Cheng-Lin Cho

Inkjet-Printed Interdigital Coupled Line Filter on Liquid Crystal Polymer Substrate

This letter investigates inkjet-printed interdigital coupled line bandpass filters on liquid crystal polymer substrates. Silver nanoparticle colloidal solution was used as the printing ink. Various numbers of passes were used to print the samples to study the changes in conductivity and uniformity. Samples were then sintered in an oven to remove excess solvent and material impurities. The silver-film conductivity of the conductive ink was ~1×107 S/m. The interdigital coupled line bandpass filter was printed with an inkjet printing system. The study achieved a minimal insertion loss and maximal return loss of -3.6 and -24 dB at 25.7 GHz, respectively.

Inkjet Printed Series-Fed Two-Dipole Antenna Comprising a Balun Filter on Liquid Crystal Polymer Substrate

This paper presents a series-fed two-dipole antenna, fabricated on a liquid crystal polymer (LCP) substrate using inkjet-printing technology. The radio frequency characteristics of inkjet-printing silver film onto an LCP substrate are studied using the microstrip line. The proposed antenna consists of two modified dipole elements of distinct lengths: a modified ground plane and a balun filter yielding a wide bandwidth with bandpass responses. The proposed antenna can be used at frequency band of 26-33 GHz. The bending behaviors of the microstrip line and antenna are also measured. Inkjet printing on LCP substrates provides a low-cost, compact, and flexible packaging solution that can be used in future communication technology.

Hairpin bandpass filter on Liquid Crystal Polymer substrate using inkjet printing technology

Inkjet-printing technology is utilized to fabricate a bandpass filter on a Liquid Crystal Polymer (LCP) substrates. Silver nanoparticle colloidal solution is used as the printing ink. The conductivity and thickness of silver film are 1~2×107 Siemens/m and 3.6 μm, respectively. The hairpin bandpass filter has been developed using inkjet printing technology. Bending effect causes frequency shift and insertion loss reduction due to material deformation while bending the LCP substrate.

Inkjet-Printed Multilayer Bandpass Filter Using Liquid Crystal Polymer System-on-Package Technology

This paper presents the fabrication of an inkjet-printed multilayer bandpass filter using the liquid crystal polymer (LCP) system-on-package (SOP) technology. The LCP-SOP technology adopted by lamination bonding process reduces the occupied area of a device and is suitable for radio frequency (RF) package applications. The surface morphologies and RF performance of the inkjet-printed silver film on an LCP substrate after the lamination bonding process, which entails applying high temperatures and pressures, were observed and analyzed. Acceptable performance of the inkjet-printed silver film of an optimal lamination bonding condition was 0.69 MPa at 270 °C. Using the inkjet-printing and LCP-SOP technologies, a miniature bandpass filter was created with a minimal S21 value and a maximal S11 value of -1.5 and -17.4 dB at 10.6-14.5-GHz passband, respectively. A strain effect of silver line and bandpass filter was also analyzed. The results demonstrated the effectiveness of the proposed design methodology and the fabrication technique.

Enhanced sub 20-nm FinFET performance by stacked gate dielectric with less oxygen vacancies featuring higher current drive capability and superior reliability

HK-2/HK-1 stacked dielectric was proposed as the gate dielectric for sub-20 nm FinFET technology. Compared to single HK-1 dielectric, the stacked gate dielectric exhibits superior performance in terms of improved drive current by 20~22% and increased transconductance by ~22%. The main reason accounting for the better performance, besides the higher gate capacitance by 4%, is the enhanced carrier mobility by ~33% resulting from less remote scattering due to smaller amount of charged oxygen vacancies which was physically confirmed by EELS and XPS. Owing to the reduced oxygen vacancies, from bias temperature instability and lifetime test, the stacked gate dielectric demonstrates augmented reliability as well. Most importantly, HK-1 and HK-2 are common dielectrics completely compatible with typical processes, rendering the stacked dielectric a promising one for next-generation FinFETs technology.

Bending Effect of an Inkjet-Printed Series-Fed Two-Dipole Antenna on a Liquid Crystal Polymer Substrate

This letter presents a series-fed two-dipole antenna fabricated on a flexible liquid crystal polymer (LCP) substrate by using inkjet printing technology. The proposed antenna consists of two modified dipole elements of distinct lengths, a director element, a modified ground plane, and a balun filter, yielding a wide bandwidth with bandpass responses. The proposed antenna can be used at a frequency band of 26-32 GHz. The bending behaviors of the antennas with and without director elements were analyzed. The bending effect of the antenna should be considered when calculating the gain loss and bandwidth reduction. Inkjet printing on LCP substrates provides a low-cost, compact, and flexible packaging application that can be used in probable and flexible communication technology.

Design of an S-band 0.35 µm AlGaN/GaN LNA using cascode topology

This paper presents an S-band low noise amplifier that uses a two-stage configuration. The first stage has a cascode topology and the second stage has a RC feedback topology. The S-band LNA uses a 0.35 μm AlGaN/GaN HEMT on a Si-substrate. The results show a maximum gain of 17.2 dB, a minimum noise figure of 2.9 dB and an input/output return loss greater than 9.2/10 dB. The input IIP3 at 2.8 GHz is 2.5 dBm and the unit consumes 230 mW of power.

A 3.5 GHz antiparallel diode pair mixer in GaN-on-Si HEMT technology

This paper presents a 3.5 GHz antiparallel diode pair mixer using a 0.35 μm GaN-on-Si HEMT technology. The antiparallel diode pair mixer has a conversion gain of -17.2 dB at 3.5 GHz. The LO-to-RF, LO-to-IF, and RF-to-IF isolation are -47.9, -34.8 and -27.5 dB at 3.5 GHz, respectively. The measured P1dB and third-order intercept point (IIP3) are +7 dBm and +17 dBm, respectively. The mixer occupies a chip area, including probing pads, of 0.9 mm2.

Direct Fabrication of Inkjet-Printed Dielectric Film for Metal–Insulator–Metal Capacitors

In this study, an inkjet-printed dielectric film that used a polymer-based SU-8 ink was fabricated for use in a metal–insulator–metal (MIM) capacitor. Thermal treatment of the inkjet-printed SU-8 polymer film affected its surface morphology, chemical structure, and surface wettability. A 20-min soft-bake at 60°C was applied to eliminate inkjet-printed bubbles and ripples. The ultraviolet-exposed SU-8 polymer film was crosslinked at temperatures between 120°C and 220°C and became disordered at 270°C, demonstrated using Fourier-transform infrared spectroscopy. A maximum SU-8 polymer film hard-bake temperature of 120°C was identified, and a printing process was subsequently employed because the appropriate water contact angle of the printed film was 79°. Under the appropriate inkjet printing conditions, the two-transmission-line method was used to extract the dielectric and electrical properties of the SU-8 polymer film, and the electrical behavior of the fabricated MIM capacitor was also characterized.

Inkjet-Printed Interdigital Bandpass Filter with Wide Stopband Using Multilayer Liquid Crystal Polymer Technique

This article presents a two-layer inkjet-printed interdigital bandpass filter using lamination bonding process on liquid crystal polymer (LCP) substrates for radio frequency electronic applications. Various percentages of torque force were applied over a 4 × 4 cm2 area with a 942 kg fixed force in the lamination bonding process. The insertion loss and surface morphology of the inkjet-printed silver film were examined on various torque forces to develop the lamination bonding process. The lamination bonding was performed at 12% torque and 270°C. A three-dimensional bandpass filter was realized with a of −2.2 dB at 11.5 GHz with a 17% fractional bandwidth. A multilayer inkjet-printed bandpass filter was successfully developed to verify the design methodology and fabrication of inkjet-printing technology and lamination bonding technique for a three-dimensional integrated circuit package.