TI Rolls Out New ADC for Improved Voice Capture in Noisy, Far-field EnvironmentsNovember 05, 2019 by Lisa Boneta
TI designed the new ADC to capture low-distortion audio recordings from far distances or in noisy environments.
Many smart speaker owners understand the frustration of yelling at an unresponsive smart home device after you've asked about the weather, requested a song, or added eggs to the grocery list—sometimes multiple times. Manufacturers of analog-to-digital converters (ADCs) are working to overcome the challenge of microphones "mishearing" a human voice, either because of soft tone or distance.
Texas Instruments' New Burr-Brown Audio ADC
Texas Instruments has produced a new ADC that is reported to capture clear audio up to four times further than competing ADCs. The TLV320ADC5140 is the newest member of the TI Burr-Brown family of audio ADCs that enable far-field, high-fidelity recordings in any environment.
The TLV320ADC5140 is available at the TI in a 4-mm by 4-mm, 24-pin wafer quad flatpack no-lead (WQFN) packaging.
The TLV320ADC5140 enhances audio capturing despite a limited number of microphones, environmental noise, and limited signal processing. Image from Texas Instruments
Abhi Muppiri, one of TI's audio products marketing engineers, explains that while "most analog microphones deliver about 106–108 dB," the new TI ADC "is able to capture 120 dB performance." Muppiri explains, "This enables us to provide crystal clear, obstruction-free audio performance in any environment—be it a noisy environment or be it a situation where the audio speaker itself is blasting full volume."
Features of the TLV320ADC5140
Clear Audio Capture in Any Environment
With a built-in 120-dB dynamic range enhancer (DRE), the ADC boosts low-volume audio signals, which enables low-distortion recordings even in far-field, noisy environments.
TI's new ADC is designed to support the latest premium analog microphones. Image from Texas Instruments
The far-field voice capture works at distances greater than 10 meters away.
Premium-quality Voice Compatibility with High SNR Microphones
TI titles the TLV320ADC5140 as the first ADC to fully support the latest high signal-to-noise (SNR) ratio microphones with a dynamic range greater than 106-dB. SNR is the ratio of signal power to noise power (desired sound versus undesired sound in the case of a microphone). A higher SNR means that the device picks up more desired sound than undesired noise. In voice capture technology and devices, having a high SNR allows the device to discern between a loud TV blasting in the background—or even music blasting from its own speakers—and a human voice. ADC and SNR microphone compatibility is vital to optimal performance.
"If a user is speaking to a smart speaker in a very low voice, our ADC can detect the lowness of the voice and amplify it on-chip," Muppiri states. "So, instead of the user yelling at the smart speaker, we’re amplifying the sound of their voice for them."
Integration and Programmability to Enable Versatile System Design
The TLV320ADC5140 offers wide design flexibility, working with systems with up to four analog microphones or eight digital microphones, or a combination of the two. Discussing the ADC's flexibility with both analog and digital mics, Muppiri explains that design engineers "can use the part in their early prototyping or evaluation stages," which gives them the choice between "a high-power option and a low-power option."
Other programmable features include gain calibration with 0.1-dB resolution, phase calibration with 163-ns resolution to equalize microphone-array mismatches, gain amplification, high-pass filters, channel mixing, and linear phase or ultra-low-latency decimation filters. Because the TLV320ADC5140 is compatible with many devices, designers can use it for a vast array of audio-recording applications.
Muppiri claims that TI has "customized features [engineers] would otherwise need externally and brought it back into the system, which gives them an advantage in terms of integration."
Small Size and Low-power Consumption
Using the TLV320ADC5140, designers can offload digital signal processing tasks, which in turn allows for more compact designs without compromising system reliability.
Functional block diagram of TLV320ADC5140. Image from Texas Instruments
Power consumption for 1.8 V AVDD supply is only 9.2 mW/channel at 48-kHz sample rate and 8.5mW/channel at 16-kHz sample rate.
The Future of Audio and Voice Innovation
Many consumers interact with microphones in a variety of devices: hands-free devices in the car, smart speakers at home, conference call devices at work, and mobile speakers on the go.
TI's new ADC opens a number of innovative possibilities in voice-capture systems. For instance, the TLV320ADC5140 may be used to improve microphone quality in vehicles, implementing multiple microphone inputs throughout the passenger compartment to help enhance communication with the interactive car speakers. TI's Burr-Brown audio ADCs can also enable intelligent microphone systems in conferencing systems to estimate the number and direction of speakers in the room, activate only the microphone facing the speaker, and shut off all other microphones to eliminate noise.
Audio converters motherboard (AC-MB) + ADC5140EVM-PDK TLV320ADC5140 quad-channel 768-kHz Burr-Brown ADC evaluation board. Image from Texas Instruments
Muppiri sees promise in how designers might use TLV320ADC5140 to receive the "best of quality, performance, and price."
With improvements to ADCs, such as those offered by the TLV320ADC5140 and the TI Burr-Brown family, designers and consumers can expect to see improvements in voice-recognition applications.
How do you work with ADCs? Let us know in the comments below.