A 2–40 GHz Probe Station Based Setup for On-Wafer Antenna Measurements

A probe station based setup for on-wafer antenna measurements is presented. The setup allows for measurement of return loss and radiation patterns of an on-wafer antenna-hence-forth referred to as the antenna under test (AUT), radiating at broadside and fed through a coplanar waveguide (CPW). It eliminates the need for wafer dicing and custom-built test fixtures with coaxial connectors or waveguide flanges by contacting the AUT with a coplanar microwave probe. In addition, the AUT is probed exactly where it will be connected to a transceiver IC later on, obviating de-embedding of the measured data. Sources of measurement errors are related to calibration, insufficient dynamic range, misalignment, forward scattering from nearby objects, and vibrations. The performance of the setup is demonstrated from 2 to 40 GHz through measurement of an on-wafer electrically small slot antenna (lambda₀/35 times lambda₀/35,3.5 times 3.5 mm²) radiating at 2.45 GHz and an aperture coupled microstrip antenna (2.4 times 1.7 mm²) radiating at 38 GHz.     

De-embedding method for on-wafer RF CMOS inductor measurements

In this work, an accurate de-embedding method for on-wafer RF measurements of CMOS large area devices like the inductors is presented. The method uses distributed and lumped-element models to represent the parasitic elements. The interconnect parasitics are calculated using the transmission line theory. The proposed method is compared to existing de-embedding methods. The validity of the method is checked with the DC resistance value of the interconnects as calculated from the layout and as extracted from measurements, as well as with inductance results of the fabricated inductor, extracted from measurements and from electromagnetic simulations. On-wafer S-parameter measurements have been taken from a test chip up to 20 GHz.     

The microwave properties of Li doped 0.7(Ba,Sr)TiO3-0.3MgO thick film interdigital capacitors on the alumina substrates

The crystalline and electrical properties of Li doped 0.7(Ba,Sr)TiO₃-0.3MgO thick film interdigital capacitors have been investigated. Screen printing method was employed to fabricate Li doped 0.7(Ba,Sr)TiO₃-0.3MgO thick films on the alumina substrates. (Ba,Sr)TiO₃ materials have high dielectric permittivity (>500 @ 1 MHz) and low loss tangent (0.01 @ 1 MHz) in the epitaxial thin film form. To improve dielectric properties and reduce sintering temperature, MgO and Li were added, respectively. 10 μm thick films were screen printed on the alumina substrates and then interdigital capacitors with seven fingers of 200 μm finger gap were patterned with Ag electrode. Current-voltage characteristics were analyzed with elevated temperature range. Up to 50 °C, the thick films showed positive temperature coefficient of resistivity (dρ/dT) of 6.11 × 10⁸ Ω cm/°C, then film showed negative temperature coefficient of resistivity (dρ/dT) of −1.74 × 10⁸ Ω cm/°C. From the microwave measurement, the relative dielectric permittivity of Li doped 0.7(Ba,Sr)TiO₃-0.3MgO thick films interdigital capacitors were between 313 at 1 GHz and 265 at 7 GHz.     

Microwave absorption and permittivity of polyaniline thin films using overlay technique

This paper reports the use of nonresonating microstripline for investigation of polyaniline thin film using overlay technique. Microwave absorption, DC conductivity, microwave conductivity, shielding effectiveness and microwave permittivity and dielectric loss of the conducting PANI films are reported. DC conductivity was between 0.15×10⁻³ and 3.13×10⁻³ S/cm. Microwave conductivity was between 0.1 and 10 S/cm. The PANI films coated on alumina gave shielding effectiveness values of −1 to −8 db. The ε′ was between 40 and 350. Measurements have been carried out over the frequency range 8.2-18 GHz. The effect of thickness of the overlay is also reported.     

Power performance and scalability study of AlGaAs/GaAs double-recessed pseudomorphic high electron mobility transistors on unthinned substrate for coplanar waveguide circuit applications

We have investigated the power performance and scalability of AlGaAs/GaAs Double-Recessed Pseudomorphic High Electron Mobility Transistors (DR-PHEMTs) at 10 GHz on an unthinned GaAs substrate for CoPlanar Waveguide (CPW) circuit applications. It was found that the output power varied linearly with the logarithm of the device’s gate width ranging from 200 to 1000 μm. It increased at a rate of 0.01 dB/μm. That worked out to a doubling of output power (or 3 dB) for every 300 μm increase in the gate width. Gain decreased at a rate of about 0.005 dB/μm while PAE generally improved when the gate width was increased. As for DC measurement, the maximum transconductance of the device was about 375 mS/mm at V_G = −0.5 V and V_DS = 3 V. The gate-drain breakdown voltage (BV_GD) measured was −20 V, defined at I_G = −1 mA/mm. The microwave performance of the devices was measured on-wafer using a load-pull system at a bias of V_G = −0.5 V and V_DS = 8 V. For a device with a gate width of 1 mm, its saturated CW output power, gain and PAE value at 10 GHz was 27.5 dBm (0.55 W), 8 dB and 48%, respectively. At this same set of bias conditions, the value of f_t and f_max was 40 and 80 GHz, respectively.     

隔离器用M型钡铁氧体陶瓷电磁性能的研究

以BaCO3和Fe2O3为原料,采用传统陶瓷工艺制备了六角磁铅石M型钡铁氧体陶瓷。采用XRD和SEM表征了样品的晶体结构和形貌特征。采用同轴法测试了样品的复介电常数(ε)和磁导率(μ),利用带状线法测试了其微波吸收性能。结果表明:经不同的烧结制度均制备出了物相单一、结晶良好的钡铁氧体样品;1 200℃保温8h制备的样品ε最大;1 250℃保温4 h制备的样品具有最高的μ,且在10.2 GHz的频率下,吸收损耗可达5.0 dB/mm。     

Process development in metal/BCB multilayer interconnections of MMCM with embedded chip in Si substrate

A vertical interlayer connection via (VILCV) fabrication process is presented. This process is used for the interconnection of multilayer benzocyclobutene (BCB) based microwave multichip modules (MMCM). The excellent planarity of BCB allows VILCV to be formed using gold electroplating or stud bumps prior to BCB application. And mechanical polishing (MP) planarization is adopted to expose the VILCV, enabling interconnection between different layers. Subsequently upper interconnection is patterned. Metal/BCB multilayer structure can be made by repeating above steps. This approach eliminates the need for laser drilling and plasma etching. Both four terminal Kelvin structures and via chains are fabricated as test vehicles. Finally, a transition of transmission lines in different layers and a packaged MMIC embedded in Si substrate are presented and measured in high frequency range up to 20 GHz. The results show there is only minimal performance degradation.     

Multiband BPF with wide upper stop band using asymmetrically positioned stub loaded open loop resonators

In this paper, asymmetrically positioned stub loaded open loop resonators with pseudo interdigital coupling are used to design compact multiband planar bandpass filters. The first design pertains to a dualband BPF that operates at 3.5 GHz and 5.7 GHz. The parameters like position of stub, which quantifies the asymmetry, and length of stub are further optimised using real coded genetic algorithm to evolve a triband BPF. The evolutionary design procedure is supported with an example of triband BPF having passband at 3.5 GHz, 5.5 GHz and 6.8 GHz, respectively. The transmission line models for both filters are developed as well as fabricated prototypes are realised and tested. There is a good agreement between the measured and simulated results. The measured insertion loss at first and second band centred around 3.5 GHz and 5.7 GHz of the dual band BPF are 1.5 dB and 1.25 dB, respectively. For the triband BPF the values are 1.24 dB, 1.6 dB and 1.8 dB at 3.5, 5.5 and 6.8 GHz, respectively. The dualband design covers the WiMAX and IEEE 802.11a bands where as the triband design also covers the 6.8 GHz RFID frequency.     

An analysis for AlGaN/GaN modulation doped field effect transistor using accurate velocity-field dependence for high power microwave frequency applications

An analytical model of Al_0.15Ga_0.85N/GaN modulation doped field effect transistor (MODFET), which uses an accurate velocity field relationship and incorporates the dominant effect of piezoelectric polarization induced charge at the AlGaN/GaN interface is presented. The effect of traps has also been taken into account. The calculated DC characteristics are in excellent agreement with the measured data. The model is extended to predict the microwave performance of the device. High current levels (>500 mA/mm), large transconductance (160.83 mS/mm) and a high cutoff frequency (9.6 GHz) have been achieved analytically and are in close agreement with the experimental data.     

GaAs功率单片脉冲在片测试技术研究

讨论了功率单片在片脉冲测试中在片校准技术、脉冲功率测试技术等难题,并在讨论以上问题的基础上,实现工程化应用,该测试技术能够有效覆盖至40GHz。在建立的脉冲大功率在片测试系统上对输出功率典型值5W的GaAs功率单片放大器进行测试验证,测试结果和装架测试结果相比较,输出功率误差<0.2dB。