Passive intermodulation (PIM) is a pernicious and destructive phenomenon for cellular network operators. PIM shows up as a set of unwanted signals created by mixing two or more strong RF signals. Mixing generally produces the sum and difference frequencies of the two transmit signals F1 and F2. These signals are F1 + F2 and F1 […]
FAQ
Audio filters: Understanding acoustic waves – Part 2
In the previous tutorial, sound waves and their properties were discussed. Now, let’s learn about acoustic waves. Sound waves typically refer to frequencies that are audible to humans, which are in the 20 Hz to 20 kHz range. However, waves with frequencies that are greater than 20 kHz are ultrasonic waves. And, those in the […]
Audio filters: Understanding sound waves – Part 1
Audio electronics is a sector that refers to the circuit design that converts sound into electrical signals or electrical signals back into sound. Together, several circuits form an audio system. An audio system has several functions and, typically, can: Receive audio signals (via a microphone) Record and save audio Transmit audio (through wired or wireless […]
VSWR and impedance, Part 6: Microstrip and stripline
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The traditional matching approaches are still in wide use, but new application requirements and advances in components, modeling and simulation, and manufacturing precision have also provided new ways to address the matching problem. Q: What is […]
VSWR and impedance, Part 5: Making a match
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The importance of impedance matching, minimizing reflections, and keeping a low VSWR means these topics have been studied extensively, ranging from analytical perspectives through many physical designs and implementations. This section looks at some matching techniques. […]
Negotiate through 1/f noise challenges towards sample sizes into the 100s of years
Measuring and determining 1/f voltage noise over a multiple-year sample requires an operational amplifier and effective 1/f knowledge. This article shows how to identify and determine the actual op amp 1/f voltage noise across a sample size of years and explains why the 1/f voltage noise is a non-issue at higher frequencies. After many years […]
VSWR and impedance, Part 4: Measurements
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The previous section looked at the basics of VSWR. This section looks at two approaches to measuring impedance and VSWR. Q: What do engineers and users need to know? A: For some applications, such as connecting […]
VSWR and impedance, Part 3: Implications
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. The previous sections looked at the basics of impedance and VSWR. This section looks at the implications of VSWR measurements. Q: Why should I care about reflected waves due to impedance mismatch and resultant non-unity VSWR? […]
VSWR and impedance, Part 2: Reflected power
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. Part 1 of this article looked at the basics of impedance matching and power transfer. This part looks at the closely related topic of nominal impedance and VSWR. Q: Why all this worry? Aren’t RF systems […]
The basics of VSWR and impedance, Part 1
Understanding the role and implications of impedance in RF transmission lines and antennas is vital to successful system performance. In any design requiring transfer of an RF signal and its energy from one functional block or component in a system to a subsequent one in the signal chain, there’s almost always the issue of impedance […]
