S-parameter characterization of high-speed interconnect components is prone to numerical, modeling, and/or measurement error, due in part to the sampled nature of the data. This is a problem in modern package design where extensive signal integrity simulations are required to validate a system's performance. This paper presents a new method of treating sampled S-parameter data where a criterion is developed to clearly state the minimum number of S-parameter frequency points required to adequately represent an analog physical system in the frequency domain. This criterion is akin to the Nyquist principle when sampling in the time domain. Based on this principle, the proper time domain representation of S-parameters can be obtained using the inverse Fast Fourier Transform (IFFT). However, in order to use the IFFT, the bilinear transformation is applied to the vector fitted Sparameters to place them in the z-domain. From the z-domain, the proper discrete impulse response is obtained. A lower bound, based on the discrete Heisenberg principle, is also offered to deal with frequency-time resolution of the S-parameters. The proposed method is successfully tested in measured and simulated S-parameter data. The usefulness of this method is to accurately represent the time domain behavior of the physical system S-parameter data, i.e. time delay causality, and therefore facilitates the applications of well-developed digital signal processing (DSP) techniques in S-parameter sampled data.
The broadband measurement of interconnects and on‐board devices requires the usage of test fixtures in order to connect to the measurement instrumentation. Proper assessment of the device performance requires removal of the effects of these test fixtures which is done using a de‐embedding procedure. Previous de‐embedding procedures such as Thru‐Reflect‐Line (TRL), Line‐Reflect‐Match (LRM) and other similar methods require the measurement of multiple standards. Alternatively, some methods such as thru de‐embedding techniques require measurement of one standard with explicit computation of only two or three of the four error terms. This is justified by using the sometimes questionable assumption of fixture reciprocity. Prior art also does not include derivation of all of the required equations. Proposed and explained in detail here is the usage of a 2x‐thru standard which is manipulated to derive complete fixture models without making assumptions about reciprocity or symmetry. Subsequently these models are mathematically removed from the indirect measurement, thus isolating the performance of the DUT. In contrast to prior art, this method uses only one standard instead of three, and it computes all four terms to make a complete fixture model. Several test cases are presented which illustrate the accuracy and validity of the 2x‐thru method for broadband applications.
In this paper, a new adaptive equalization technique of a multi-gigabit channel is proposed. This approach calculates the voltages probability density functions of the received signal; and based on the spread of the PDF curves, weights of FIR filters are updated. The algorithm was tested in a Tyco XAUI-FR4 backplane.
A fast and accurate characterization method of differential via holes is presented based on the equivalent circuit extraction technique. A 3-D model of differential via holes is created and simulated using a full wave solver and the results are compared with the equivalent circuit model using Advanced Design System software. Results presented validate the proposed approach.
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