Ewout Vandamme

Development of a RF large signal MOSFET model, based on an equivalent circuit, and comparison with the BSIM3v3 compact model.

The improved RF performance of silicon-based technologies over the years and their potential use in telecommunication applications has increased the research in RF modelling of MOS transistors. Especially for analog circuits, accurate RF small signal and large signal transistor models are required. In this paper, we propose an accurate, non-quasi-static, large signal (i.e., nonlinear) RF MOSFET model. Our model consists of a current source and a charge source at the drain terminal and a charge source at the gate terminal. The sources magnitudes are calculated from the gate-bias and drain-bias dependent elements of the MOSFET equivalent circuit. The MOSFET equivalent circuit elements on itself are extracted from S-parameters at all gate voltages and drain voltages that occur in large signal operation. The accuracy of the equivalent circuit based model is validated by large signal RF measurements using a nonlinear network measurement system. Large signal modelling results using the BSIM3v3 compact model are also presented. Both the equivalent circuit based model and the BSIM3v3 model meet the requirements to describe accurately the RF large signal behaviour of MOS transistors.

Calibration issues for the large signal network analyzer (LSNA)

There is a growing need for measuring the large signal (nonlinear) behavior of devices in their nonlinear regions under excitation of complex modulated signal schemes, as commonly used in telecom applications. The large-signal network analyzer (LSNA) based on J. Verspecht et al. (2002) developed by Agilent Technologies-NMDG is able to measure incident and scattered traveling voltage waves (or voltages and currents) appearing at both signal ports (input and output) of a DUT under periodical excitations or periodically modulated excitations. Since phase relations between the fundamental and higher harmonics are included in the measured signals, the complete behavior of the DUT is measured and accurate models to predict the DUT-behavior can now be extracted out of the measured data based on J. Verspecht and D. Schreurs (1999). In this paper, some solutions to carry out the LSNA calibration for broadband modulated multitone signals and some observations aiming at high-power applications related to the controllable step-attenuators in the measurement channels are discussed.

Large-Signal Network Analysis. Overview of the measurement capabilities of a Large-Signal Network Analyzer

This article explains the rationale of performing ¿large-signal network analysis¿ and the basic concepts involved. The focus is on the measurement technology required to perform fully calibrated measurements on nonlinear devices in a versatile environment (different bias, source and load mismatch conditions, continuous wave or modulation). Furthermore this technology is compared to existing approaches. Finally a readily available measurement system is described, which represents the latest developments from Agilent Technologies in the domain of large-signal network analysis.

Capabilities of Vectorial Large-Signal Measurements to Validate RF Large-Signal Device Models

The trend towards system-on-chip realisation tightens the design specifications and consequently imposes high accuracy requirements on device models. This paper presents an overview of the surplus value of using vectorial large-signal measurements to validate the large-signal accuracy of RF MOSFET models. We show that these models can be evaluated at operating conditions close to real applications, such as intermodulation characterisation combined with loadpull. The large-signal model verification is not limited to analogue applications, because also the RF large-signal performance of digital circuits, such as inverters, can be examined. In this paper, we focus to the results obtained for the BSIM3v3 compact model and for the in-house developed large-signal look-up table model.

5.5GHz LSNA MOSFET modeling for RF CMOS circuit design

The recent trend towards integrating an entire transceiver, with all its RF/analog/DSP functions, on a single CMOS chip is a consequence of strong market demands on RF chip size, cost, reliability, battery-life, etc. The design of a modern RF CMOS chips generates various technical challenges due to circuit complexity, signal complexity, and integration issues. Advanced LSNA characterization and modeling of deep submicron devices are critical to modern RF CMOS circuit design. This paper reviews some of the RF device level modeling technologies required for the design of RFICs. The LSNA modeling is performed using Agilents characterization, parameter extraction and simulation tools flow.

Use of Vectorial Large-Signal Measurements to Experimentally Evaluate Digital Circuits at Microwave Frequencies: Application to Inverters

In this work, we characterise for the first time a digital circuit, and more specifically an inverter, by means of vectorial large-signal measurements. The results give us a more complete picture of its behaviour at microwave frequencies, since parameters such as charging and discharging currents, peak currents, influence of the applied load, . . ., can now be visualised and evaluated directly. Moreover, device models aimed for digital circuit design can now be verified in detail under realistic digital operating conditions, whereas the classical validation by means of standard ring oscillator measurements only provides global information, such as delay and power dissipation. Finally, we also outline the importance of well incorporating the measurement environment (probe pads, biasing networks, . . .) when analysing measurement data of inverters at microwave frequencies.