A symphony of precision: Harmonizing power and signal integrity with low-noise technology

In the summer of 2004, a standard ultrasound showed that Steve and his wife were expecting twins. But a few weeks later, they were surprised to find that they were expecting triplets. Steve, a systems engineer in the Switching Regulator Division at Texas Instruments, suspected that unwanted noise or signal interference in the ultrasound system was likely causing the anomaly.

“I never really realized it until I started working with medical imaging devices and wireless infrastructure, where noise is a big issue,” said Steve, whose triplets are now grown and preparing for college.

It has been nearly 20 years since Steve encountered the anomaly in ultrasound inspection. Technology has advanced significantly over the years. However, finding ways to reduce system noise and improve signal quality to achieve a precision signal chain continues to be a challenge for design engineers across many industries.

Understand the negative effects of noise on system performance

In the operation of complex power systems, the absence of noise is an ideal state, but it is difficult to achieve. Noise is an electrical product generated by all components and can come from many sources, including electromagnetic interference (EMI) and heat. Noise can corrupt signals and cause distortion in measurements, which can lead to errors, miscalculations or misinterpretations, ultimately affecting the accuracy and reliability of the system.

Noise also makes electronic systems more susceptible to external factors such as temperature fluctuations and voltage changes. These external factors can further amplify the noise, adding additional errors.

In sensitive systems such as medical imaging equipment, excessive noise can cause blurry images or potentially lead to inaccurate images. Noise can also negatively impact the accuracy and precision of test and measurement equipment, leading to inaccurate results.

Building electric vehicles with high precision

Noise challenges are particularly important to automotive engineers designing electric vehicles (EVs) or developing autonomous driving systems where precision signals are critical to safety and performance.

“In electric vehicles, sensitive systems used for safety or parking functions are susceptible to excessive noise, and these systems are in close proximity to high-power components that generate noise,” said Jeff Morroni, director of power management R&D at Kilby Laboratories, an applied research laboratory of Texas Instruments. “This is exactly the problem our low-noise and high-precision technology is trying to solve.”

Sensitive systems need to be robust enough to withstand noise generated by heat and physical stress. The stress generated when a car hits a speed bump is enough to affect signal accuracy. Noise can affect the operation of autonomous driving systems, and light detection and ranging (lidar) systems can experience "ghosting" problems, that is, the generation of false or misleading signals or images. Meanwhile, the lithium-ion batteries that are powering the electric vehicle revolution can become unstable and pose safety risks if they overheat.

Power management devices used in the signal transmission and conditioning chain are critical to achieving a clear signal by minimizing distortion and noise. These power devices can also power clock ICs as well as precision ADCs (analog-to-digital converters) and DACs (digital-to-analog converters), completing a complete low-noise and high-precision signal chain.

A more specific benefit of reducing noise is extending the range of electric vehicles. The more accurately developers can measure the voltage signals of electric vehicle batteries, the longer the electric vehicle can travel on a single charge. High-precision battery monitors and balancers that measure down to millivolts (thousandths of a volt), such as the Texas Instruments BQ79718-Q1, can significantly extend driving range.

“We’re talking about 10% to 15% extended range, which is achievable simply through more accurate voltage measurement,” Jeff said. “This directly reduces the cost of the battery and meets the customer’s value proposition.”

Reduce design time and costs with low-noise technology

To achieve greater noise reduction, it is necessary to examine each link in the signal chain. Semiconductors themselves generate noise that affects the performance of other components. However, this noise can be "canceled" using passive filtering, control techniques, and other unique process technologies. In addition, power components such as low-noise low-dropout regulators (LDOs), buck converters, and voltage references can also help achieve low system noise.

For decades, low noise LDOs have been the industry standard for providing low noise power due to their ease of integration and ability to provide ultra-clean, ultra-precise power rails for highly sensitive applications. For example, Texas Instruments' TPS7A94 offers the lowest output noise power supply on the market, high output voltage accuracy, and ultra-high power supply rejection ratio, generating clean power rails that do not affect system performance.

Meanwhile, the Texas Instruments TPS62913/2 series of step-down converters can reduce noise in power structures without the need for a traditional LDO to regulate the voltage. Although it may generate slightly more noise than an LDO, it can save space and cost, improve efficiency, reduce power consumption and reduce thermal issues.

As a fundamental building block in data conversion systems, voltage references also play an important role in reducing noise. Voltage references require excellent stability to avoid introducing errors into the signal chain. Texas Instruments' REF70 ultra-high precision voltage reference sets an excellent low-noise benchmark, unlocking extra bits of the ADC and enabling precise measurements.

Katelyn said, “I think voltage references are the cornerstone of signal chain design because every component, whether it’s an ADC or a DAC, must be referenced to a voltage. Reducing noise is very important because a lot of noise can cause a system to measure out of specification. If that happens, you have to take the entire system offline to debug and calibrate. If we can extend the calibration cycle, we can provide our customers with higher throughput and less downtime, which really provides value to them.”

Although noise is an unavoidable product of power architecture, by using low-noise and high-precision technologies from Texas Instruments, engineers can design systems with small size and excellent accuracy at a lower cost.

“As a father of triplets and an engineer, I’ve seen firsthand the significant impact noise has on sensitive systems in many applications,” said Steve. “For the past 18 years, TI has been committed to advancing noise reduction technology, but there are still many challenges. Our continued innovation helps engineers overcome these challenges, resulting in significantly improved system performance.”