Hsien-Shun Wu

Surface-wave leakage from substrate integrated waveguide on grounded dielectric substrate

This paper presents the surface-wave leakage from a substrate integrated waveguide (SIW) on a grounded dielectric substrate, which propagates the TM0 mode at the lowest order. The hybrid generalized scattering matrix (GSM) formulation, describing the electromagnetric field inside the rectangular waveguide walls, combined with the finite-element method(FEM), accurately depicting the fields surrounding the microstrip and distributing alongside the infinitely extended grounded substrate, establishes a rigorous formulation to tackle the periodic structure. The resulting lowest order dispersion characteristics show very good agreement with those of the TE10 mode of an ideal rectangular waveguide, when the gap between the posted walls is approaching one thousandth posted walls diameter. Careful investigation of the electromagnetic field in the plane parallel to the ground plane shows that the leakage is 1) a TM0 surface mode, and 2) significant near and below the cutoff frequency of the rectangular waveguide section of the SIW.

Anomalous Dispersion Characteristics of Periodic Substrate Integrated Waveguides From Microwave to Terahertz

This paper presents the anomalous dispersion characteristic of a periodic substrate integrated waveguide (SIW) with results obtained by a rigorous formulation using the hybrid generalized scattering matrix (GSM) and finite-element method (FEM), showing two types of anomalous modal behaviors, namely: 1) TM0 surface wave leakage in connection to the near cutoff transverse resonance of a rectangular waveguide section alternating with either microstrip or parallel sections and 2) complex modes inside the lowest TE01-like propagating zone. A rigorous limiting case study of the SIW via spacing approaching less than 10% of via diameter validated the proposed hybrid GSM/FEM formulation and enabled the detailed description of various types of modes, namely, propagating TE01-like, a pair of complex modes, and above the stopband regimes, respectively. Convergence analysis and comparisons to the existing literature were carried out to validate the proposed method in addition to the limiting case study. Measured results of the CMOS prototypes validate the theoretical prediction from 325 to 450 GHz and confirm the accuracy of the proposed method.

Leakage of CMOS slow-wave left-handed transmission line on the perforated ground plane

This paper presents the leakage phenomenon of the left-handed transmission line (LH-TL) in the slow-wave region. The 15 μm unit-cell of the LH-TL is implemented based on the 0.13 μm 1P8M CMOS technology. The dispersion curves extracted by the measured scattering parameters show that the increasing of the normalized attenuation constant (α/β0) above 320 GHz indicates the transverse electric (TE)-like leakage phenomenon of the proposed LH-TL in the slow-wave region. The theoretical observations based on the three-dimensional electromagnetic field analyses confirmed the leakage phenomenon.

Dispersion characteristic a periodic substrate integrated waveguide of parallel metallic plates

This paper presents the dispersion characteristic of a substrate integrated waveguide (SIW) of parallel metallic plates. The hybrid generalized scattering matrix and finite-element method (GSM/FEM) method accurately depicting the fields inside the rectangular waveguide section, transitions, and external parallel-plate region. The presented method establishes a rigorous approach to tackle the periodic structure. The dispersion propagation characteristics extracted by the hybrid GSM/FEM method show a region of complex modes between 49 GHz and 52.5GHz. Preliminary study of this complex modes region indicates the mode-coupling of the space harmonics leads to the interesting phenomenon, displaying a null transmission of the SIW TE10 mode. The theoretical three-dimensional electromagnetic field analyses confirmed the null transmission.

CMOS 170 GHz combline bandpass filter

A second-order combline bandpass filter (BPF) in the standard 0.13 μm 1P8M CMOS technology is presented. The miniaturized resonator consists of the on-chip thin-film microstrip transmission line and an interdigital capacitor. The characteristics of the transmission line and the capacitor are theoretically extracted for the filter syntheses. Based on the reported design procedures, a CMOS prototype are implemented and experimentally characterized, showing an insertion-loss of 2.7 dB at 170 GHz with a fractional bandwidth of 10 %. The chip size is 86.5 μm by 45 μm.

K-band 100.8 mW beamforming SOC with 249.8 ± 22.8 pico-second group-delay in 0.13 µm CMOS

A K-band four-element beamforming system-on-chip (SOC) is presented. In the SOC, the attenuators and the phase shifters, designed in the reflection topology, are realized by two types of the on-chip synthetic transmission lines. The cascode amplifier, as the first stage in the receiving path, provides a gain of 20 dB to compensate all the losses of the passive components, and use dual feedback loops to minimize the group delay variation. The SOC prototype is fabricated by using 0.13 μm CMOS technology, and characterized through the on-wafer measurements. The measured input and output return loss are less than −9.8 and −14.8 dB in the 50Ω system. The total receiving gain and the noise figure are 5.9 dB and 7.5 dB, respectively. The prototype can continuously make 360° phase shifting with root-mean-square (RMS) errors less than 1.5° and 0.6 dB. The measured group-delay is 249.8 pico-second (ps) with a variation of 222.8 ps from 22 to 26GHz. The input P1dB and IIP3 are −19.8 dBm and −8.3 dBm at 24GHz. The channel-to-channel isolation is higher than 31.6 dB in a chip area of 0.00632 λ0 at 24GHz.

V-band 130 nm CMOS multistage amplifier incorporating gain-boosting technique

To design a high gain amplifier at V-band using 130 nm CMOS process, the gain-boosted technique is adopted to increase the maximum achievable gain (Gmax). Impedance matching synthesis is investigated for input and output matching circuits based on transmission lines. By adopting appropriate transistor size, a single stage amplifier can achieve the maximum gain of 10 dB at 53 GHz.

Terahertz square ring resonators incorporating CMOS left-handed transmission line

This paper presents the designs of the monolithic square ring resonators based on the composite right/left-handed (CRLH) transmission line (TL) operated in left-handed slow-wave region. The proposed resonator is fully realized by only using CRLH cells, and its design equation is derived based on the left-handed guiding properties, indicating how the frequency-dependent slow-wave factor affecting the resonant modes inside the ring resonator. The quality-factor (Q-factor), which is theoretically extracted from the complex propagation constant of the proposed CMOS LH-TL, exceeds 25 from 386 GHz to 486 GHz. Two left-handed (LH) ring resonators, which consist of eight and sixteen unit cells, are fabricated in the standard 0.13 μm 1P8M CMOS foundry. From 325 GHz to 500 GHz, the on-wafer measured results closely agree with the theoretical predictions, showing that the 8-cell LH resonator has two resonating frequencies at 362 GHz and 468 GHz with the unload Q-factors of 14.2 and 21.2, respectively. The 16-cell LH resonator has Q-factors of 17.6 and 22.3 at the resonating frequencies at 389 GHz and 482 GHz.

THz monolithic antenna incorporating symmetrical left-handed coupled-line

This paper presents a THz monolithic antenna implementation based on the left-handed coupled-line (LH CL). The theoretical dispersion curves extracted by the scattering parameters show that the odd-mode normalized attenuation constant (α_odd/β₀) of the left-handed coupled-line in the leakage region (β_odd/β₀<;1) is higher than that of the single left-handed transmission line in the leakage region (β/β₀<;1), indicating the high potential on miniaturized antenna design. An antenna prototype, including the on-chip matching network, is designed based on the dispersion curve, and fabricated by the standard 0.13 μm 1P8M CMOS technology. The measured return-loss of the prototype is less than -13 dB at 422 GHz, The simulated antenna gain is about 2.6 dBi at 420 GHz.

A novel compact leaky wave antenna incorporating the dual-periodical loading

This paper presents a novel leaky wave antenna (LWA) loaded by periodical open stubs and holes. The complex propagation constants of the first higher order mode of the periodically loaded microstrip, so-called the EH1 mode, are extracted by the field eigenvalue approach, leading to control the radiation characteristics by changing the loading conditions. By doubling the length of open stub, the operating frequency of the LWA can be shifted 8.9% toward to the lower frequency. The comparison of the dispersion curves between the loaded and conventional microstrips shows 20% width reduction on synthesizing the EH1 mode. Two 9GHz and 10GHz practical prototypes are designed based on the proposed methodology and fabricated by using the multilayer printed circuit board (PCB) technology. The measured return-losses of two LWA prototypes are lower than 10 dB. The measured antenna gains of two LWA are 5.37 dBi and 6.89 dBi. The maximum gains are 6.05 dBi and 7.43 dBi at 9.2 and 10.1GHz. The beam scanning angles are 7 degrees and 4 degrees when the frequency is increased 0.2GHz.