TRL Calibration Research Articles

Investigation of Variation in On-Si On-Wafer TRL Calibration in Sub-THz

This work presents possible variations in TRL calibrated on-wafer S-parameters measurements with change in the on-wafer reflect design (pad open to pad short or vice-versa) in the TRL calibration method. The variations in each error-term values due to the change in the on-wafer reflect in the TRL calibration are examined which shows the source match and reflect tracking as possible error-terms bringing the observed variations in the on-wafer TRL calibrated S-parameter. In order to identify sources introducing these variations in the error-terms values and the S-parameters, TRL calibrated on-wafer S-parameters (S11 and S22) of symmetric structures (both reflects, i.e., pad open and pad short) are compared. Further, to develop a deep understanding about variations in error-terms values and in the S-parameters, a comprehensive 3D electromagnetic (EM) simulation study is performed. First, EM simulation analyses considering only one structure in simulation setup are performed to examine role of probe-to-probe and probe-to-substrate couplings. Later, EM simulation study is carried out to analyze the impact of the on-wafer neighbors, and the spatial position of the on-wafer neighbors. The EM simulation study shows a strong impact of the coupling of the DUT with the on-wafer neighbors, the spatial placement of the on-wafer neighbors, and the design of the reflect whereby the influence of the probe-to-probe coupling is partially masked by the aforementioned effects.

Numerical simulation study of free space method for measuring sample permittivity

The composition and performance of the material can be expressed by the permittivity. The paper introduces the measurement principle of free space method and TRL calibration principle, the calculation formula of the sample permittivity is theoretically analysed, a horn lens antenna is designed to simulate the emission of plane waves, and numerical simulation software is used for simulation and optimization. In the working frequency range, the voltage standing wave ratio of the antenna is less than 1.49, and the maximum gain is 21.8dB. A free space measurement system is established in the software to measure the sample permittivity with different thicknesses, and compare the calculated value with the actual value. The results show that the root mean square error of the real part is less than 5.3%, and the root mean square error of the imaginary part is less than 1.3%. The correctness and applicability of the formula for calculating the permittivity are also proved.

Calibration and Parameter Extraction of STT-MTJ Device at High Frequency by Using De-Embedding Approach Based on TRL Calibration

Spin-Torque-Transfer Magnetic Tunnel Junction (STT-MTJ) device shows wide applications in many important scenarios, including magnetic random access memory (MRAM), logic design, and high-frequency application. Its characterizations at the high frequency are studied intensively recently. In this article, the high-frequency properties of the STT-MTJ device are investigated thoroughly, including a de-embedding approach followed by an extraction procedure for removing the influences from the environment and the package. The de-embedding approach is performed on the STT-MTJ device operated at a high frequency, which can be used to calibrate its electrical characteristics by eliminating the environmental influence. After the calibration, the equivalent circuit for the MTJ device at high frequency can be set up, followed by the extraction procedure of the parasitic parameters of the high-frequency-equivalent-circuit. Combined with the extracted parameters, the equivalent circuit can be used for the simulation work with the MTJ device involved in the high-frequency operation.

Silicon Probe Measurement and Characterization in Sub-THz Range

We propose, investigate, and demonstrate a pure and simple dielectric probe operating in the sub-terahertz range with an example band of interest 190-220 GHz. High-resistivity silicon technology is deployed for this non-TEM mode probe development as it presents a viable low-loss material. A T-shape alignment dowel was used to integrate the silicon probe with the waveguide block. The probe can be used to measure and characterize the low permittivity-based dielectric waveguide transmission line and its building components free from the use of any transition structures and TEM-mode probes. For demonstration, the silicon probe was used to measure a substrate integrated image guide and its components in the range of 190-220 GHz. A substrate integrated image guide (SIIG)-based thru, reflect, and line (TRL) calibration kit was developed, and a two-tier TRL calibration was used to characterize the SIIG.

Schottky Diode Large-Signal Equivalent-Circuit Parameters Extraction for High-Efficiency Microwave Rectifying Circuit Design

A novel parameter extraction method for the Schottky diode’s large-signal equivalent-circuit model is proposed, and used to design high-efficiency microwave rectifying circuits. This method extracts the nonlinear SPICE parameters in the equivalent-circuit from measured I-V and C-V data, and the linear parasitic parameters from the broadband small-signal S-parameters. Moreover, it employs a de-embedding technology that adopts an equivalent circuit to remove the influence of the test fixture in the S-parameters measurement, thereby additional TRL calibration kits are not required. As a sample, large-signal equivalent-circuit parameters of the Schottky diode with model number MA4E1317 are extracted by the proposed method. Then it was used to design two Class-F microwave rectifying circuits working at 2.45 GHz and 5.8 GHz, respectively. Owing to the high accuracy of the extracted parameters by the proposed method, the simulation results such as the large-signal transient voltage waveforms across the diode agree well with the measured ones. Furthermore, two rectifying circuits exhibit very high rectifying efficiencies (e.g., 83.5% at 2.45 GHz and 82.1% at 5.8 GHz with 16.8 dBm input power).

Research on Calibration Algorithm of Non-coaxial RF Device Test Fixture

With the rapid development of RF devices, the requirements for their testing techniques are becoming stricter and stricter. Due to the large errors introduced by the test fixtures during the testing process, it is necessary for a suitable calibration algorithm to eliminate them. For eliminating errors, in this paper, the SOLT calibration algorithm and the TRL calibration algorithm are selected for mathematical derivation, and establish a mathematical model. According to the mathematical derivation of the calibration algorithm and the simulation using Matlab, consequently, the correctness of the SOLT calibration algorithm and the TRL calibration algorithm is verified. It is concluded that the SOLT calibration algorithm is more suitable for the low frequency bands test of the non-coaxial RF device test fixture, while the TRL calibration algorithm is more suitable for high frequency bands test of non-coaxial RF device test fixture.

Transition from rectangular waveguide to empty substrate integrated gap waveguide

Empty substrate integrated waveguide (ESIW) is a hollow SIW with its inner dielectric removed to achieve a reduced insertion loss. One of the drawbacks is the top and bottom covers need to be soldered to the middle substrate. Gap waveguide (GW) technology solves the contact issue utilising contactless electromagnetic band-gap (EBG) structures. Therefore, empty substrate integrated GW (ESIGW) is a transmission line having both advantages of ESIW and GW. In this Letter, a wideband transition from rectangular waveguide (RW) to ESIGW is presented. RW is firstly matched to reduced-height RW using E -plane stepped waveguides. Then, a short substrate integrated GW (SIGW) section is introduced between the reduced-height RW and the ESIGW. This section not only serves as an impedance matching component, it also connects the two sides of the ESIGW and maintains the integrity of the substrate. To broaden the bandwidth of the transition, a triangular dielectric is added at the end of the ESIGW. A Ka-band back-to-back prototype of the transition is designed and fabricated. In addition, TRL calibration is used to measure the transmission performance of the ESIGW. The measured results show that the transition works well over the entire Ka-band.

Comparison of On-Wafer TRL Calibration to ISS SOLT Calibration With Open-Short De-Embedding up to 500 GHz

Sub-mm circuit design requires accurate on-wafer characterization of passive and active devices. In industry, characterization of these devices is often performed with off-wafer short-open-load-thru (SOLT) calibration. In this paper, the validity of this characterization procedure above 110 GHz is investigated by an exhaustive study of on-wafer and alumina off-wafer calibration using measurement and electromagnetic (EM) simulation up to 500 GHz. The EM simulation is performed at two different levels, first at the intrinsic level of the devices under test for reference and afterward up to the probe level to simulate different standards used in the off-wafer calibration or in the on-wafer calibration in the presence of the probe. Furthermore, EM simulation data are calibrated with the same procedures and tools that are used in the measurement; therefore, it includes the probe-to-substrate coupling. In addition, precise EM model of a commercial impedance standard substrate is developed and used to perform the SOLT calibration. A good agreement is observed between measurement and EM modeling for the off-wafer calibration as well as for the on-wafer calibration. Results clearly highlight a limitation of alumina off-wafer methodology above 200 GHz for characterization of silicon-based technologies. Finally, a discussion is given on the pros and cons of the off-wafer and on-wafer methodologies.

Sensitivity analysis of multiport S‐parameter measurements due to nonideal TRL calibration standards

AbstractIn this paper, a detailed analysis of n‐port vector network analyzer measurement uncertainties due to nonideal standards for multiport through‐reflect‐line calibration is presented. By using the concept of general node equations, the error correction equation is simplified by the matrix operation; thus, a generalized formula for the deviations of the measured S parameters with respect to the error terms is derived, which can be implemented in further analysis of multiport measurement uncertainties applying arbitrary calibration method based on 4n‐term error model. The final expressions for the sensitivity coefficients of S parameters with simple and clear form provide a deeper understanding of error propagation mechanisms.

Determining the Complex Permittivity of Building Dielectric Materials using a Propagation Constant Measurement

<p>This paper presents a technique to determine the Dielectric constant and dielectric loss of the building dielectric materials using propagation constant measurements. The material sample is loaded in an X-band (8.5GHz-12.5GHz) rectangular waveguide and its two port S-parameters are measured as a function of frequency using a Vector Network Analyzer without TRL Calibration. The results obtained from samples of dielectric materials (Air, Cellular concrete and Wood) on the X-band frequencies show the validity of the proposed technique to determine the complex permittivity of the building dielectric materials on the X-band frequencies<em>.</em></p>

Millimeter-Wave On-Wafer TRL Calibration Employing 3-D EM Simulation-Based Characteristic Impedance Extraction

In this paper, we propose a method based on 3-D electromagnetic simulations, for the characteristic impedance extraction of transmission lines employed in TRL calibration, focusing on lines integrated in silicon technologies. The accuracy achieved with TRL calibrations using the proposed characteristic impedance extraction is benchmarked versus conventional approaches, with an emphasis on aluminum pads structures operating in the (sub) millimeter-wave range. The proposed method proves to be insensitive to common sources of error (i.e., large pad capacitance and inductive pad-to-line transitions), which affect the accuracy of characteristic impedance extraction based on measurements, especially as the testing frequency increases. First, direct on-wafer TRL calibrations are performed on uniform CPWs (i.e., with no pads discontinuities) to demonstrate how the proposed method performs as good as the calibration comparison method and outperforms calibration transfer approaches. Finally, the method is applied to a nonuniform CPW-based calibration kit, demonstrating how the proposed method provides accurate results, improving the calibration quality that can be achieved using the calibration comparison method when inductive pad-to-line transitions are present.

0.05–3 GHz VNA characterization of soil dielectric properties based on the multiline TRL calibration

We present a methodology for characterization of soil relative dielectric permittivity in the frequency range 0.05–3 GHz. Soil samples are placed in a measurement cell constructed out of a EIA coaxial transmission line, and then measured with a calibrated vector-network-analyzer. From these measurements the relative dielectric permittivity is obtained by use of a modified Boughriet algorithm. In order to calibrate the vector-network-analyzer directly at the EIA coaxial-transmission-line measurement planes, we use the multiline through-reflect-line method. This method, while providing superior vector-network-analyzer calibration accuracy, is also easy to implement since it uses only transmission lines with known lengths and a single unknown highly-reflective termination. The implemented calibration method was compared to a simplified approach that uses the standard SOLT calibration in Type-N reference planes, and then accounts for the Type-N/EIA adapters by removing their electrical delay. Experimental results for teflon and soil samples with different moisture content and salinity confirmed the validity of our approach.

An alternative method for verification of common mode absorption devices

Common Mode Absorption Devices CMADs are absorbing clamps required in the set ups for measurement of radiated disturbances. They should be verified with Vector Network Analyzers (VNAs), which unfortunately have coaxial ports. A CMAD can be connected to the VNA only if it is embedded in adapters. In the verification process, the clamp must be deembedded, i.e. the contribution of adapters must be extracted from the measured S-parameters. The Thru-Reflect-Line TRL calibration of the VNA is a suitable tool for that task, provided the necessary hardware and software facilities of the VNAs are available. If not, alternatives are required. In this paper, the alternative calibration is presented. The symmetry of adapters allows omitting the Reflect-step, providing this approach is preceded with the Short-Open-Thru-Match SOTM calibration. The method presented here consists of two steps only: the Thrustep in which adapters are cascaded face to face and the Linestep in which the rod line is inserted between the adapters. These two standards can have unknown S-parameters. Validation of the method consists in verification of the CMAD available on the market. There is entirely satisfactory convergence of the derived parameters with the data published by the manufacturer in the technical specification.

A Tensor-Based Extension for the Multi-Line TRL Calibration

The multi-line TRL (M-TRL) method is an accurate calibration method for S-parameter measurements that is based on the measurement of multiple transmission lines and their subsequent pairing. In this paper, an alternative is proposed for the line pairing process that underspans the M-TRL calibration. A tensor decomposition is used to process the measurements of all lines simultaneously and avoid the selection of a reference line as in the classical approach. Numerical and experimental results confirm the accuracy, the statistical efficiency, and the robustness of the proposed method.

On-Wafer Calibration Technique for High Frequency Measurement with Simultaneous Voltage and Current Tuning

This paper presents a novel on wafer calibration method for the measurement of radio RF passive components with R&S vector network analyzer (VNA) at RF and mm-wave frequency. This method has employed the high frequency structure simulator (HFSS) results along with multi-level optimizations to get the nominal values used for on wafer calibration. Multiline (Thru-reflect-line) TRL calibration standards fabricated on the same substrate are used with better accuracy. Measured results show that a thru line provides less than 0.015 dB insertion loss throughout the frequency range of 1GHz-67GHz. This result is much better compared to the results achieved by conventional Short-open-load-thru (SOLT) calibration and (Thru-reflect-line) TRL calibration using the available calibration substrates. Using this calibration technique, the phase variation of the thru line shows less than 3° at 67GHz which is much lower than 15° achieved by the conventional calibration methods. The measurement of the multi band characteristics of the RF passive components by simultaneous current and voltage application has also been demonstrated successfully.

Single-Flange 2-Port TRL Calibration for Accurate THz ${\rm S}$-Parameter Measurements of Waveguide Integrated Circuits

This paper describes a single flange 2-port measurement setup for S-parameter characterization of waveguide integrated devices. The setup greatly reduces calibration and measurement uncertainty by eliminating vector network analyzer (VNA) extender cable movement and minimizing the effect of waveguide manufacturing tolerances. Change time of standards is also improved, reducing the influence of VNA drift on the uncertainty. A TRL calibration kit has been manufactured and measurements are demonstrated in WR-03 (220–325 GHz).

Accuracy Improvement for Scattering-Parameters Evaluating of Microwave Coplanar Probe Using One-Port Two-Tier Multi-TRL Calibration Method

This paper presents a method improving accuracy for evaluating S-parameters (Scattering-parameters) of MCP (Microwave Coplanar Probe). This method may be named one-port two-tier Multi-TRL (Thru-Reflect-Line) calibration method. It measures two-port devices only at one port of VNA (Vector Network Analyzer). It decreases the random errors caused of cable movements and connecting times. This method is implemented with coaxial OSL (Open-Short-Load) and on-wafer TRL calibration kit. It directly calculates and removes the residual errors caused of coaxial OSL calibration kit imperfection. It significantly reduced system errors by using on-wafer TRL calibration kit. To verify the effectiveness of the proposed method, the measured S-parameters up to 50GHz of MCP configured with GSG-100 are given and discussed.

Limitations of On-Wafer Calibration and De-Embedding Methods in the Sub-THz Range

This paper investigates frequency limitations of calibration and de-embedding techniques for S parameter measurements. First, the TRL calibration methods are analysed and the error due to the probe movement when measuring the different line lengths is quantified, next the coupling between the probe-heads and the wafer surface is investigated and finally an upper frequency validity limit for the standard Open-Short de-embedding method is given. The measured results have been confirmed thanks to the use of an electro-magnetic simulator.

A New Calibration Algorithm Using Reference Materials for the Waveguide-Penetration Method

The waveguide-penetration method is a method to measure the electrical properties of materials. In this method, a cylindrical object pierces a rectangular waveguide through a pair of holes at the centre of its broad walls. Then, the complex permittivity and permeability of the object are estimated from measured S-parameters after TRL calibration. This paper proposes a new calibration algorithm for the waveguide-penetration method. Reference materials with known electrical properties are fabricated in cylindrical shapes to fit into the holes in the waveguide and are used as calibration standards. The algorithm is formulated using the property of equal traces in similar matrices, and we show that at least two reference materials are needed to calibrate the system. The proposed algorithm yields a simpler means of calibration compared to TRL and is verified using measurements in the S-band. Also, the error sensitivity coefficients are derived. These coefficients give valuable information for the selection of reference materials.

10 GHz 대역 기판 집적 도파관 대역 통과 여파기의 EM 시뮬레이션을 이용한 설계 및 제작

기판 집적 도파관(substrate integrated waveguide)은 높은 Q와 타 소자와 집적 가능성 때문에 최근 연구가 활발하다. 그러나 이의 특성은 기존 도파관 달리 해석적인 형태로 특성화되지 않아, 과거의 여파기 설계 방법으로는 정확한 설계를 하기가 어렵다. 본 논문에서는 최근 제시된 EM(Electro-Magnetic) 시뮬레이션을 기반으로 한 대역통과 여파기 설계 방법으로 10 GHz에서 10%의 대역폭을 갖는 3단 기판 집적 도파관 대역 통과 여파기를 3D EM simulator HFSS를 이용하여 설계하였다. 이 때 기판 집적 도파관은 마이크로스트립과 천이(transition)를 필요로 하는데, 여기서 기존 제안된 CPW(Coplanar Waveguide)대 SIW 천이 구조를 변형하여 적용하였다. 제안된 천이 구조는 천이 길이가 짧고 상용의 test fixture를 사용하여 TRL 측정이 가능하게 되어 있다. 제안된 2가지 천이 구조에 대하여 여파기를 제작하였으며, 제작된 여파기는 예상한대로 중심 주파수 10 GHz에서 10%의 대역폭약 12 dB 반사 손실, 0.8 dB 삽입 손실의 특성을 보였다. Recently, SIW(Substrate Integrated Waveguide) is intensively studied because of its high Q and easy integration with other devices. However, lacks of analytic characterization of SIW makes it difficult an accurate design of a SIW filter along the conventional filter design method. In this paper, two kinds of a three-stage 10 GHz SIW bandpass filter of fractional bandwidth 10% are designed using 3D EM simulator HFSS based on the recently presented EM filter design method. Two types of a modified CPW to SIW transition is proposed and employed as a SIW to microstrip transition necessary for measurement. The transitions provide an easy measurement with commercial test fixture by TRL calibration. The two proposed transitions are included in the SIW filters. The fabricated filters shows the center frequency of 10 GHz, fractional bandwidth 10%, a return loss of about 12 dB, and insertion loss of about 0.8 dB.