Preface. Introduction, Fundamental Concepts, and Definitions. Solid-State Device Modeling. Harmonic-Balance analysis. Volterra-Series and Power-Series Analysis. Balanced Circuits. Diode Mixers. Diode Frequency Multipliers. Small-Signal Amplifiers. Power Amplifiers. Active Frequency Multipliers. Active Mixers. Oscillators. Index.

Nonlinear Microwave and RF Circuits

Introduction Some Circuit Theory and Terminology Memory Effects in RF Power Amplifiers The Volterra Model Simulating and Measuring Memory Effects Cancellation of Memory Effects Characterization of the Volterra Model Appendix A: Volterra Analysis in More Detail Appendix B: IM3 Equations for Cascaded 2nd-Order Distortion Mechanisms Appendix C: The Truncation Error

Distortion in RF power amplifiers

An accurate characterization of the nonlinear distortion caused by the Ids(Vgs,Vds) current in a MESFET, does not allow the common approach of splitting this nonlinear equivalent circuit element in two voltage dependent nonlinear current sources, Gm(Vgs) and Gds(Vds). By an improved laboratory characterization procedure, it was possible to extract the cross terms of the Ids(Vgs,Vds) Taylor series expansion. Measurements and Volterra series simulations, made at 2 GHz, have shown that they can give an important contribution to the prediction and understanding of MESFET's intermodulation load-pull behavior. >

Accurate simulation of GaAs MESFET's intermodulation distortion using a new drain-source current model

We present the development of a device-level linearization technique and its applications in broadband power amplifiers (PAs). The proposed topology firstly combines derivative transconductance superposition method and gate capacitance compensation technique, and creates a "sweet region" for suppressing third-order intermodulation (IM3) without the penalty of large power consumption. The effectiveness of the proposed technique has been demonstrated through a fully integrated distributed amplifier. The experimental results in 0.18-mum RF CMOS technology show that IM3 is improved by 11 dB. The achievable power-added efficiency is up to 25%, which is the highest among the broadband CMOS PAs reported thus far. The amplifier achieves a measured 3-dB bandwidth of 3.7-8.8 GHz, and a gain of 8.24 dB. The amplifier only consumes 154-mW dc power, and the measured saturation power (Psat) is 19 dBm.

Linearization of CMOS Broadband Power Amplifiers Through Combined Multigated Transistors and Capacitance Compensation

The authors show that the Taylor-series coefficients of a FET's gate/drain I/V characteristic, which is used to model this nonlinearity for Volterra-series analysis, can be derived from low-frequency RF measurements of harmonic output levels. The method circumvents many of the problems encountered in using DC measurements to characterize this nonlinearity. This method was used to determine the incremental gate I/V characteristic of a packaged Aventek AT10650-5 MESFET biased at a drain voltage of 3 V and drain current of 20 mA. The FET's transconductance was measured at DC, and its small-signal equivalent circuit (including the package parasitics) was determined by adjusting its circuit element values until good agreement between calculated and measured S parameters was obtained. The FET was then installed in a low-frequency test fixture. Excellent results were obtained. >

Modeling the gate I/V characteristic of a GaAs MESFET for Volterra-series analysis

It is shown how the intermodulation (IM) distortion performance of a small-signal amplifier can be optimized when the amplifier is designed according to available-gain criteria. In this process the MESFET's output is conjugate-matched and its input is mismatched to obtain a specified gain. This method generally results in a better dynamic range than obtained with other options such as matching the input and mismatching the output or simultaneously matching both the input and output (which, in many cases, is impossible). In available-gain design the value of source impedance that provides the desired gain is not unique and can be selected to optimize IM levels. A numerical formulation of the Volterra series allows a complete equivalent circuit of the FET to be used, and the intermodulation calculations include all feedback effects. The sensitivity of the IM intercept point (IP/sub 3/) to the source-reflection coefficient, Gamma /sub s/, is shown to decrease with increasing frequency and is related to the MESFET's stability. >

A.M. Crosmun

Papers

Minimization of intermodulation distortion in GaAs MESFET small-signal amplifiers