Nonlinear device characterization using harmonic load pull measurement

There has been a large amount of work and effort in the area of high and medium power MMICs recently. Today nonlinear microwave active devices such as power amplifiers can still benefit from better performance (such as power output and efficiency) by having suitable terminations at various harmonic frequencies. On the other hand, sub-harmonic terminations can affect the stability of the device. The main reason lies in the nonlinear behavior of the device that causes the device to generate various harmonic frequencies apart from the fundamental frequency.;Harmonic Balance (HB) has been a widely used and by far the most popular method to solve for a steady state solution of a nonlinear microwave circuit. It is done by splitting the nonlinear circuit into two parts: a linear part consisting of all the linear circuit elements and a nonlinear part consisting of all the nonlinear parts. Voltages and currents at a number of ports at the interface between the linear and nonlinear part are then computed and matched together using Kirschoff s voltage and current Law; The result is a solution for the voltages and currents and their harmonics at all the ports. In order to use the harmonic balance method, we need some characterization or model of both the linear and nonlinear part. We already have a very good characterization in form of governing equations for the linear part (such as transmission lines, linear resisters, capacitors and inductors). That is not true for the nonlinear active device operating at a large signal level. We still lack a good and sound characterization method for the nonlinear device. This is what we are set to do in this paper. We use a large signal harmonic source/load pull system to present a variety of terminations to the nonlinear device. Measurements of some parameters (such as current, voltage or power variables) of the nonlinear device are performed. We make use of the measured data to come up with a large signal characterization of the nonlinear device that gives the relationship between signals at various frequencies (harmonics) in addition to the frequency of interest

Design of L-S band broadband power amplifier using microstip lines

This contribution introduces a novel broadband power amplifier design, operating in the frequency band ranging from 1.5 GHz to 3 GHz which cover the mainstream applications running in L and S bands. Both matching and biasing networks are synthesized by using microstrip transmission lines. In order to provide a wide bandwidth, two broadband matching techniques are deployed for this purpose, the first technique is an approximate transformation of a previously designed lumped elements matching networks into microstrip matching circuits, and the second technique is a binomial multi-sections quarter wave impedance transformer. The proposed work is based on ATF-13786 active device. The simulation results depict a maximum power gain of 16.40 dB with an excellent input and output matching across 1.5 GHz ~ 3 GHz. At 2.2 GHz, the introduced BPA achieves a saturated output power of 16.26 dBm with a PAE of 21.74%, and a 1-dB compression point of 4.5 dBm input power level. The whole circuitry is unconditionally stable over the overall bandwidth. By considering the broadband matching, the proposed design compares positively with the most recently published BPA

Feed-forward technique to measure the reflection coefficient under CW high-power signals

©2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.This paper describes a measurement setup to obtain the reflection coefficient response over the frequency of a given device when this is subjected to a single-tone high-power (HP) signal. The proposed system is based on a feed-forward technique to cancel the reflected HP signal before reaching the vector network analyzer. This allows measuring the effects of the HP interfering signal into the device's low-power frequency response. This technique does not require either power-calibrated standards or complex calibration techniques. Experiments in several devices are also reported to validate the suitability of this technique.Peer ReviewedPostprint (author's final draft

Novel Approach to Design Ultra Wideband Microwave Amplifiers: Normalized Gain Function Method

In this work, we propose a novel approach called as “Normalized Gain Function (NGF) method” to design low/medium power single stage ultra wide band microwave amplifiers based on linear S parameters of the active device. Normalized Gain Function TNGF is defined as the ratio of T and |S21|^2, desired shape or frequency response of the gain function of the amplifier to be designed and the shape of the transistor forward gain function, respectively. Synthesis of input/output matching networks (IMN/OMN) of the amplifier requires mathematically generated target gain functions to be tracked in two different nonlinear optimization processes. In this manner, NGF not only facilitates a mathematical base to share the amplifier gain function into such two distinct target gain functions, but also allows their precise computation in terms of TNGF=T/|S21|^2 at the very beginning of the design. The particular amplifier presented as the design example operates over 800-5200 MHz to target GSM, UMTS, Wi-Fi and WiMAX applications. An SRFT (Simplified Real Frequency Technique) based design example supported by simulations in MWO (MicroWave Office from AWR Corporation) is given using a 1400mW pHEMT transistor, TGF2021-01 from TriQuint Semiconductor

Design of a Compact GaN Power Amplifier with High Efficiency and Beyond Decade Bandwidth

This letter presents a power amplifier (PA) design and network synthesis approach to achieve wideband and efficient performance with a very compact circuit size. A design method is presented in detail to convert a canonical filter-based high-order matching network to the proposed matching configuration with transistor parasitic and packaged elements absorption, and a compact passive network footprint. As a proof of concept, a prototype GaN HEMT PA is implemented. Starting from a fourth-order output network filter, the inductances and capacitance of the filter elements are re-organized to model, and thus absorb the output parasitics of the transistor, leading to a compact footprint with only four transmission lines. The measured results show that the prototype PA achieves an output power of 41.9-44.3 dBm and a 55-74 % drain efficiency, over a record-high decade bandwidth (0.35-3.55 GHz)

Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature

This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diodedetector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diodedetector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.This work has been funded by the Spanish Ministry for Economy and Competitiveness under the CONSOLIDER-INGENIO 2010 programme under the Reference No. CSD2010-00064. The authors would like to thank Eva Cuerno and Ana Pérez for the assistance in the assembly of the circuit

K-Band GaAs MMIC Doherty Power Amplifier for Microwave Radio With Optimized Driver

In this paper, a Doherty power amplifier for K-band point-to-point microwave radio, developed in TriQuint GaAs um PWR pHEMT monolithic technology, is presented. Highly efficient driver stages on both the main and auxiliary branches have been designed and optimized to boost gain with minimal impact on power-added efficiency. The selected architecture enables a modular combination to reach higher power levels. Matching network structures have been designed, according to simple equivalent circuit approaches, to obtain the desired 10% fractional bandwidth. The fabricated power amplifier (PA) exhibits, at 24 GHz in continuous-wave conditions, an output power of 30.9 dBm, with a power-added efficiency of 38% at saturation and 20% at 6 dB of output power back-off, together with a gain of 12.5 dB. System-level characterization at 24 GHz, in very demanding conditions, with a 28-MHz channel 7.5-dB peak-to-average ratio modulated signal, showed full compliance with the standard emission mask, adopting a simple predistorter, with average output power of 23.5 dBm, and average efficiency above 14%. The measured performance favorably compare with other academic and commercial K-band PAs for similar applications

Nonlinear simulation and characterization of devices with HTS transmission lines using harmonic balance algorithm

This work presents the use of Harmonic Balance to simulate the nonlinear behavior of HTS transmission lines. Good agreement with theoretical cross-checks is found. We also show the use of this algorithm to fit the model of HTS lines from experimental measurements. We illustrate this by fitting several types of experimental data, and discuss how to avoid ambiguity in this fittingPeer ReviewedPostprint (published version