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This paper presents a technique that optimizes LC-tank CMOS voltage-controlled oscillators (VCOs) by minimizing the product of phase noise and power consumption. Moreover, it shows that the minimum depends on the tank's quality factor Q, the device noise coefficient [gamma], and the ratio between the maximum oscillation amplitude and supply voltage [alpha]. Prototypes, realized in a 0.35-[mu]m process, show the following performances: --122.5 dBc/Hz at 600 kHz from a 1.9-GHz carrier, with 2.V supply voltage and 1-mA current consumption. The VCO can be tuned between 1.8-2.4 GHz, when the varactor control voltage is varied between 0-3.5 V. In the proposed realization, the tank is made of a metal-oxide-silicon varactor (operated between accumulation and deep depletion) and a bond-wire inductor, realized connecting two pads to a package frame lead to be compatible with the production environment. Index Terms--CMOS integrated circuits, LC oscillators, phase noise, radio frequency, varactors, voltage-controlled oscillators.

In this paper, an efficient absorbing boundary condition (ABC) constructed in the Z-transform domain [i.e., Z-transform-based absorbing boundary conditions (Z-ABCs)] for the three-dimensional symmetrical condensed-node transmission-line matrix method is presented. Numerical results indicate that the Z-ABCs show better performance than the conventional Higdon's ABC in suppressing instability caused by spurious modes. Index Terms--3-D SCN-TLM, Z-ABCs.

This paper presents a new technique for the convergence acceleration of a large class of series often arising in electromagnetic problems. The technique is based on the recursive application of the integration-by-parts technique to discrete sequences, thus the given name of the 'summation-by-parts' technique. It is shown that the new technique greatly enhances the convergence rate of the series treated, and very small relative errors are obtained by performing a few simple operations. The new technique is applied to the efficient numerical calculation of the Green's functions in a parallel-plate waveguide. Index Terms--Convergence acceleration, modal expansions, shielded Green's functions.

An improved automatic extraction technique for determination of the element values of an InP heterojunction-bipolar-transistor small-signal T-model is presented. Numerical optimization is shown to yield reproducible and physically relevant results when using a suitable figure-of-merit. The outcome of such an extraction is displayed for a range of operation points and the resulting bias dependencies of the element values is shown to be in good agreement with theoretical effects. The technique is further used to validate the quality of the extraction itself by showing a significant sensitivity to a deliberate error in the value of each element. Index Terms--HBT, InP, numerical parameter extraction.

The interface loss mechanisms of coplanar waveguides (CPWs) on silicon with an Si[O.sub.2] isolation layer are investigated. The total losses of straight CPW lines of 7.5-mm length are measured between 45 MHz and 40 GHz and the interface contribution is extracted from that by its bias dependence. The interface losses depend on bias voltage and on the oxide quality. With an optimal bias voltage, the attenuation of a CPW with an unpatterned oxide layer always achieves a minimum. With bias between the fiat-band voltage [V.sub.FB] and threshold voltage [V.sub.T] (depletion region), the interface losses are negligible. For high quality oxides ([V.sub.T] around 0 V), very low attenuation was obtained without any bias. Index Terms--Bias-dependent attenuation, coplanar waveguide, depletion, interface losses, oxide, silicon, threshold voltage.

A 1.9-GHz monolithic superheterodyne receiver front-end with 300-MHz IF on-chip tunable image-reject filter and voltage-controlled oscillator (VCO) is presented. Two versions of the receiver were fabricated on a 0.5-[mu]m bipolar process and compared to a previously fabricated version with an off-chip VCO. The two versions are identical, except for the fact that the 2.2-GHz VCO was realized with and without ground-shielded inductors. The receiver that used ground-shielded inductors had a conversion gain of 25.6 dB, a noise figure of 4.5 dB, a third-order input intercept point (IIP3) of -- 19 dBm, an image rejection of 65 dB, and a phase noise of -- 103 dBc/Hz at 100-kHz offset. The receiver drew 32.5 mA from a 3-V supply and had a die area of 2.1 mm x 1.7 mm. The local-oscillator-IF isolation improved compared to the previously fabricated front-end with an off-chip VCO. Index Terms--Inductors, integrated circuit design, MMIC receivers, notch filters, voltage-controlled oscillator.

Efficient control of millimeter-waves in a slot line on an Si and GaAs substrate is discussed both theoretically and experimentally. The spectral-domain method is used to estimate the propagation and the attenuation constants in the slot line with the density of the optically induced plasma as a parameter. Experiments in the millimeter-wave range of 35-50 GHz are carried out using high-resistivity Si and GaAs wafers with the dimension of 15 mm x 30 mm x 600 [mu]m. The slot-width could be varied from 0.5 to 2 mm. The attenuation of millimeter waves by over 20 dB can be controlled by optical means using light-emitting diodes with 870-nm wavelength and 68-mW optical power. The experimental results agree considerably well with the theory. The response of millimeter waves with pulsed optical illumination is also examined using a high-power laser diode of 20-W optical power and a pulsewidth less than 100 ns. High-speed response due to optically induced plasma is confirmed for the slot line on GaAs substrate. Index Terms--GaAs, millimeter waves, optical control, Si, slot line, solid-state plasma.

A method to determine the heterojunction bipoloar transistor (HBT) equivalent-circuit elements without numerical optimizations is presented. It is based on the extraction of nine analytical expressions, which are referred to here as 'blocks.' The model elements are extracted using certain blocks for some of them and three nonlinear equations derived from a combination of four expression blocks for some others. The base and collector resistances can be determined at each bias point. The method is validated treating the on-wafer HBTs. Index Terms--Analytical method, heterojunction bipolar transistor, parameter extraction.

This paper compares partial waves approximating a surface leaky wave on a uniplanar transmission line with substrate surface waves supported by its substrate. It is shown that their field distributions and the propagation constants differ. These differences increase with rising leakage constant, and with the growing distance of the corresponding pole of the Green function from the real axis on the spectral variable complex plane. The reported findings are demonstrated on the slotline. Index Terms--Leaky waves, printed-circuit lines, slotlines.

In this paper, a brief description of the line-integral formulation of mode matching is recalled, and the analysis is extended to the case of a TEM mode, normalization integrals, and degenerate eigenvalues. Index Terms--Mode matching, waveguide scattering problems.