Understanding Additive Phase Noise in RF & Microwave Amplifiers – Part 3
In the 3rd and final part of our series on amplifier additive phase noise testing at Mini-Circuits, we continue our investigation into cascaded amplifiers. Part 2 considered two identical amplifiers in series and four identical amplifiers in parallel. However, we were unable to clearly demonstrate the improvement in 1/f noise provided by the parallel configuration due to equipment noise floor limitations.
In Part 3 we address this limitation by driving the four parallel amplifiers with a single amplifier, all identical, and demonstrate that the cascaded performance is dominated by the single driver amplifier.
We also describe how to best optimize the input power levels into each amplifier in order to avoid regions of high AM-to-PM distortion and achieve optimum performance over a wide bandwidth.
About Mini-Circuits:
Mini-Circuits is the world’s preferred supplier of RF and microwave components and systems. With 14 design, manufacturing and sales locations in nine countries, as well as hundreds of sales channel partners worldwide, Mini-Circuits offers 27 product lines comprising over 10,000 active models. Over 20,000 customers choose Mini-Circuits for the demanding quality standards, world-class customer support, on-time delivery and value pricing that have earned the industry’s trust for over 50 years.
Understanding Additive Phase Noise in RF & Microwave Amplifiers – Part 2
In this second video in our series on RF amplifier additive phase noise, Mini-Circuits VP of engineering, Joe Merenda takes a deeper dive into cascaded amplifiers in LO chains. The discussion explores how to configure lineups of 2 amplifiers in series, and 4 amplifiers in parallel to achieve optimum additive phase noise performance. Testing phase noise in cascade vs. parallel setups, observing noise performance across amplifiers, and characterizing behavior in high-frequency environments are discussed in turn.
About Mini-Circuits:
Mini-Circuits is the world’s preferred supplier of RF and microwave components and systems. With 14 design, manufacturing and sales locations in nine countries, as well as hundreds of sales channel partners worldwide, Mini-Circuits offers 27 product lines comprising over 10,000 active models. Over 20,000 customers choose Mini-Circuits for the demanding quality standards, world-class customer support, on-time delivery and value pricing that have earned the industry’s trust for over 50 years.
Understanding Additive Phase Noise in RF & Microwave Amplifiers – Part 1
The webinar “Understanding Additive Phase Noise in RF & Microwave Amplifiers – Part 1” features Joe Merenda, Vice President of Engineering at Mini-Circuits, presenting an in-depth overview of additive phase noise (APN) in RF and microwave amplifier systems. Additive phase noise refers to the additional phase noise that an amplifier introduces to an already modulated input signal. This concept is especially important in high-frequency applications such as radar, satellite communication, and wireless systems where phase purity directly affects system performance.
Phase-Matched Cable Assemblies
Phase-matched cable assemblies are ubiquitous, and modern-day phase matching requirements serve to drive their growing popularity. As electrical length matching requirements have tightened to less than one or two degrees, the mechanical precision with which various styles of cable are constructed has improved to keep pace. Additionally, dielectrics more exotic than tried-and-true Teflon are being researched and introduced to afford greater phase stability. Volumes have been written on how to phase-match cable assemblies and dozens and dozens of companies practice this discipline. Why is phase-matching so prevalent, and why does it matter so much? In this article we answer these questions by highlighting many phase-matched cable applications and the effect of varying phase length on systems in the RF/microwave domain. We also describe Mini-Circuits’ capabilities in the phase-matching cable arena.
A Primer on Quadrature Amplitude Modulation (QAM)
While other modulation schemes discussed in this blog series (pulse, frequency, amplitude, phase) date back to the early chapters of RF engineering history, quadrature amplitude modulation (QAM) was first described by C. R. Cahn in 19602 and evolved steadily over the next few decades. In the last 25 to 30 years, no modulation scheme has seen such widespread development and application as QAM. The technology has played a pivotal role in the industry’s ability to scale data speed and capacity with user demand by packing more data onto the carrier waveform and pushing a fixed channel bandwidth closer to Shannon’s limit. QAM modulation is used widely in cellular networks and backhaul, CATV networks and fixed wireless access points (802.11), and satellite communications to name a few. See Table 3 in Reference [3] for a more detailed list of applications.
In this article, we describe QAM using basic mathematics and illustrate how a QAM modulator operates. We introduce the concept of a constellation diagram and how it relates to the time domain plots for QAM modulation. A representative set of components is then utilized to design a functional QAM modulator by way of illustration. We conclude by describing how the QAM signal is demodulated at the receiver.
Fully Non-Blocking (Full Fan-Out) RF Switch Matrices
The first two articles in this series established that blocking switch matrices use switches to allow one-to-one connections between input and output ports, while non-blocking switch matrices use splitter/combiners on either the input our output ports to allow one-to-many or many-to-one connections. In this article, we’ll examine the fully non-blocking or “full fan-out” configuration in which all inputs are connected simultaneously to all outputs via splitter/combiners, sometimes with programmable attenuation on every path. Features, advantages, applications and examples will be reviewed.
Switch Matrix Configurations
Switch matrices are an essential tool for control of RF signal routing in any environment where there is a recurring need to change how systems interconnect. The addition of Ethernet and USB interfaces with flexible software and APIs (application programming interfaces) makes switch matrices particularly useful in automated test environments, allowing test sequences to be scheduled to run with no user intervention, switching between multiple devices under test (DUT), input / output ports and test equipment.
RF Blocking Switch Matrices
Blocking switch matrices are constructed using switches on the inputs and outputs, as shown in Figure 1. They are called “blocking” because once a path is set between any pair of ports, those 2 ports are not available (blocked) for use by any other path. Multiple paths can be active in parallel, up to the number of input ports or the number of output ports (whichever is fewer), with each path connecting a different pair of ports.
RF Non-Blocking Switch Matrices
Non-blocking switch matrices are constructed using switches on one set of ports and passive splitter / combiners on the other. They are referred to as non-blocking (sometimes partially non-blocking) since the splitter / combiner component allows a single port to be connected concurrently to multiple ports on the opposite side. Hence the path is not blocking any other ports from connecting, as would be the case with a blocking switch matrix.
Non-blocking matrices are often characterized as either fan-in or fan-out depending on the orientation of the splitter / combiners relative to the input ports.
BOOST YOUR KNOWLEDGE: A COMPREHENSIVE GUIDE TO RF BIAS TEES – TYPES AND APPLICATIONS EXPLAINED
RF Bias Tees are electronic devices that are used to combine DC power and RF signals on a single transmission line. These devices are used in a wide range of applications, including wireless communication systems, test and measurement equipment, and RF circuit design. RF bias tees can also be used to power active RF components, such as amplifiers and mixers, while also allowing the RF signal to pass through the device.
