Characteristic impedance extraction using calibration comparison (original) (raw)
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Thru-line (TL) calibration technique for on-wafer measurement
Millimeter-wave CMOS RF circuits have been received substantial attention in recent years, motivated by the advancement of CMOS process. Figure 1 shows on-wafer measurement using probes, which is common in research and development. De-embedding is necessary to remove the effect of pads in on-wafer measurement of RF circuits. Thru-Reflect-Line (TRL) calibration [1] and/or de-embedding method using open and short patterns [2] are often used. The authors applied the Thru-Line (TL) calibration method [3] to remove the effect of pads in the measurement of RF circuits on a Si CMOS substrate. TL calibration requires two patterns (thru and line) while TRL calibration requires three patterns (thru, reflect and line). TL calibration can characterize both pads under the assumption that both pads have the same characteristics while TRL calibration can not characterize pads. In this paper, the effectiveness of the TL calibration is investigated for the deembedding of the influence of pads in on-wafer measurement.
Base-band impedance control and calibration for on-wafer linearity measurements
ARFTG 63rd Conference, Spring 2004
This paper introduces a direct and accurate method for controlling and measuring the on-wafer device terminations at the base-band / envelope frequency, using an extension of a conventional network analyzer setup. The base-band impedance can be adjusted manually as well as electronically and is able to (over)_compensate the losses in the measurement setup. This facilitates on-wafer base-band terminations ranging from negative to high Ohmic values. The proposed measurement techniques are particularly useful when characterizing active devices for their linearity.
IEEE Transactions on Microwave Theory and Techniques, 2017
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-toline transitions are present.
A New Characterization and Calibration Method for 3-dB-Coupled On-Wafer Measurements
IEEE Transactions on Microwave Theory and Techniques, 2000
A two-port vector network analyzer (VNA) can be used for measuring the differential-mode (or common-mode) -parameters of an integrated circuit by combining on-wafer probes with 3-dB-coupling baluns (or power splitters). In such a measurement setup, the error networks from each port of the VNA to the device-under-test are three-port rather than the conventional two-port. This paper proposes a new set of an impedance standards and algorithm that can efficiently extract the full nine mixed-mode -parameters of the three-port error network. For differential-mode measurements, the four differential-mode -parameters are used for the calibration and the remaining five common-and cross-mode -parameters are used for evaluating their associated measurement errors. By a minor variation, the proposed method can be used for characterizing the full nine mixed-mode -parameters of the 3-dB-coupler embedded probe itself, providing a valuable tool in its development stage. The proposed method uses a pseudoinverse of an overdetermined matrix, by which it becomes tolerant to errors that occur when measuring the impedance standards.
Characteristic impedance extraction of embedded and integrated interconnects
The European Physical Journal Applied Physics, 2011
In this paper we extract the characteristic impedance of Back-End Of Line (BEOL) interconnections from radio frequency (RF) scattering parameter measurements. Quantification of the electric interconnection performance on a broad frequency band requires a good knowledge of the characteristic impedance Z c and the propagation exponent γ. This propagation exponent is easily obtained by measuring two interconnections with different lengths. However, because of the complex test structure with mismatched ports where interconnections are embedded, the extraction of Z c from scattering parameter measurements remains challenging. To solve this problem, we propose an approach based on the Winkel method without using simplified hypotheses generally applied. Limits of validity for our deembedding procedure to extract characteristic impedance are also analyzed.
2020
This article proposes a novel impedance standard substrate, as known as calibration kit, 17 for the calibration using radio frequency (RF) and microwave probes, especially the through 18 substrate which is able to calibrate not only the conventional horizontal but also the vertical 19 interconnects on the basis of the short-open-load-through (SOLT) standardized calibration 20 approach. In the measurement of a vertical connection where the probing ports are located on the 21 opposite surfaces of devices, a location change or rotate with the probes is required after the 22 calibration based on the conventional coplanar kit which only allows the probing in the same 23 plane. The location change or rotation of the probes and corresponding connected cables 24 inevitably affects the precision of the calibration since the probes and cables are sensitive to the 25 surroundings. Our proposed calibration kit can overcome the aforementioned shortcomings, and 26 the comparison of calibrated res...
An Advanced Calibration Method for Probe Leakage Correction in On-Wafer Test Systems
IEEE Transactions on Microwave Theory and Techniques
This article presents an advanced calibration method for solving the error terms due to probe-probe leakage in an on-wafer test system. A new 12-term error model for the on-wafer test system including vector network analyzer (VNA), frequency extenders (if there are any), cables/waveguides, probes, probe contact pads and probe-probe leakage is introduced. A two-step calibration process and an algorithm with four on-chip calibration standards including one undefined Thru, two pairs of undefined symmetrical Reflects such as Open-Open and Short-Short pairs and a pair of known Match loads has been developed. In addition, an improved circuit model for the Match load is proposed for enhanced accuracy. The calibration method has been tested on a mismatched attenuator for the frequency range between 0.2 GHz and 110 GHz and the results are compared with numerical simulation and existing calibration methods. It's shown that the attenuator's |S11| is more consecutive and |S21| has been improved by up-to 1.7 dB. It is evident that the proposed calibration method has a simpler calibration process and less stringent requirements on calibration standards which are key for on-wafer system calibration at millimeter-wave and terahertz frequencies. More importantly, the new calibration method is more suitable for measurements in which DUTs have variable lengths. Index Terms-Calibration, load circuit model, on-wafer scattering parameter, probe leakage. I. INTRODUCTION LL S-parameter test systems that are used to measure microwave devices such as antennas, filters, couplers, etc. [1-4] have residual system errors which must be calibrated out with an appropriate calibration method and some calibration standards before being used.
Influence of Microwave Probes on Calibrated On-Wafer Measurements
IEEE Transactions on Microwave Theory and Techniques, 2019
On-wafer probing with ground-signal-ground (GSG) probes contributes a variety of side effects, which are related to the measured line type, the carrier material, the layout with the neighboring structures, and the probe. Thus, the size and shape of the probe together with the measured line type and the neighboring circuits influence the quality of the calibrated measured result. This paper presents corresponding results when using the multiline-thru-reflect-line (mTRL) calibration, which is commonly accepted as one of the most accurate calibration algorithms, and concentrates on the impact of the probe construction together with neighboring elements, for the most common planar transmission lines, coplanar waveguides (CPWs), and thin-film microstrip lines (TFMSLs). For the first time, design guidelines with regard to the layout, the measurement environment, and the construction of the probes are given.
International Journal of RF and Microwave Computer-Aided Engineering, 2006
In this work, a resistor standard is introduced into our previously proposed numerical thru-reflect-line (TRL) calibration procedure in order to determine the characteristic impedance of the line standard of calibration on the basis of a deterministic method of moments (MoM) algorithm. A comprehensive analytical derivation is presented with regards to electrical properties of such a resistor standard in comparison to other standards. In addition, an error analysis is detailed, which reveals correlations of characteristic parameters in connection with equivalent circuit model development from the conversions from fieldbased S-parameters to circuit-based Y-or Z-parameters. Interesting properties and criteria are derived, allowing accurate parameter extractions. To validate the proposed numerical TRL calibration procedure with this new resistor standard concept and the developed error analysis, the characteristic impedance of a microstrip line is extracted from a commercial software. In addition, a further example with microstrip discontinuity is shown and the effectiveness of the proposed technique is verified.
Calibration Techniques for Millimetre-wave On-wafer S-parameter Measurements
2019
Accurate characterisation of S-parameters (scattering parameters) at chip level is of great importance to the development of next generation electronic devices. Such measurements are usually carried out on a Vector Network Analyzer (VNA), subject to an on-wafer calibration. Calibration techniques play a key role in determining the accuracy of on-wafer measurements. This paper is intended to provide an overview of conventional calibration techniques, including TRL (Thru, Reflect, Line), Multi-Line TRL, SOLT (Short, Open, Load, Thru), LRM (Line, Reflect, Match), and LRRM (Line, Reflect, Reflect, Match). Advantages and limitations of these different calibration techniques are discussed briefly and summarised. This paper also gives an insight into important factors that influence on-wafer measurement quality. These factors include design of calibration standards, testing environment (boundary and nearby structures), probes pitch sizes, etc.