M. Fernandez-Barciela

A simplified broad-band large-signal nonquasi-static table-based FET model

In this paper, a simplified nonquasi-static table-based approach is developed for high-frequency broad-band large-signal field-effect-transistor modeling. As well as low-frequency dispersion, the quadratic frequency dependency of the /spl gamma/-parameters at high frequencies is taken into account through the use of linear delays. This model is suitable for applications related to nonlinear microwave computer-aided design and can be both easily extracted from dc and S-parameter measurements and implemented in commercially available simulation tools. Model formulation, small-signal, and large-signal validation will be described in this paper. Excellent results are obtained from dc up to the device f/sub T/ frequencies, even when f/sub T/ is as high as 100 GHz.

Direct extraction of nonlinear FET Q-V functions from time domain large signal measurements

The authors present a simple and accurate procedure for the direct extraction of the quasi-static FET model nonlinear charge functions from large signal measurements. The method is based on the proper use of a vector nonlinear network analyzer (VNNA) with load-pull facilities. To our knowledge, these results show for the first time a direct procedure to extract the nonlinear charges of a FET using a very reduced number of large signal measurements.

An optimized 25.5-76.5 GHz PHEMT-based coplanar frequency tripler

This letter presents an optimized single-stage MMIC tripler with W-band output frequency (76.5 GHz). The circuit is based on an 0.15 μm gate-length AlGaAs/InGaAs/GaAs PHEMT. By using a class AB transistor bias point and carefully selecting its input and output terminations, a high conversion gain of -4.3 dB for an 8.5 dBm input signal and a saturated output power of 7 dBm have been obtained. To our knowledge, these results represent the best performance reported up to date for an active frequency tripler with W-band output frequency.

Coplanar pHEMT MMIC frequency multipliers for 76-GHz automotive radar

For 76-GHz transmitters, two coplanar monolithic microwave integrated circuit (MMIC) frequency multipliers were realized in a 0.15-μm pHEMT technology on GaAs. A 38/76-GHz frequency doubler achieved a state-of-the-art output power of 10 dBm for a 16-dBm input signal and a maximum conversion gain of -4 dB. For a 19/76-GHz frequency quadrupler, a high conversion gain of -7.5 dB for an input power of 8 dBm and a saturated power of 4 dBm was demonstrated. To our knowledge, this is the first reported W-band one-stage frequency quadrupler based on HEMT technology.

HBT small signal T and /spl pi/ model extraction using a simple, robust and fully analytical procedure

A simple and fully analytical procedure is proposed in this paper for the direct extraction of the HBT small signal equivalent circuit model, whether it be the T- or hybrid /spl pi/-topology, from DC and single-frequency s-parameter measurements. DC data is required since it is possible to show that direct extraction from single frequency s-parameters is not possible, without prior knowledge of one parameter. The extraction procedure developed is based on the prior knowledge of dc current gain, /spl beta//sub 0/. Excellent results have been obtained when applied to InGaP/GaAs and InP based HBTs.

38/76 GHz PHEMT MMIC balanced frequency doublers in coplanar technology

Two 38/76 GHz push-push frequency doublers have been realized in a 0.15 μm GaAs PHEMT technology. The circuits are based on different 180/spl deg/ power divider structures: a Lange coupler followed by a 90/spl deg/ transmission line, and a balun. The circuits achieve maximum conversion gains of -4 and -6 dB for 12 and 14 dBm input signals, respectively. The fundamental suppression is approximately 30 dBc in both cases. To our knowledge, these results represent the best performance reported to date for W-band balanced doublers.

Large-Signal Oscillator Design Procedure Utilizing Analytical

New analytical behavioral model formulations based on the polyharmonic distortion (PHD) model have been successfully used to describe the nonlinear behavior of transistors and circuits. In this paper, the PHD model and its associated analytical X -parameters formulation will be utilized to provide an analytical design procedure for use in nonlinear microwave circuit design. For RF oscillator design, the negative-resistance method based on the analytical manipulation of scattering parameters is very popular due to its high rate of success in oscillation frequency prediction. However, it cannot be used to accurately predict the oscillator performance because it is based on linear parameters. To overcome this limitation, new analytical expressions based on large-signal X-parameters have been developed for use in transistor-based oscillator circuit design. The robustness of this new approach has been validated by designing and manufacturing a 5-GHz microwave oscillator.

X

Recently, X -parameters have been introduced to model active device nonlinear behavior. In addition to providing a measurement-based tool to numerically predict nonlinear device behavior in computer-aided design, they can also provide the designer of nonlinear circuits an analytical design tool. Exploiting this design tool aspect, this work presents an application that combines the nonlinear vector network analyzer PNA-X and a passive tuner to extract a transistor load-independent X -parameter model, focused around targeted circuit impedances for optimal performance. Furthermore, an experimental search algorithm, based on X-parameters analytical computations and developed by Peláez-Pérez , has been used and experimentally validated in this paper, aimed to speed up the characterization and design process, minimizing the number of load-pull measurements necessary to provide an accurate transistor X-parameter model for use in analytical and/or numerical circuit design.

-Parameters Closed-Form Expressions

In this paper two similar simplified nonquasi-static approaches are applied for high-frequency large-signal FET prediction. Both account for low-frequency dispersion and use a simplified extraction process through the use of linear delays. Excellent results are obtained from dc up to the device f/sub T/ frequencies, even when f/sub T/ is 120 GHz. For low-frequency prediction a simple quasi-static extrinsic approach can produce excellent results thus further simplifying modelling. The influence of including the low-frequency dispersion modelling is also taken into account.

Application of an NVNA-Based System and Load-Independent X-Parameters in Analytical Circuit Design Assisted by an Experimental Search Algorithm

A fully functional table-based nonlinear model of the heterojunction bipolar transistor (HBT) is presented which includes explicit thermal feedback. The model uses four table-based nonlinear functions: I_c, Q_c, V_be, and Q_b, all defined versus I_b and V_ce by using a nonuniform bias grid. Thermal modeling (self-biasing and environment temperature dependence, T_a) is done by linearly mapping the table-based current functions versus T_a coupled with explicit thermal feedback. Four table-based nonlinear coefficients are required to accurately predict the device behavior versus temperature. Excellent results have been obtained under dc, small, and large signal excitations for InGaP/GaAs HBTs in the range 10degC to 110degC.