This paper presents a theoretical analysis of harmonically terminated high-efficiency power rectifiers and experimental validation on a class-C single Schottky-diode rectifier and a class- F-1 GaN transistor rectifier. The theory is based on a Fourier analysis of current and voltage waveforms, which arise across the rectifying element when different harmonic terminations are presented at its terminals. An analogy to harmonically terminated power amplifier (PA) theory is discussed. From the analysis, one can obtain an optimal value for the dc load given the RF circuit design. An upper limit on rectifier efficiency is derived for each case as a function of the device on-resistance. Measured results from fundamental frequency source-pull measurement of a Schottky diode rectifier with short-circuit terminations at the second and third harmonics are presented. A maximal device rectification efficiency of 72.8% at 2.45 GHz matches the theoretical prediction. A 2.14-GHz GaN HEMT rectifier is designed based on a class-F-1 PA. The gate of the transistor is terminated in an optimal impedance for self-synchronous rectification. Measurements of conversion efficiency and output dc voltage for varying gate RF impedance, dc load, and gate bias are shown with varying input RF power at the drain. The rectifier demonstrates an efficiency of 85% for a 10-W input RF power at the transistor drain with a dc voltage of 30 V across a 98-Ω resistor.

/pdf/high-efficiency-harmonically-terminated-diode-and-transistor-4h4adt3l79.pdf

High-Efficiency Harmonically Terminated Diode and Transistor Rectifiers

This paper, for the first time, analyzes in detail the kink phenomenon in S22 as observed in GaN HEMT technology. To gain a comprehensive understanding, the kink effect (KE) is studied with respect to temperature and bias conditions. The achieved results clearly show that the dependence of the KE on the operating condition should be mainly ascribed to the transconductance, which plays a determinant role in the appearance of this effect. Furthermore, the analysis is extended to investigate the peak in the magnitude of h21 showing its disappearance at low drain-source voltage, due to the increase of the intrinsic output conductance. The importance of this investigation originates from the fact that an accurate and complete characterization of these anomalous phenomena enables microwave engineers to properly take them into account during the modeling and design phases.enables microwave engineers to properly take them into account during the modeling and design phases.

An Extensive Experimental Analysis of the Kink Effects in ${ S}_{22}$ and ${ h}_{21}$ for a GaN HEMT

Frequency dispersion of transconductance and output conductance in AlInN/GaN high electron mobility transistors is investigated in this paper. Broadband dispersion effects in the microwave frequency range are reported for the first time. A small-signal model is developed. Trapping effects are taken into account with parasitic electrical networks including distributed time constants. The model is compared with experimental data for several bias conditions and different types of dispersion.

/pdf/broadband-frequency-dispersion-small-signal-modeling-of-the-511thqxhhj.pdf

Broadband Frequency Dispersion Small-Signal Modeling of the Output Conductance and Transconductance in AlInN/GaN HEMTs

The similarity between RF power amplifiers and rectifiers is discussed. It is shown that the same high-efficiency harmonically-terminated power amplifier can be operated in a dual rectifier mode. Nonlinear simulations with a GaN HEMT transistor model show the time-reversal intrinsic voltage and current waveform relationship between a class-F amplifier and rectifier. Measurements on a class-F-1 amplifier and rectifier at 2.14 GHz demonstrate over 80% efficiency in both cases.

/pdf/time-reversal-duality-of-high-efficiency-rf-power-amplifiers-1ycinet5py.pdf

Time-reversal duality of high-efficiency RF power amplifiers

We propose here a non-linear GaN HEMT model for CAD including a trapping effects description consistent with both small-signal and large-signal operating modes. It takes into account the dynamics of the traps and then allows to accurately model the modulated large signal characteristics that are encountered in telecommunication and radar signals. This model is elaborated through low-frequency S-parameter measurements complementary to more classical pulsed-IV characterizations. A 8×75μm AlInN/GaN HEMT model was designed and particularly validated in large-signal pulsed RF operation. It is also shown that thermal and trapping effects have opposite effects on the output conductance, thus opening the way for separate characterizations of the two effects.

/pdf/modeling-of-trap-induced-dispersion-of-large-signal-dynamic-51d1m5frbv.pdf

Modeling of trap induced dispersion of large signal dynamic Characteristics of GaN HEMTs

This paper presents a set-up which enables the generation and the calibrated time domain measurements of complex envelopes of modulated signals at both ports of non linear microwave power amplifiers. The architecture of the characterization tool is given. Examples of error corrected time domain envelopes at the input / output RF ports of a 36 dBm output power – 30dB power gain L-band SSPA are shown. Futhermore, the use of this characterization tool and a suitable processing of measurement data are applied to a novel measurement based behavioral modeling approach of non linear devices accounting for memory effects.

/pdf/a-calibrated-time-domain-envelope-measurement-system-for-the-3l7mhl671y.pdf

A Calibrated Time Domain Envelope Measurement System for the Behavioral Modeling of Power Amplifiers

We present here a new set of equations for modeling the I–V characteristics of Field Effects Transistors (FETs), particularly optimized for AlGaN/GaN HEMTs. These equations describe the whole characteristics from negative to positive breakdown loci, and reproduce the current saturation at high level. Using this model enables to decrease the modeling process duration when a same transistor topology is used for several applications in a T/R module. It can even be used for switches design, which is the most demanding application in terms of I–V swing. Moreover, particular care was taken to accurately model the first third orders of the current derivatives, which is important for multione applications. We also focused on an accurate definition of the nonlinear elements such as capacitances for power applications. There are 18 parameters for the main current source (and six for both diodes Igs and Igd). This can be compared to Tajima's equations-based model (13 parameters) or to the Angelov model (14 parameters), which only fit the I–V characteristics for positive values of Vds. We will detail here the model formulation, and show some measurements/modeling comparisons on both I–V, [S]-parameters and temporal load-pull obtained for a 8 × 75 μm GaN HEMT, with 0.25 μm gate length.

A new nonlinear HEMT model for AlGaN/GaN switch applications

A test bench allowing S-parameters measurements from 10 Hz to 40 GHz has been set-up, this set-up has been used to investigate the DC to RF behavior of AlInN/GaN HEMTS. The measurement performed have demonstrated the dispersion effects observed on GaN HEMTS due to trapping effects and proved very useful for in-depth characterization of RF devices.

http://ieeexplore.ieee.org/iel5/6089237/6102757/06102856.pdf

DC (10 Hz) to RF (40 GHz) output conduction extraction by S-parameters measurements for in-depth characterization of AlInN/GaN HEMTS, focusing on low frequency dispersion effects

This paper presents an extension of a three step de-embedding (Pad-Open-Short) method to a 3-port device for accurate on wafer MMIC S-parameters measurements. In the proposed method, an equivalent circuit-model using lumped elements is established according to the test-fixture. Furthermore, classical Pad-Open-Short method introduces systematic errors, observed beyond 20 GHz, due to perfect ‘Open’ and ‘Short’ standards assumption. This work also proposes a generalized Pad-Open-Short method with non-ideal standards. To validate the performance of this new method, reliable data were obtained from simulations and measurements of a GaAs transistor from UMS foundry operating up to 40 GHz.

Raymond Quéré

Papers

A Calibrated Time Domain Envelope Measurement System for the Behavioral Modeling of Power Amplifiers

A new nonlinear HEMT model for AlGaN/GaN switch applications

DC (10 Hz) to RF (40 GHz) output conduction extraction by S-parameters measurements for in-depth characterization of AlInN/GaN HEMTS, focusing on low frequency dispersion effects

Pad-open-short de-embedding method extended for 3-port devices and non-ideal standards

High Power S Band Limiter Simulation with a.