Kamel Haddadi

Measurement Techniques for RF Nanoelectronic Devices: New Equipment to Overcome the Problems of Impedance and Scale Mismatch

The emergence of new materials (nanowires, nanotubes, graphene tapes, and thin films) and devices with nanoscale dimensions give rise to the necessity for developing dedicated techniques that will allow their electrical characterization at high-frequency range. In this article, two possible views have been highlighted to tackle the issue of the measurement of high-impedance nanoscale devices. The first solution is based on the integration of a high-impedance reflectometer and a nanoscale device on the same chip. The microwave impedance of a single CNT has been successfully measured up to 6 GHz using this technique. The second solution consists of inserting an adjustable microwave interferometer between a traditional VNA and the high-impedance device. The interferometer allows adjustment of the impedance to be measured to the highest measurement sensitivity of the measurement system. In particular, capacitances down to 0.35 fF have been measured with an error estimated to be less than 10% using the interferometric technique combined with a scanning microwave microscope. These proofs of concept on one-port nanodevices open the route towards the case of two-port active devices with high impedance. Advances in the manufacturing of next-generation nanodevices will depend on our ability to measure electrical properties and performance characteristics accurately and reproducibly at the nanoscale regime over a broad frequency range.

Formulation for Complete and Accurate Calibration of Six-Port Reflectometer

An accurate technique for six-port reflectometers calibration is presented in this paper. The method based on a spatial Fourier analysis incorporates nonlinearity and mismatching effects as a part of the calibration procedure. The technique makes use of impedance data distributed on the whole Smith chart to increase the measurement accuracy. A straightforward least square algorithm is used to fully calibrate the six-port reflectometer. Experimental data in the millimeter-wave frequency range is provided to validate the technique.

Interferometric technique for microwave measurement of high impedances

An interferometric technique for accurate and broadband measurement of microwave impedances is proposed. The method is based on the association of a vector network analyzer and a precise interferometer built up with a power divider, a phase-shifter and an attenuator. Advantages such as simplicity of operation, broadband operation and high accuracy are achieved. The technique can be applied in a wide range of applications. In particular, an experimental demonstration of a near-field microwave microscope operating in liquid media is proposed.

Performance of a Compact Dual Six-Port Millimeter-Wave Network Analyzer

This paper presents a millimeter-wave network analyzer incorporating two six-port correlators for the measurement of the reflection and transmission coefficients of a device under test in the frequency band 59-61 GHz. An instrumentation integrating the hardware and software resources, including advantages such as robustness, compactness, relatively low cost, small size, and real-time operation, is developed. The millimeter-wave part of the system is implemented on a thin alumina ceramic substrate. The proposed solution eliminates the need for complex heterodyne schemes and for bulky tuning mechanisms generally found in dual six-port network analyzers. Associated to this system, an explicit calibration procedure is proposed. The performance, in terms of measurement accuracy, is evaluated by comparing the results obtained from the system proposed with those given by a conventional network analyzer.

Homodyne dual six-port network analyzer and associated calibration technique for millimeter wave measurements

This paper presents a homodyne six-port network analyzer operating around 60 GHz. The power detection is realized by using Schottky zero-bias diodes. The conception of the system is driven by means of low-cost and simplicity of realization considerations. A circulator-less topology implemented on an alumina microstrip technology and a detector linearization method are proposed to measure simultaneously the reflection and transmission coefficients of a device under test (D.U.T.). The system, initially conceived and optimized at 60 GHz, takes advantage of the development of a calibration model to support measurements in the 59-62 GHz band

Interferometric Technique for Scanning Near-Field Microwave Microscopy Applications

An interferometric technique for scanning nearfield microscopy applications is proposed. The method is based on the association of a vector network analyzer, an evanescent microwave coaxial probe and a precise interferometer built up with a power divider, a phase-shifter and an attenuator. Advantages such as simplicity of operation, broad frequency band capabilities and high measurement sensitivity are achieved. In particular, a scanning near-field microwave microscope is built and experiments related to the measurement sensitivity in the frequency range 2-6 GHz are demonstrated.

Geometrical Optics-Based Model for Dielectric Constant and Loss Tangent Free-Space Measurement

A microwave free-space reflection method for determining the complex permittivity of planar dielectric materials is demonstrated. The method makes use of the measurement of the near-field microwave reflection coefficient of a metal-backed sample. The modeling of the structure and its calibration are based on geometrical optics considering spherical electromagnetic waves propagating through the material. The technique that presents a number of features such as low-cost, compactness, robustness, and reliability is a good candidate for industrial applications. As a demonstration, dielectric parameters extraction of building materials is experimentally demonstrated for wireless local area network operations in the 2.45- and 5-GHz bands.

60-GHz Near-Field Six-Port Microscope Using a Scanning Slit Probe for Subsurface Sensing

A new six-port based near-field millimeter-wave microscope using a scanning slit probe is proposed for subsurface sensing applications. The combination of a six-port reflectometer and a slit probe presents a viable and promising alternative to the costly heterodyne principle. The system presents advantages such as compactness, robustness, and low cost. To evaluate its performance, the spatial resolution is experimentally verified.

Scanning Microwave Near-Field Microscope Based on the Multiport Technology

A multiport based near field high frequency microscope is proposed for local nondestructive evaluation and testing applications. The combination of the multiport technology and near-field microscopy methods present advantages such as low cost, compactness, real-time operation, high spatial resolution and versatility. In particular, experimental demonstrations of a multiport near-field microscope is described in microwave frequency range. The spatial resolution of the instrument is experimentally verified to evaluate the performance of the technique proposed.

Measurement accuracy and repeatability in near-field scanning microwave microscopy

We report on the accuracy and repeatability tests for near-field scanning microwave microscopy applications by associating a network analyzer and an evanescent microwave probe (EMP). A broadband matching network based on an interferometric technique is used to achieve a strong electromagnetic coupling between the probe tip and the material in the frequency range 1-20 GHz. The electromagnetic coupling between the probe and a planar metallic sample is investigated using numerical simulations based on finite element method (FEM). Experimental validations show that the measurement sensitivity is enhanced in the vicinity of the probe tip. Measurement accuracy and repeatability of the system are provided that are instructive and beneficial to further experiments.