Yujia Peng

High performance tunable slow wave elements enabled with nano-patterned permalloy thin film for compact radio frequency applications

Slow wave elements are promising structures to design compact RF (radio frequency) and mmwave components. This paper reports a comparative study on different types of coplanar wave-guide (CPW) slow wave structures (SWS). New techniques including the use of defected ground structure and the different signal conductor shape have been implemented to achieve higher slow wave effect with comparative loss. Results show that over 42% and 35% reduction in length is reported in the expense of only 0.3 dB and 0.1 dB insertion loss, respectively, which can end up with 66% and 58% area reduction for the design of a branch line coupler. Implementation of the sub micrometer patterned Permalloy (Py) thin film on top of the simple SWS has been demonstrated for the first time to increase the slow wave effect. Comparing with the traditional slow wave structure, with 100 nm thick Py patterns, the inductance per unit length of the SWS has been increased from 879 nH/m to 963 nH/m. The slow wave effect of the designed structur...

Performance enhanced miniaturized and electrically tunable patch antenna with patterned permalloy based magneto-dielectric substrate

Perspective magneto-dielectric materials with high permeability are potential substrates to miniaturize the patch antenna without deteriorating its performance. Besides its high permeability at high frequency, patterned Permalloy (Py) also presents tunable permeability by applying DC current. A performance enhanced miniaturized and electrically tunable patch antenna with patterned Py thin film is first presented and developed in this paper. To suppress the magnetic loss, the Py thin film layer is consisted of an array of 2 μm × 2 μm square Py patterns between the copper patch antenna and dielectric substrate. The DC current could be applied directly on Py patterns through the copper strip lines beneath the Py patterns along the length of patch antenna. The copper strip lines are specially designed with the same width of Py patterns and the thickness much less than the skin depth at the operating frequency, which can reduce their deteriorating effects to the performance of antenna. The structure of the ant...

Direct current tunable noise suppressor using sub-micrometer patterned permalloy films

A tunable noise suppressor at gigahertz frequency using sub-micrometer patterned Permalloy (Py) loaded coplanar waveguide transmission line is presented. The transmission line consists of 100 nm thick Py patterns on top of 0.9 μm thick gold lines. Measured results show that the stop band frequency of the noise suppressor is changed from 4.8 GHz to 6 GHz depending on the aspect ratios of Py patterns. Variation of the gap in between Py patterns changed the stop band frequency from 4 GHz to 6 GHz. Furthermore, a novel way of tuning the stop band frequency of the noise suppressor by using an external direct current is reported. By applying 150 mA direct current along the transmission line, the frequency is changed from 6 GHz to 4.3 GHz. The measured results of 1.5% pass band loss, 2° transmitted signal phase distortion, and 3 dB extra return loss of the designed noise suppressor are demonstrated. Noise suppression frequency and the magnitude of signal attenuation can be further improved by increasing the thic...

Compact Dual-Band Filter Using Open/Short Stub Loaded Stepped Impedance Resonators (OSLSIRs/SSLSIRs)

A novel microstrip dual-band filter with high frequency selectivity and extended rejection band is reported in this letter. The proposed filter employs one pair of open stub loaded stepped impedance resonators (OSLSIRs) functioning at two frequencies of interest. Two short stub loaded stepped impedance resonators (SSLSIRs) are embedded between the coupled OSLSIRs to generate quasi-elliptic response at two diverse frequencies. Contributed by the 0° feed structure, extra transmission zeros are produced to enhance the out-of-band rejection. OSLSIRs/SSLSIRs are chosen to achieve desired in-band performance and misaligned harmonic frequencies simultaneously. To demonstrate the efficacy of the design concept, a dual-band filter centering at 1.63 and 2.73 GHz is implemented. The design methodology and measured results are presented.

Engineered smart substrate with embedded patterned permalloy thin film for radio frequency applications

Multifunctional and frequency-agile devices are promising components that satisfy multiple standards of modern wireless communication system. This paper provides a unique method to develop tunable RF components based on engineered smart substrate where the smart substrate contain patterned Permalloy (Py) thin film on high-resistivity silicon. The permeability of Py can be adjusted by changing the DC current, thus allowing tunable RF circuits and components. Single or multi-layer patterns can be developed. To demonstrate tunability of the smart substrate, a frequency reconfigurable patch antenna was fabricated on Liquid Crystal Polymer substrate and bonded to the proposed smart substrate. The patch antenna was tested, which revealed that the center frequency of operation could be tuned from 2.38 GHz to 2.43 GHz by changing the DC current from 0 mA to 500 mA. Similarly, a transmission line based phase shifter was also fabricated on another smart substrate, which showed that the phase shifter could provide continuous 90° phase shift from 2.35 GHz to 2.15 GHz under different DC current bias conditions.

Microstrip balanced quad-channel diplexer using dual-open/short-stub loaded resonator

A microstrip balanced quad-channel diplexer is reported for the first time, using dual-open/short-stub loaded resonator (DOSLR/DSSLR) which consists of a uniform impedance end-shorted resonator loaded with two open/short stubs. The resonant frequencies of dual-open-stub loaded resonator (DOSLR) and dual-short-stub loaded resonator (DSSLR) under differential-mode (DM) and common-mode (CM) excitation are fully analyzed. Based on their respective characteristics, two individual balanced dual-band filters are initially designed with a frequency ratio of larger and smaller than 2 respectively. The designed filters are then combined to construct the first balanced quad-channel diplexer adopting distributed coupling technique. In order to demonstrate the efficacy of the proposed design methodology, a compact quad-channel balanced diplexer prototype (2.4/5.2 GHz and 3.2/4.75 GHz) is implemented and measured. Good agreement between the theoretical analyses and the measured data has been achieved.

Dual-mode dual-band balanced filter with high differential-mode frequency selectivity and enhanced common-mode suppression

A novel balanced dual-band microstrip filter based on dual-open-stub-loaded resonators (DOSLRs) is reported for the first time. The resonant frequencies of the DOSLR under differential-mode (DM) and common-mode (CM) excitation are analyzed. The presented dual-band balanced filter has inherent good CM suppression level within each DM passband because passbands of CM are misaligned with those of DM. In order to obtain a good CM suppression level in a relatively broad range and keep the desired DM response unaltered simultaneously, a stepped-impedance stub is added to the center of one DOSLR. From that purpose, the CM second harmonic of two DOSLRs are shifted away from each other. Furthermore, finite transmission zeros generated by the source-load coupling could be utilized to achieve high frequency selectivity in DM response. In addition, the positions of transmission zeros in CM response are also controllable to realize enhanced suppression within each DM passband. For validation, one balanced dual-band second-order filter working at 2.4 and 5.2 GHz is designed and fabricated, with its measured data matching well with the simulated counterparts.

Arbitrary frequency tunable radio frequency bandpass filter based on nano-patterned Permalloy coplanar waveguide (invited)

A well designed coplanar waveguide (CPW) based center frequency tunable bandpass filter (BPF) at 4 GHz enabled with patterned Permalloy (Py) thin film has been implemented. The operating frequency of BPF is tunable with only DC current without the use of any external magnetic field. Electromagnetic bandgap resonators structure is adopted in the BPF and thus external DC current can be applied between the input and output of the filter for tuning of Py permeability. Special configurations of resonators with multiple narrow parallel sections have been considered for larger inductance tenability; the tunability of CPW transmission lines of different widths with patterned Py thin film on the top of the signal lines is compared and measured. Py thin film patterned as bars is deposited on the top of the multiple narrow parallel sections of the designed filter. No extra area is required for the designed filter configuration. Filter is measured and results show that its center frequency could be tuned from 4 GHz to 4.02 GHz when the DC current is applied from 0 mA to 400 mA.

Electrically Tunable Bandpass Filter With Patterned Permalloy Thin-Film-Enabled Engineered Substrate

An electrically tunable bandpass filter based on an engineered substrate embedded with patterned permalloy (Py) thin film has been designed, implemented, and characterized. The bandpass filter is designed with metamaterial resonators to achieve a compact size; the designed filter is fabricated on a multilayered engineered substrate, which is composed of a layer of liquid crystal polymer, a layer of patterned Py thin film, and silicon substrate. The tunability of center frequency for the designed bandpass filter is dependent on the radio frequency (RF) characteristics of the implemented engineered substrate. The equivalent permeability of the Py thin film embedded in the engineering substrate is electrically tunable with the dc current, which thus provides high and tunable inductance densities for the split-ring resonators in the designed filter; the center frequency of the implemented bandpass filter is thus electrically tunable. The measured results show that the center frequency of the designed bandpass filter shifts from 2.37 to 2.45 GHz continuously when the applied tuning dc current is changed from 0 to 500 mA. The introduced unique concept of the engineered substrate provides design feasibility of filters with continuous frequency tunability, and the implementation of the engineered substrate enabled with the patterned Py thin film is suitable for the cost-effective fabrication of the arbitrary tunable RF devices.

High-Performance Electrically Tunable RF Phase Shifter With the Application of PZT and Permalloy Thin-Film Patterns

A fully electrically tunable RF phase shifter enabled with lead zirconate titanate (PZT) and Permalloy (Py) thin-film patterns based on the step impedance slow wave structure is well designed and fabricated. Tunable metal-insulator-metal structure capacitor enabled with the PZT thin film is integrated into the phase shifter so that the working frequency can be tuned by dc voltage, and the tuning voltage is significantly decreased compared with the previous research. The Py thin film is patterned and is deposited on the signal line of the proposed phase shifter that enables a tunable working frequency by dc current. Both inductive and capacitive tunability of phase shifter are achieved simultaneously. When 200 mA dc current is provided between two ports of phase shifter, the working frequency tuning range is 2% from 1.98 to 2.04 GHz. The tuning range is 5% from 1.98 to 2.08 GHz when 8 V dc voltage is added between the signal line and the ground. When both 8 V dc voltage and 200 mA dc current are applied, the working frequency of the proposed phase shifter is tunable from 1.98 to 2.12 GHz with a tunability of 7.1%.