M3 - Article
VL - 63
SP - 1272
EP - 1280
JO - IEEE Transactions on Microwave Theory and Techniques
JF - IEEE Transactions on Microwave Theory and Techniques
SN - 0018-9480
IS - 4
M1 - 7046445
ER -