Analog Design Journal

Choosing a position sensor in motor control

By Isaac Lara, Manny Soltero, Martin Staebler and Yufeng

Despite the trend for some systems to go “sensorless,”
there is still a need for position sensors in BLDC motor commutation, servo drives and encoders. Various devices such as latches, 1D linears and angle sensors are used in motor control to inform the  microcontroller of the position of the rotor shaft to address torque efficiencies and speed control. We will  discuss technologies used as position sensors, such as Hall-effect, anisotropic magnetoresistive (AMR) and inductive, how to use them and summarize the benefits and drawbacks to each.

Cascaded ideal diodes: Solving 48V EV power challenges

By Shiven Dhir and Rakesh Panguloori

This article presents a cascaded ideal diode configuration using two series controllers driving 60V MOSFETs to effectively manage high differential voltages in 48V automotive systems while meeting the LV148 standard's 70V load-dump requirement. To enhance reliability margins, we introduce a ground-side level shifting circuit that extends operational capability under load dump conditions. The proposed solution provides robust input protection while enabling manufacturers to use cost-effective, multi-sourced 60V MOSFETs, thereby addressing key challenges in automotive power distribution systems.

A novel approach to narrowband matching high-speed RF ADCs

By Rob Reeder

For applications that don’t require gobs of bandwidth (BW), ie – wideband sampling, where 1 to 2GHz or more, are required. Designing a narrowband (NB) match, ie – where only 100s of MHz is required, with a balun or transformer frontend circuitry for an analog-to-digital converter (ADC) can still be challenging. This is especially non-trivial in systems with high intermediate frequencies (IFs) that are often digitized in modern communications and/or radar systems to perform signal processing in the digital domain. In this article, we describe a simple and easy process to get the most out of your ADC without a lot of simulation downtime. Here, we will uncover in only a few simple steps how to resolve 100s of MHz of BW at any baseband or IF location, as long as it sits within the ADCs own rated BW of course.

Comparing discrete and integrated difference amplifiers

By Esteban Garcia and Jacob Nogaj

Difference amplifiers (DAs) come in two forms: discrete (using external resistors) and integrated (with on-die resistors), with the latter offering superior performance in critical parameters. Integrated DAs demonstrate significantly better common-mode rejection ratio, lower gain error and more stable gain error drift across temperature fluctuations due to their interdigitated resistors that "drift together." While discrete DAs offer flexibility in selecting operational amplifiers, integrated solutions provide exceptional performance for voltage monitoring beyond supply rails for applications such as solar panels, power banks and DC/DC modules in noisy industrial environments. Test results confirm integrated DAs consistently outperform discrete implementations across various operating temperatures.

Designing real-time diagnostic (RTD) circuits for automotive audio applications

By Jared Becker

This article addresses the growing demand for real-time diagnostic capabilities in automotive audio systems, particularly for monitoring Class-D amplifiers and speakers connected to telematics control units critical during emergencies. The article details how a Class-D audio amplifier can be enhanced with additional circuitry and a baseline 5Hz signal to achieve comprehensive real-time diagnostics for all four major speaker fault conditions: shorts to ground, shorts to battery, output-to-output shorts and open loads. This implementation ensures immediate fault detection during vehicle operation without introducing audio artifacts, significantly improving safety by allowing prompt notification of speaker failures that could compromise emergency communication systems.