Search

This paper presents a comprehensive study on the effective utilization of large-signal measurement data in the nonlinear computer-aided design (CAD) process. To achieve this goal two distinctive, yet mutually complementary, approaches have been integrated. Measured nonlinear data was, in the first instance, directly integrated into a nonlinear CAD simulator, and in the second instance, utilized for a direct extraction of behavioral model parameters. The formulation of the developed model is based on the polyharmonic distortion approach. The combination of both the direct utilization of nonlinear data and the subsequent model generation into an integrated nonlinear design procedure offers rapid, yet reliable, deployment of the CAD-based design environment for complex large-signal simulations. Index Terms--Design automation, measurement system data handling, microwave measurements, nonlinear systems, power amplifiers.

A study is conducted to gain insight into dc-radio-frequency (dc-RF) dispersion problems in GaN heterojunction field-effect transistors (HFETs) through RF waveform measurements performed across a range of RF load impedances and physical device modeling. The differences in dispersive behaviors are attributed to the geometry of a trap-induced virtual-gate region and the resulting carrier velocity saturation overcome by punchthrough effects under high electric fields.

The differential gain of GaAs-based multiple quantum well lasers (MQW), at a specific drive current, results in modulation bandwidth improvement and an increase in the addition of QW's, and strained QW's elevates the differential gain. The damping factor K decreased while the differential gain increased under conditions of p-doping in the quantum wells. Intraband relaxation time decreased causing a nonlinear gain coefficient reduction which contributed to the improvements in p-dope laser performance.

An accurate database for active and passive MMIC components valid up to millimeter-wave frequencies has been established. The CAE models for the transistors and the passive CPW-components, which include the coplanar T-junction, are derived from on-wafer S-parameter measurements up to 63 GHz. For noise modeling of the MODFETs up to millimeter-wave frequencies, we have pursued a novel approach which is based on the temperature noise model reported by Pospiezalski (1). The parameter T(sub d) which is required for the temperature model, is extracted from on-wafer noise parameter measurements up to 18 Ghz. Using this database, we have designed and fabricated low noise V-band 2-stage amplifiers using pseudomorphic MODFETs on GaAs substrate which have a performance of 10.5 dB gain and 5.2 dB noise figure at 58.5 GHz. A very good agreement between simulated and measured MMIC gain and noise performance is achieved up to V-band.

A measurement system combining vector corrected waveform measurements with active harmonic load--pull extends, for the first time, real-time experimental waveform engineering up to the 30-W power level. The vector correction procedure is presented in this paper. A novel harmonic load-pull approach based on the real-time measurement capability of the system is demonstrated on a 4-W LDMOS device. A 20% increase in maximum output power to 4.7 W without degrading gain and efficiency is realized. Waveform analysis at various drive and load conditions directly identifies nonlinear capacitance effects being a key design issue for the design of highly efficient power amplifier. Index Terms--Active load-pull, calibration, microwave measurements, microwave power amplifier, modeling, MOSFETs, nonlinearities, time-domain measurements.

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 y-parameters at high frequencies is taken into account through the use of linear delays. This model is suitable for applications related with 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. Index Terms--FET's, modeling.