Youri V. Tretiakov

On-chip SiGe transmission line measurements and model verification up to 110 GHz

On-chip microstrip transmission lines have been measured on-wafer from below 1 GHz up to 110 GHz. Using different pad de-embedding techniques as well as a technique based on two transmission lines of different length, the characteristic transmission line parameters have been accurately determined. The results are compared against simulation results from an electromagnetic full-wave solution and the parametric IBM model which is available in the technologys design kit.

On-chip interconnect-aware design and modeling methodology based on high bandwidth transmission line devices

This paper expands the on-chip interconnect-aware methodology for high-speed analog and mixed signal design, presented in D. Goren et al. (2002), into a wider class of designs, including dense layout CMOS design. The proposed solution employs a set of parameterized on-chip transmission line (T-line) devices for the critical interconnects, which is expanded to include coplanar structures while considering the silicon substrate effect. The generalized methodology contains treatment of the crossing line effects at the various design stages, including two way interactions between the post layout extraction tool and the T-line devices. The T-line device models are passive by construction, easily migratable among design environments, and allow for both time and frequency domain simulations. These models are verified by S-parameter measurements up to 110GHz, as well as by EM solver results. It is experimentally shown that the effect of properly designed discontinuities is negligible in most practical cases. The basic on-chip T-line methodology is being used extensively for numerous high-speed designs.

A new on-wafer de-embedding technique for on-chip rf transmission line interconnect characterization

Absfracf This paper introduces a new de-embedding method for on-chip RF transmission line characterization. The new technique allows subtraction of pad parasitics based on measurements of only two LI=L and Lz=N.L (N being a discrete number) long transmission lines with attached measurement pads. No dummy “open”, “short” and “thru” devices are required. The new method has also been extended for the case when Lz#N.L, and only L,, L2 and AL= L,-L, long interconnects with attached pads are available on the test wafer. The proposed methodology has been compared with several well-known de-embedding approaches (“thru”, “open-short” aed “short-open“) and with simulation results from the industry standard electromagnetic solver (lE3D) for de-embedding of on-chip interconnects at frequencies up to 70GHz. Index Terms -Transmission Line interconnect, on-wafer measurement, S-parameters, de-embedding.

Smooth local cosine based Galerkin method for scattering problems

The smooth local trigonometric (SLT) functions are employed as the basis and testing functions in the Galerkin based method of moments (MoM), and sparse impedance matrices are obtained. The basic idea of SLT is to use smooth cutoff functions to split the function and to fold overlapping parts back into the intervals so that the orthogonality of the system is preserved. Moreover, by choosing the correct trigonometric basis, rapid convergence in the case of smooth functions is ensured. The SLT system is particularly suitable to handle electrically large scatterers, where the integral kernel behaves in a highly oscillatory manner. Numerical examples demonstrate the scattering of electromagnetic waves from two-dimensional objects with smooth contours as well as with sharp edges. A comparison of the new approach versus the traditional MoM and wavelet methods is provided.

Parasitic modeling and noise mitigation in advanced RF/mixed-signal silicon germanium processes

The potential for highly integrated radio frequency (RF) and mixed-signal (AMS) designs is today very real with the availability cost-effective scaled silicon-germanium (SiGe) process technologies. However, the lack of effective parasitic modeling and noise mitigation significantly restrict opportunities for integration, due to a lack of computer-aided design solutions and practical guidance for designers. This tutorial paper provides a broad in-depth coverage of the key technical areas that designers need to understand in estimating and mitigating IC parasitic effects. A detailed analysis of the parasitic effects in passive devices, the interconnect (including transmission line modeling) and substrate impedance, and isolation estimation is presented-referencing a large number of key publications in these areas.

ON SAMPLING-BIORTHOGONAL TIME-DOMAIN SCHEME BASED ON DAUBECHIES COMPACTLY SUPPORTED WAVELETS

The multi-resolution time domain (MRTD) technique for electromagnetic field equations was proposed by Krumpholz, Katehi et al., using Battle-Lemarie wavelets. The basis principle behind the MRTD is the wavelet-Galerkin time domain (WGTD) approach. Despite its effectiveness in space discretization, the complexity ofthe MRTD makes it unpopular. Recently, the WGTD was significantly simplified by Cheong et al. based on the approximate sampling property ofthe shifted versions ofthe Daubechies compactly supported wavelets. In this paper, we provide a rigorous analysis ofthe MRTD, employing positive sampling functions and their biorthogonal dual. We call our approach as the sampling biorthogonal time-domain (SBTD) technique. The introduced sampling and dual functions are both originated from Daubechies scaling functions of order 2 (referred as to D2), and form a biorthonormal system. This biorthonormal system has exact interpolation properties and demonstrates superiority over the FDTD in terms ofmemory and speed. Numerical examples and comparisons with the traditional FDTD results are provided.

MALVAR WAVELET BASED POCKLINGTON EQUATION SOLUTIONS TO THIN-WIRE ANTENNAS AND SCATTERERS

Malvar wavelets are often referred to as smooth local cosine (SLC) functions. In this paper the SLC functions are employed as the basis and testing functions in the Galerkin-based Method of Moments (MoM) for the Pocklington equation of thin-wire antennas and scatterers. The SLC system has rapid convergence and is particularly suitable to handle electrically large scatterers, where the integral kernel behaves in a highly oscillatory manner. Numerical examples demonstrate the scattering of electromagnetic waves from a thin-wire scatterer as well as wave radiation from the gull-shaped antenna. A comparison of the new approach versus the traditional MoM is provided.

Coifman wavelets in electromagnetic wave scattering by a groove in a conducting plane

Scattering of electromagnetic waves from a groove in an infinite conducting plane is studied using the Coifman wavelets (Coiflets) under the integral equation formulation. The induced current is expressed in terms of the known Kirchhoff solution plus a localized correction current in the vicinity of the groove. The Galerkin procedure is implemented, employing the Coiflets as expansion and testing functions to find the correction current numerically. Owing to the vanishing moments, the Coiflets lead to a one-point quadrature formula in O(h5), which reduces the computational effort in filling the impedance matrix entries. The resulting matrix is sparse, which is desirable for iterative algorithms. Numerical results show that the new method is 2 to 5 times faster than the pulse based method of moments.

Vertically-stacked on-chip SiGe/BiCMOS/RFCMOS coplanar waveguides

This paper presents a new on-chip transmission line interconnect structure which offers the potential of superior return and insertion loss characteristics compared to the equivalent standard transmission line device. Conventional on-chip coplanar waveguides (CPW) and differential pairs are routed in a single metal layer in the chips metal-dielectric stack. The vertically stacked coplanar waveguide (PW) transmission lines presented here consist of metal lines on multiple metal levels connected by continuous via bars. The additional cross-sectional area of the VCPW topology decreases interconnect resistance while the increased effective device thickness increases capacitance to neighboring ground return lines leading to a characteristics impedance reduction.

Malvar wavelets for thin-wire antennas and scatterers

We apply smooth local cosine (SLC) functions to integral equations to solve thin-wire scattering and radiation problems. Numerical examples of a thin-wire scatterer and antenna are presented. The results are compared with those obtained by using the standard pulse-based MoM. It is noticed that the use of the fast discrete cosine transform DCT-IV can drastically reduce computation time and increase the accuracy of numerical calculations.