In-fixture calibration of an S-parameter measuring system by means of time domain reflectometry

We present a technique which resorts to the time domain capabilities of a vector network analyzer and to the network synthesia tools, in order to perform an in-fixture calibration of the S-parameter measurement system directly to the ports of the device under test. The effects of the customer's non ideal fixtures can be removed without requiring the insertion of standard components or particular loads, which can affect the calibration efectiveness. The inaccuracies due to the precision of the actual loads and to the connection repeatability are also avoided. Some simulation reeults demonstrate the very good capability of the technique. Experimental tests were also carried out on an actual microstrip transistor fixture, showing a very satisfactoty launcher modeling and de-embeddin

Recent Advances in Real-Time Load-Pull Systems

In this paper, some of the latest advances in real-time load-pull technologies will be described. A recently introduced ultralow-loss directional coupler, which has been designed and realized by the authors, provides a number of advantages when used in load-pull test sets. This device has been called the load-pull head. The new ultralow-loss load-pull head can transform any passive precalibrated load-pull system into an easily calibrated and accurate real-time load-pull test set, without losing highreflection- coefficient capabilities. Moreover, if used to realize an active loop, the load-pull head reduces the risks of oscillations and the amount of the loop amplifier output power. As an example application, measurements with a passive real-time load-pull setup of a 30-W laterally diffused MOS (LDMOS) transistor are presented. Furthermore, some advice to bypass the remaining unavoidable losses due to probes and cables is given.We will show, with measurements and with very simple calculations, that the combined use of load-pull heads, a passive tuner, and an active loop not only boosts the available ΓL but also decreases the loop amplifier output power, with a sensible reduction in the overall cost of the syste

Time domain reflectometry applied to MMIC passive component modeling

The time domain facilities of a network analyzer, combined with the tools of network synthesis, were recently used for experimental modeling of discontinuities in an S-parameter measurement set, so as to allow the instrument calibration directly to the ports of the device under test. The technique proved to be very useful in those cases where the discontinuities, that lie before the unknown device, cannot be isolated by the usual calibration methods, and therefore, since network synthesis deals only with frequency domain information, it is impossible to optimize the model's parameters, since they are affected by errors due to discontinuities. This paper describes a procedure which allows to isolate the response of the device under test, and to derive its complete model; when it to reach a reasonable accuracy it gives anyway a topology, which is a good starting point for other optimization routines that can be used for obtaining a better match, on a broad frequency band. This can be accomplished by optimzing the first approach topology to which other circuit elements have been added, so as to take into account second order effects especially at the higher frequencies. The technique was applied to model and characterize passive discrete components used in MMIC. The experimental results show the validity of the approac

A simple NWA calibration algorithm based on a transfer standard

A new two-port network analyzer (NWA) calibration technique is here presented. It uses a single two-port transfer standard plus a known reflectance to perform the calibration process. The transfer standard device has to be previously fully characterized with a traceable NWA. The technique here proposed uses less standards than any other up today calibration algorithm, which, on the contrary, requires at least three different devices. The paper presents the calibration algorithm along with some on-wafer experimental results which compare the new solution with a more traditional technique

Multiport network analyzer self-calibration: a new approach and some interesting results

A new approach to multiport network analyzer calibration is here presented. This solution exploits the redundancy of multiple standards connections in order to perform a multiport self-calibration. The method allows to use also partially or even fully unknown devices as standards. The algorithm is independent from a particular standard sequence. By this new approach, the user can tailor the known or unknown standard sequence to best fit the measurement needs and test set constrains. As an example we proved that the calibration of a three-port NWA can be carried out by the insertion of three known reflections at one port of the test-set, plus three connections of the same fully unknown two-port device

Design and realization of an on-wafer two port transfer standard

Among the different techniques for the network analyser calibration, the authors recently introduced the NR procedure based on the concept of transfer standard, characterised by primary laboratories. The paper presents the theory assumed to properly design that standard and some experimental results to verify the accuracy obtained by this calibration

Comparison between a vector multiport network analyzer and the national S-parameter measurement system

A multiport vector network analyzer based on a new calibration concept, has been compared with the P-port S-parameter National measurement system at IENGF. The measurements were performed on precision 7 mm standard components and exhibited an optimum agreement. These results open the possibility to use the new multiport network analyzer for certification measurements of multiport device

Accuracy of a multiport network analyzer

The accuracy of a multiport vector network analyzer, which uses a new calibration concept, has been compared with a 2-port network analyzer that implements the classical TRL procedure. The accuracy assessment is based on the analysis of the error propagation due to the connectors repeatability, both of the used standards and the measurands. The comparison, performed in the 2-18 GHz band on devices fitted with APC-7 mm connectors, proved the high accuracy reached by a multiport system which can qualify for metrological applications

Accuracy Improvement of Real-Time Load-Pull Measurements

This paper describes a new procedure aimed to improve the effectiveness of real-time load-pull calibration. Loadpull measurement accuracy is strongly affected by calibration residual uncertainty. The novel methodology reduces this uncertainty contribution by means of error terms optimization. The proposed method has been tested with simulations and applied to actual measurement data. Considerable improvements have been achieve

Testing devices under different source impedances: a novel technique for on-line measurement of source and device reflection coefficients

This paper describes a new approach for fast and accurate determination of the source reflection coefficient in microwave source-pull measurements. To the authors' knowledge, this is the only technique that allows the simultaneous measurement of the source and the DUT gammas. A traditional vector network analyzer is used as a three-channel receiver. The calibration procedure is based on a new reflectometer model that extends the traditional error box concept. Experimental results are presented and compared to data obtained with traditional techniques