All About Circuits

Latest Modulation Articles and Videos

Categories

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.


Preventing Runt Pulses in Phase/Frequency Detectors

Preventing Runt Pulses in Phase/Frequency Detectors

This article explains the importance of incorporating delay into the feedback path of a phase/frequency detector (PFD) and examines its effect on performance.


Introduction to Phase/Frequency Detectors

Introduction to Phase/Frequency Detectors

Learn how using a phase/frequency detector (PFD) in place of a phase detector improves the acquisition range of a PLL.


Introduction to the RS Flip-Flop Phase Detector

Introduction to the RS Flip-Flop Phase Detector

Learn about this simple sequential phase detector and how it compares to the XOR gate. We'll also examine some key limitations and circuit implementations.


Understanding the Exclusive-OR Phase Detector

Understanding the Exclusive-OR Phase Detector

This article explores the operation of the simplest digital phase detector: the exclusive-OR (XOR) gate.


Diode-Based Phase Detectors: Key Principles and Example Circuits

Diode-Based Phase Detectors: Key Principles and Example Circuits

We examine phase detectors that leverage either the nonlinear characteristics or switching capabilities of diodes to perform multiplication.


Using Gilbert Multipliers as Phase Detectors in PLLs

Using Gilbert Multipliers as Phase Detectors in PLLs

This article explores the operation of the Gilbert-cell phase detector for both small and large signals.


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.


Understanding the Time-Domain Response of PLLs With Lag-Lead Filters

Understanding the Time-Domain Response of PLLs With Lag-Lead Filters

In this article, we examine how adding a zero to the PLL loop filter affects the transient behavior and steady-state errors.


Exploring the Bode Plots of PLLs With a Lag-Lead Loop Filter

Exploring the Bode Plots of PLLs With a Lag-Lead Loop Filter

In this article, we derive design equations for a second-order PLL with a lag-lead filter by examining its Bode plots.


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.


Knowledge and Nostalgia: 2025’s Top Educational Articles

Knowledge and Nostalgia: 2025’s Top Educational Articles

Ring in the new year with this roundup of All About Circuits' most popular educational content, both technical and historical.


News Dec 31, 2025 by Abby Garfinkle
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.


Introduction to Second-Order Type-1 PLLs

Introduction to Second-Order Type-1 PLLs

Learn how adding a lowpass loop filter to a PLL with a single integrator impacts both the frequency-domain and time-domain response.


Panasonic Industry PAN9019/PAN9019A | Featured Product Spotlight

Panasonic Industry PAN9019/PAN9019A | Featured Product Spotlight

Panasonic Industry PAN9019/PAN9019A delivers high-performance, low-power connectivity with dual-band Wi-Fi 6, Bluetooth 5.4, and—on the PAN9019A—802.15.4 support for expanded IoT applications. Watch and learn all about their features, specs, applications, and more!


Understanding the Limitations of the First-Order PLL

Understanding the Limitations of the First-Order PLL

Higher-order PLLs are more commonly used than first-order PLLs. To explain why, we explore the first-order PLL's behavior in response to two inputs: a frequency step and frequency ramp.


Analyzing First-Order PLLs Using Linear Models

Analyzing First-Order PLLs Using Linear Models

In this article, we'll use the linearized model of a first-order PLL to understand its response to a simple input change. We'll then use Matlab simulations to visualize the signals.