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Understanding Noise in FM Systems: The Tone-Modulated Scenario, Part 2

Understanding Noise in FM Systems: The Tone-Modulated Scenario, Part 2

This article explores how combining signal and noise power reveals how the FM system’s output SNR scales with carrier amplitude and modulation index.


A Dual 38W Power Amplifier: A Compact STA540-Based Stereo Audio Board

A Dual 38W Power Amplifier: A Compact STA540-Based Stereo Audio Board

This project brief describes how to build a compact dual-channel power amplifier module that delivers 38 W per channel into 4-ohm speakers using STMicroelectronics' STA540 audio amplifier IC.


Understanding Noise in FM Systems: The Tone-Modulated Scenario, Part 1

Understanding Noise in FM Systems: The Tone-Modulated Scenario, Part 1

Explore how frequency-modulated waves resist interference. We break down the demodulator architecture and derive the exact output signal power for a sinusoidal message.


Understanding the Noise Performance of AM Receivers with Envelope Detection

Understanding the Noise Performance of AM Receivers with Envelope Detection

Envelope detection is simple, but that simplicity has a noise-performance cost. Here’s how much SNR conventional AM gives up compared to its coherent counterparts.


An Ultra-Low-Noise Pre-Amp For Audio Applications

An Ultra-Low-Noise Pre-Amp For Audio Applications

Build an ultra-low-noise preamplifier with a JFE150 JFET and OPA202 op-amp, perfect for high-impedance sensors, hydrophones, guitar pickups, microphones, and turntables.


Analyzing the Noise Performance of Coherent SSB Demodulators

Analyzing the Noise Performance of Coherent SSB Demodulators

Using a graphical approach, we show that coherent SSB demodulation leaves the input and output SNR unchanged, then compare its noise performance to DSB-SC and baseband systems.


Understanding SNR in DSB‑SC Coherent Detection: A Graphical Approach

Understanding SNR in DSB‑SC Coherent Detection: A Graphical Approach

Visualizing how correlated and uncorrelated signals combine offers an intuitive look at power transformation. See how this difference boosts baseband power to double the output SNR.


Designing a Tuneable Ultrasonic Filter

Designing a Tuneable Ultrasonic Filter

Learn how to build a constant-bandwidth band-pass filter covering 20 kHz to 60 kHz, with an integrated frequency counter for precise tuning.


Evaluating the Noise Performance of Coherent DSB‑SC Demodulators

Evaluating the Noise Performance of Coherent DSB‑SC Demodulators

In this article, we'll learn how to calculate the noise power and signal-to-noise ratio (SNR) of a double-sideband suppressed-carrier communication system.


The Voice Echo: An Arduino Audio Project

The Voice Echo: An Arduino Audio Project

This project brief explains how to construct a PCB-based audio-processing platform with an ATmega328 microcontroller. A link to Arduino code for creating an audio echo is also provided.


From Tracking Filters to Demodulation: Exploring the Applications of PLLs

From Tracking Filters to Demodulation: Exploring the Applications of PLLs

In this article, we'll learn about several key applications of PLLs in communication systems, including tracking filters, frequency and phase modulation, and FM and AM demodulation.


Understanding the Hogge Detector and the Triwave Solution

Understanding the Hogge Detector and the Triwave Solution

The Hogge phase detector plays multiple roles in CDR circuits. In this article, we'll explore the Hogge detector's behavior, highlight its main drawbacks, and introduce a different configuration that addresses them.


Operation of a Linear Phase Detector for Clock and Data Recovery

Operation of a Linear Phase Detector for Clock and Data Recovery

Learn how the Hogge detector addresses the challenges of clock and data recovery (CDR) for data signals with limited clock information.


Using the Arduino Uno Q to Build a DDS Sine Wave Generator

Using the Arduino Uno Q to Build a DDS Sine Wave Generator

In this project, we'll construct and test a microcontroller-based system that digitally generates analog signals.


Projects Apr 19, 2026 by Don Wilcher
Introduction to the Gilbert Multiplier

Introduction to the Gilbert Multiplier

This article explores the Gilbert cell, a widely used analog multiplier circuit.


Second-Order Type-2 PLLs: Bode Diagrams, Bandwidth, and Overshoot

Second-Order Type-2 PLLs: Bode Diagrams, Bandwidth, and Overshoot

Learn how to select the zero frequency, damping factor, and loop bandwidth for one of the most popular PLL configurations.


Introduction to Second-Order Type-2 PLLs

Introduction to Second-Order Type-2 PLLs

This article explains how Type-2 PLLs with an integrator loop filter outperform Type-1 systems. To do so, we'll examine the PLL behavior for frequency step and frequency ramp inputs.


Introducing the Lag-Lead Filter

Introducing the Lag-Lead Filter

Learn how using a pole-zero loop filter improves PLL performance and design flexibility over the simpler lag filter.


Analyzing the Lag Filter’s Effect on PLL Performance

Analyzing the Lag Filter’s Effect on PLL Performance

In this article, we evaluate the designs of two simple frequency synthesizers to learn how a second-order PLL with a lag filter can provide a faster rise time than a first-order PLL.


Understanding the Limitations of the Second-Order Type-1 PLL With a Lag Filter

Understanding the Limitations of the Second-Order Type-1 PLL With a Lag Filter

In this article, we analyze the steady-state errors and Bode plots for a second-order PLL with a simple, first-order loop filter.