Nieke Roos
12 February

The Enschede chip startup continues its digital audio amplifier revolution under American wings.

US-based Monolithic Power Systems (MPS) has announced the acquisition of Axign, the fabless semiconductor startup from Enschede that specializes in audio controller chips. According to the Dutch company, its programmable multicore DSPs demonstrate near-zero distortion signals with significantly reduced power consumption, revolutionizing signal processing and amplification for automotive and consumer audio systems. MPS plans to expand its presence in the Netherlands, leveraging Axign’s established local connections, in particular to the University of Twente.

Axign took off in 2014 with patented technology from Axiom IC. This renowned UT chip design spinoff had been bought by US semiconductor powerhouse Teledyne a year earlier. Jeroen Langevoort worked at Axiom-IC at the time of the acquisition. “We had developed an audio technique that the Americans had no use for so we asked them if we could start our own company with it,” the Axign founder told U-Today in 2017, when his startup had just finished its first product, the AX5689 4-channel digital-input Class D audio controller (links in Dutch).

Successful journey

The AX5689 compares the analog signal after the output filter, at the speaker terminals, with the digital input signal. All disturbances in the loop, such as power stage dead times, power supply ripple and non-linearity from the output filter, are directly suppressed thanks to the high digital loop gain. The analog signal at the speaker is converted using a high-performance feedback ADC, which combines a low latency of several nanoseconds, for loop stability, with a high dynamic range of up to 120 dB on set level for consumer audio solutions like streaming amplifiers, smart speakers and TV soundbars.

With only the converter’s input stage in the analog domain, the AX5689 is highly digital and consequently has all the accompanying features like programmability, self-learning and robustness. Being highly digital, the chip is insensitive to component tolerances. This allows for high-order loop filters, up to 7th order, enabling a high open-loop gain and steep filtering. The ability to program the transfer function loop makes it easy to change filter characteristics, for example noise shaping from 20 to 40 kHz and vice versa. The result is a Class A audio performance at Class D efficiency, size and cost.

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The introduction of the AX5689 marked the beginning of an extremely successful journey, leading to the acquisition by MPS. In 2020, Axign announced its first A-brand design-win with American home entertainment powerhouse Harman Kardon integrating the AX5689 into its new stereo streaming amplifier. A year later, the startup got a 12-million-euro bump in funding to accelerate the commercialization of its products. In 2022, it revealed a next-gen GaN-based 500 W Class D audio amplifier together with Canada’s GaN Systems.

Not only audio

“When I listened to music from an Axign amplifier, I instantly recognized the excellent sound quality – the rich texture, wide dynamics and clear spatial resolution,” says Michael Hsing, the founder and CEO of MPS. “I realized that combined with our technologies, we can bring that audiophile quality to the mass market. Their passion for delivering best-in-class performance products matches our culture. Axign will also bring its expertise and innovation not only to the audio market but also to other applicable fundamental technologies for different market segments.”

Headquartered in Kirkland, Washington, MPS is a fabless global company that provides high-performance, semiconductor-based power electronics solutions. Founded in 1997 by Hsing, it has three core strengths: deep system-level knowledge, strong semiconductor design expertise and innovative proprietary technologies in the areas of semiconductor processes, system integration and packaging. These combined advantages enable MPS to deliver reliable, compact and monolithic solutions that are highly energy-efficient, cost-effective and environmentally responsible.

Main picture credit: Axign