Part 1 of this FAQ was a basic introduction to the context and concept of s-parameters. Part 2 looks at their measurement and application and relationship to the time domain. Q: How do you actually measure s-parameters? A: In general, except for approximate measurements, you cannot use a spectrum analyzer alone for this frequency-domain test. […]
What are the functions and principles of S-parameters (Part 1)?
As design frequencies now routinely go into the hundreds of MHz and tens of GHz range, conventional voltage and current measurements are not useful, but scattering (s) parameters can fully characterize the RF component or path performance. For engineers with experience focused from DC to several hundred megahertz, it is usually sufficient to characterize components […]
RF Switches, Part 2: Analog and MEMS switches
Part 1 of this FAQ looked at the venerable electromechanical RF switch – still widely used in some applications, where it is the only viable option – and use of PIN diodes as RF switches. This part looks at analog and MEMS-based switches. Q: What is an analog switch? A: It’s conceptually straightforward: in basic […]
RF switches, Part 1: Mechanical and PIN-diode switches
There’s a ubiquitous and increasing need to switch RF signals ranging into the tens of GHz; four basic switch technologies – electromechanical, PIN diode, analog, and MEMS – are available, each with different features and capabilities. The need to switch RF signals has been a necessary design function since the earliest days of “wireless.” This […]
RF/microwave noise, Part 1: Noise figure basics
The lower-frequency world of electronic circuits and systems for communications links routinely uses parameters such as voltage and current, bit rates, and signal/noise ratio, to cite just a few of many, many possibilities. While these are also important in the world of RF and microwave links and system functions, engineers doing work in this arena […]
Load pull for RF devices, Part 2: How and where
Part 1 of this FAQ explained the what and why of load-pull tests of RF devices and impedance matching. Part 2 looks at various ways the test can be set up and run. Q: What’s the basic test setup for a modern load pull? A: As shown in the figure of Part 1 (and repeated […]
Load pull for RF devices, Part 1: What and why
Impedance matching between RF stages has always been a priority to ensure maximum transfer of RF power along with minimal RF-power reflections. Although most RF systems are designed for nominal 50-ohm input and output impedance (and 75-ohm for cable TV), the reality is that many components do not present that preferred 50-ohm impedance due to […]
RF power measurement, Part 2: What and how
Part 1 of this FAQ introduced some of the basic issues related to the measurement of RF power, which is a primary parameter in most RF designs. Part 2 continues the discussion, looking at RF waveforms and sensors. Q: The term “power” is fairly broad; what are the specifics? A: There are actually several basic […]
RF power measurement, Part 1: Why and where
When the subject is RF design, the word “power” dominates much of the discussion. This FAQ looks at some perspectives related to the measurement of this vital RF parameter. Not only is power and measuring it among the most important RF design considerations, but it is also generally difficult to assess accurately, and it is […]
The RF power amplifier, Part 2: Considerations
Part 1 of this FAQ looked at the basic role and function of the RF power amplifier (PA). This part looks at some of the factors to consider when looking at possible PA devices. It is not a detailed run-through of the many parameters which characterize PAs, including many which are unique to the PA […]
