Kaixue Ma

A compact size coupling controllable filter with separate electric and magnetic coupling paths

This paper presents the characteristics of a miniaturized microstrip filter, which has two separate coupling paths: electric coupling path and magnetic coupling path between two resonators. Either magnetic coupling or electric coupling in two paths can be dominant in the total coupling coefficient of the inter-stage resonators with the similar configuration, but different positions of transmission zero points (ZPs). Based on the proposed filter topology, second- and fourth-order filters have been designed and fabricated for the first time. Advantages of using this type of filter are not only its low insertion loss and much more compact size, but also its controllable transmission ZPs.

New Ultra-Wide Stopband Low-Pass Filter Using Transformed Radial Stubs

A new type of low-pass filter (LPF) with ultra-wide band rejection and compact size by using a proposed transformed radial stubs (TRSs) is introduced and investigated. The operating mechanism of the filter is investigated based on proposed equivalent-circuit model. The implemented LPF with 1-dB cutoff frequency fc of 3 GHz demonstrates stopband rejection up to 8 fc i.e., 24 GHz. The skirt selectivity is achieved up to -144 dB per octave through multiple-zero generation using TRSs. The measured passband insertion loss is less than 1.5 dB. I/O loading cells are used to further extend the deep stopband to more than 13 fc i.e., above 40 GHz. The size of the four-cell LPF is only 0.31 λg × 0.24 λg, (λg is the guide wavelength at center cutoff frequency) without using any lumped elements.

A Wideband and High Rejection Multimode Bandpass Filter Using Stub Perturbation

A novel multimode bandpass filter with high and wide rejection band is proposed by using an open stub. The open-stub has two functions in the filter: (1) perturbation for the multimode operation and (2) zero point generation at the stopband for the stopband control. With proper input/output coupling, additional two poles, i.e., four poles, can be generated for the proposed filter structure. The design is then verified by experiment. The single structure four-mode filter has low insertion loss, good stopband performance, and compact size and linear phase.

Compact Dual-Band Bandpass Filters Using Novel Embedded Spiral Resonator (ESR)

Compact dual-band bandpass filters (BPFs) are proposed using the novel embedded spiral resonators (ESRs) in this letter. Each ESR consists of two sets of spiral-lines embedded in a microstrip rectangular open-loop (MROP). The resonator has two functions in the filter: 1) dual-resonance operation mainly provided by the spiral-lines is employed to generate two passbands simultaneously. 2) MROP acting as the dual-feeding structure is introduced to achieve good input/output (I/O) coupling for both passbands. With proper tapping scheme, additional transmission zeros can be obtained to improve the passband selectivity. To verify the principle above, two dual-band BPFs are implemented. These filters with passbands operated at 2.4/5.2 GHz and 2.45/5.7 GHz can finely meet the wireless local area network (WLAN) bands requirements, respectively.

Novel Defected Ground Structure and Two-Side Loading Scheme for Miniaturized Dual-Band SIW Bandpass Filter Designs

This letter reports a novel back-to-back E-shaped defected ground structure (DGS) and two-side loading scheme for miniaturized dual-band substrate integrated waveguide (SIW) bandpass filter (BPF) designs. The SIW loaded by novel DGS supports evanescent-mode wave propagation below the cut-off frequency of SIW, while achieves two transmission poles at the passband and two controllable transmission zero points. Furthermore, the novel loading scheme by loading different-sized DGS resonators on two sides of SIW is proposed for dual-band BPF designs. To validate the design and analysis, a 2.4/5.2 GHz filter prototype was designed. In good agreement with theoretical results, the measured results of the dual-band filter achieve insertion losses of 3.6 and 3.1 dB, and fractional bandwidths of 5.8% and 6.45% at 2.4 and 5.2 GHz, respectively. The filter size is only 408 mil × 420 mil.

An Ultra-Compact Hairpin Band Pass Filter With Additional Zero Points

A novel quasi-hairpin filter is presented in this letter. The filter shows ultra-compact size, steep selectivity, and deep stopband rejection with additional transmission zero points. The fourth-order filter operating at 1.69GHz with a fractional bandwidth of 10% occupies the active area of 5.5mmtimes6.2mm (0.031lambda0times0.035lambda0)

Miniaturized 60-GHz On-Chip Multimode Quasi-Elliptical Bandpass Filter

A 60-GHz on-chip multimode bandpass filter (BPF) is implemented using a sandwich capacitor. The proposed loaded sandwich capacitor shows functions of multimode perturbation and stopband control in the BPF design. An additional magnetic coupling path from the source to the load is introduced to generate two extra zeros. Thus the quasi-elliptical filter response is achieved. The proposed filter implemented with a commercial SiGe BiCMOS process demonstrates a low insertion loss of 4 dB and compact size of only 0.16 mm2.

Experimentally investigating slow-wave transmission lines and filters based on conductor-backed CPW periodic cells

Several conductor-backed coplanar waveguide (CBCPW) transmission lines and filters with/without loading are investigated experimentally. Slow-wave periodic transmission lines of nine finite cells and periodic quarter-wavelength band pass filters (BPFs) are designed and fabricated based on the conductor-backed CPW using thin-film technology. The size of each line or filter is only 4.38mm /spl times/ 1.5mm. It is revealed that both coupling enhancement and size reduction can be realized by periodic loading on CBCPW.

Temperature-Compensated dB-linear Digitally Controlled Variable Gain Amplifier With DC Offset Cancellation

This paper presents a compact digitally controlled variable gain amplifier (DVGA) with capabilities of both temperature compensated linear-in-decibel (dB-linear) gain control and dc offset cancellation (DCOC) without making use of either the feedback or the feed-forward loop. The proposed DVGA design is a three-stage inductorless cascaded amplifier that is integrated with a temperature-compensated dB-linear gain control, a DCOC, an output common mode feedback, a 6-bit digital gain control (with a 64-step resolution), a power shutdown mode, and a linearizer for improving the 1-dB gain compression point. The design is fabricated using a commercial 0.18-μm SiGe BiCMOS technology. The DVGA has a measured gain range of 18.4 dB with an average step size of 0.3 dB, a 3-dB bandwidth from 2 MHz to 1.9 GHz with a ±0.75-dB gain flatness from 2.75 MHz to 1.2 GHz, an input 1-dB gain compression point better than -12.5 dBm, an input return loss better than 12 dB, an output return loss better than 16 dB, and a dc power consumption of 12.2 mW from a 1.8-V supply. The core DVGA, by excluding the I/O measurement pads, occupies a die area of 160 μm × 300 μm.

Miniaturized 3-bit Phase Shifter for 60 GHz Phased-Array in 65 nm CMOS Technology

The letter presents a compact 3-bit 90 ° phase shifter for phased-array applications at the 60 GHz ISM band (IEEE 802.11ad standard). The designed phase shifter is based on reflective-type topology using the proposed reflective loads with binary-weighted digitally-controlled varactor arrays and the transformer-type directional coupler. The measured eight output states of the implemented phase shifter in 65 nm CMOS technology, exhibit phase-resolution of 11.25 ° with an RMS phase error of 5.2 °. The insertion loss is 5.69 ± 1.22 dB at 60 GHz and the return loss is better than 12 dB over 54-66 GHz. The chip demonstrates a compact size of only 0.034 mm2.