Frank Wiedmann

A new robust method for six-port reflectometer calibration

A new robust method for finding the parameters of Engens six-port-to-four-port reduction algorithm for six-port reflectometer calibration has been developed. Like other previously published methods, it uses a minimum of five loads with an unknown but constant absolute value of the reflection coefficient and unknown but well-distributed phases. However, the quality of the parameter estimates is improved, especially in noisy environments, by efficiently eliminating cases in which these earlier methods may become ill-conditioned. The new method has been used successfully to calibrate a newly developed six-port reflectometer in GaAs MMIC technology working between 1.3 GHz and 3.0 GHz.

Two new six-port reflectometers covering very large bandwidths

This paper presents two new structures for six-port reflectometers with very large operating bandwidths of more than three decades, using a combination of lumped reflectors and transmission lines. Circuits working over a range of 2 MHz to 1300 MHz and 2 MHz to 2200 MHz have been built using inexpensive passive surface mount elements and Schottky detector diodes. Comparing results obtained from the new proposed structures with those obtained from a commercial network analyzer showed a worst case absolute value of 0.020 for the complex difference between the measured reflection coefficients. A convenient calibration procedure, for the entire band, is proposed using three standards and four approximately known loads.

New structure for a six-port reflectometer in monolithic microwave integrated-circuit technology

This paper presents a new structure for a six-port reflectometer which due to its simplicity can be implemented very easily in monolithic microwave integrated-circuit (MMIC) technology. It uses nonmatched diode detectors with a high input impedance which are placed around a phase shifter in conjunction with a power divider for the reference detector. The circuit has been fabricated using the F20 GaAs process of the GEC-Marconi foundry and operates between 1.3 GHz and 3.0 GHz.

Microwave Measurement using Wheatstone's Bridges

This paper presents the design of Monolithic Six-Port Module MSPM with resistive bridges. It shows how these simple structures may act as directional resistive couplers. Final MMIC circuit includes six-port junction and matched MESFET detectors covering an area of 1.2 mm2 in the frequency range 100 MHz to 3 GHz. The MSPM was bonded in a MIC structure with output coaxial connectors or inside the tips of a probe station. In this last case, the MSPM acts as an active probe. Experimental results obtained using a commercial network analyzer and our measurement system are in good agreement.

New structure for a six-port reflectometer in MMIC technology

This paper presents a new structure for a six-port reflectometer which due to its simplicity can be integrated very easily in MMIC technology. It uses non-matched diode detectors with a high input impedance that are placed around a phase shifter. The circuit has been fabricated by the foundry GEC-Marconi and operates between 1.4 and 2.5 GHz.

New structures for six-port reflectometers covering very large bandwidths

This paper presents two new structures for six-port reflectometers with very large operating bandwidths of more than three decades, using a combination of lumped reflectors and transmission lines. Circuits working over a range of 2-1300 MHz and 2-2200 MHz have been built using inexpensive passive surface mount elements and Schottky detector diodes. Comparing results obtained from the new proposed structures with those obtained from a commercial network analyzer show a worst case absolute value of 0.020 for the complex difference between the measured reflection coefficients. A convenient calibration procedure, for the entire band, is proposed using three standards and four approximately known loads.

Cyclostationary Stochastic Jitter Measurement Method With Uncertainty Prediction

This paper presents a completely new approach to measure the jitter at the output of a sample-and-hold circuit. A cyclostationary stochastic process is used to model the entire noise of the measurement system. This approach relies on the calculation of a cyclostationary variance, representing a complete description of the noise of the measurement system. This provides the basis for conducting powerful analyses of how the various noise sources contribute to the cyclostationary variance, enabling the user to gain a deep insight into the noise behavior of the system. A new jitter estimator is derived that provides some new and unprecedented features. First, it is robust against the second harmonic of the input signal, and second, it allows for the elimination of cyclostationary noise contributed by the data acquisition device. A stochastic model of the method is derived and a thorough analysis of the uncertainty of the proposed estimator is presented. This results in a formula that allows for the prediction of the measurement uncertainty and another formula that allows for the calculation of the required number of samples in order to meet a given uncertainty. The method proved to be accurate in Monte Carlo simulations and in measurements as well. A jitter in the range of 22 fs out of a 10-GS/s sample-and-hold integrated circuit was successfully measured with a standard deviation of 230 as.