This paper addresses the challenges of working with semiconductor memory-effects when designing high-frequency power amplifiers. The paper presents a discussion of what memory-effects are, how they impact amplifier performance, and how to characterize memory-effects using X-parameters in order to achieve optimum amplifier performance.
In RF systems, switches are as common as amplifiers, mixers, and PLLs. While many technologies yield good active RF devices, few yield good RF switches. Superior switches are available in Peregrine’s UltraCMOS™ process technology.
You can’t build a house without blueprints. So why do so many RF design flows try to build a board without a schematic? Often, this crude process came about due to lack of availability of RF design tools. But the wireless industry is the new cool kid on the block. As a result, EDA software vendors are scrambling to disencumber the rigid PCB world of tailored processes and streamlined user flows. RF engineers demand freedom from constraints, so EDA vendors are peeling back the layers of traditional PCB design and opening some excellent solutions. But with these solutions, RF engineers are challenged to rethink their request for primitive simplicity and consider a higher level process.
Conventional analog RF transceiver implementations have many performance limitations that include RF frequency dependency, non-linearities, high insertion losses, circuit tuning requirements and expensive inter-connections that ultimately bound the performance of the complete earth terminal. These limitations are greatly multiplied when operational scenarios call for multiple frequency bands, multiple beams and multiple channel configurations. These analog RF channel designs are highly frequency dependent and not optimized for an OSA. As a result, multi-band SATCOM terminals are often found to be complex and costly. An all-digital RF implementation can potentially solve these problems as it can provide a highly linear digital RF signal distribution system and can provide multiple band, frequency and channel operation within a single integrated product.
VNAs have been the workhorse of microwave measurements for many years. They provide the ability to measure S parameters of active and passive devices and systems. When measuring active devices, these measurements are made on small signal devices where gain is linear. When measuring small signal amplifiers, the linear VectorStar VNA provides many built-in functions to thoroughly analyze these active devices. Applications such as built-in programmable power sweeps for gain compression analysis at multiple frequency points, IMD measurements, harmonic measurements, characterization down to 70 kHz to evaluate memory effects, etc., are all available in the VectorStar VNA. Table 1 provides a brief overview of the capabilities of the MS4640A family of VectorStar VNAs.
This application note from Agilent is part of a series on using measured-based nonlinear behavorial models in high frequency simulations. This paper looks at characterizing multi-stage circuits such as a cascaded ampilifer using measured data based on arbitrary load impedance X-parameters.
This application note discusses the unique challenges involved in testing high power devices using Agilent's nonlinear vector network analyzer (NVNA). In this application note, the term “high power” refers to those cases in which the power levels of the device under test (DUT) exceed the maximum levels of the network analyzer.
This application note will highlight some of the major RF amplifier characteristics that impact forward power as well as net power allowing the use of Ohm’s law, even when conditions are far from ideal.
This white paper presents examples illustrating how VSS/TestWave software from AWR enables engineers to design communications systems with the highest possible performance by integrating the once distinct domains of simulation and measurement.