CSR strengthens audio platform with high fidelity class-D amplifier technology

CAMBRIDGE, ENGLAND & SUNNYVALE, USA: Extending and enhancing its audio platform offerings, CSR plc announced the acquisition of Direct Digital Feedback Amplifier (DDFA) technology, a proprietary, highly scalable digital Class-D audio amplifier technology which will allow CSR to offer a broader, more complete range of audio solutions to OEMs that dramatically simplify system designs and reduce cost while achieving unsurpassed audio quality.

The innovative DDFA technology will enable CSR to provide complete, high-performance, all-digital audio processing pipelines, from source to speakers, for a variety of wireless and wired active speakers, speaker docks, sound bars and other consumer audio products.

“This patented DDFA technology now gives us the unique ability to produce incredibly compact digital power amplifier stages that combine the high energy efficiency of Class D operation with output sound quality that until now has only been possible with the very best linear amplifiers,” said Anthony Murray, senior VP for the Home Business Group at CSR. “With the acquisition of DDFA technology, CSR will be able to provide a complete audio platform solution to address the needs of our customers in existing and emerging new markets for wireless audio. We believe the DDFA technology will enable us to ultimately offer our customers a broad range of truly all-digital audio solutions that deliver significant cost and quality benefits over traditional designs, and which will spark entirely new consumer product categories.”

The acclaimed NAD VISO 1 Wireless Digital Music System from NAD Electronics is a prime example, where DDFA technology has been selected as the amplifier solution. Greg Stidsen, Director of Technology and Product Planning of NAD explains: “DDFA is the ideal digital amplifier technology to meet our performance needs while at the same time providing the processing features that allow our engineers to perfectly optimise the system’s acoustic performance.”

DDFA technology benefits
The DDFA architecture employs a fast and highly accurate digital feedback loop to create a Class-D audio switching amplifier that sets new standards in digital amplifier sound quality. Even when used with an inexpensive, unregulated power supply, including switching power supplies, digital amplifiers based on DDFA technology can achieve THD+N performance levels of less than 0.004 percent and a dynamic range of 120dB, according to our internal studies.

The DDFA architecture is highly scalable in terms of power output, number of channels and the range of applications it is suitable for. Implementations with today’s chipset are able to produce 20 to 250 Watts with up to eight single-ended or four bridge-tied load channels using a single modulator, with flexible combinations of modulators and feedback processors allowing a variety of channel counts to be implemented. Applications cover the entire range of consumer audio products, from docking stations, active speakers and sound bars to premium AV receivers, component high-fidelity amplifiers and home entertainment systems.

Unlike more traditional linear amplifier solutions, the DDFA architecture integrates the functions of DAC, DSP, pre-amp and power amp to significantly simplify system design, maintain signal integrity and reduce cost. DSP capability includes dedicated configurable IIR filters supported by mix/map functions to implement active crossovers and parametric EQ for room or cabinet equalization. Conventional functions such as tone and volume controls also benefit from the full digital implementation, avoiding the degrading side-effects seen in analogue implementations.

Advanced power management features enable the DDFA architecture to provide intelligent short-circuit protection, programmable clip management, dynamic compression, configurable power and current limiting.

DDFA technology from CSR is already deployed in mass-produced consumer audio products.