OnQ Blog

Premium audio quality in a Class D amplifier: more about Qualcomm DDFA

Oct 4, 2017

Qualcomm products mentioned within this post are offered by Qualcomm Technologies, Inc. and/or its subsidiaries.

In June this year, we released the latest version of our Qualcomm DDFA Digital Amplifier technology. The result of more than ten years of R&D, it’s designed to perfectly balance the power efficiency of Class D devices, alongside the high-performance audio output of traditional, linear amplifiers. What helps differentiate Qualcomm DDFA from other Class D amps is that it can support a truly premium listening experience.

Why we designed Qualcomm DDFA

Class D amplifiers have helped revolutionize the audio industry by bringing power efficient amplification capability to smaller form factor devices. This means that hi-fi audio systems can be made more compact, and portable speakers can be played more loudly for longer.

While Class D amplification is designed to deliver major benefits, some audio aficionados are skeptical of the technology due to several factors, including:

  • Class D amplification is based on a technique called Pulse-Width-Modulation (PWM) which was originally designed to control high-speed motors. PWM signals tend to be noisy and imperfect resulting in a less than desirable listening experience.
  • When played at high volumes Class D amplifiers place high demand on the power supply, resulting in voltage drops and some class D amplifiers are unable to support optimum audio quality in these conditions.
  • Nowadays to connect amplifiers to digital music streams, for example from the Internet, a Digital-to-Analog (DAC) convertor is required which can also contribute to degradation of the audio signal and negatively impact user enjoyment.

Because audio is in our DNA and we’re passionate about helping to deliver leading audio technologies that make a difference to people’s lives, we decided to develop our DDFA technology solution to help improve the performance of Class D amplifiers, so that more people can enjoy premium hi-fi audio.

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What’s so special about Qualcomm DDFA?

Patented closed-loop digital architecture

DDFA stands for “Direct Digital Feedback Amplifier” and is based on a patented closed-loop digital architecture that is designed to provide multiple advantages over traditional analog class D amplifier solutions. Here’s how:

  • Because DDFA is digital, the PWM modulator can be made significantly better than its analog equivalent, introducing less noise.
  • Being digital also removes the need for a DAC on the input which helps to lower the chances of audio degradation and jitter in the system.
  • DDFA is designed to monitor the voltage of the power supply and adjust the PWM modulation accordingly, helping devices to maintain performances at maximum volume.

Closed-loop operation is not unique to Qualcomm DDFA, but what makes our solution different is our proprietary analog feedback processor technology — a feature that helps to maintain the audio performance consistency. This means speakers built with our technology can help to consistently deliver industry-leading audio performance across the entire audio frequency band and at maximum volume:

  • Signal to Noise Ratio and Dynamic range > 113dB (A-weighted, 20Hz to 20KHz)
  • THD+N < 0.005% (20Hz to 20KHz)
  • Virtually no audible noise, even at maximum volume

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Advanced DSP features

Along with a patented core architecture, our next generation DDFA technology integrates an advanced configurable DSP with 32bit PCM up to 384KHz and DSD64/128 input, integrated high-resolution interpolation filters, and equalizers. This powerful feature can help manufacturers build speakers that support high-resolution audio without the need for additional, external devices.

Our commitment to help deliver leading audio technologies

With the release of the next generation of Qualcomm DDFA, we’ve made our industry leading speaker technology available to a broad range of audio brands. We hope that this will help them deliver a greater choice of digital speaker products with high quality sound for all consumers to enjoy, including lovers of premium audio.

Qualcomm DDFA is a product of Qualcomm Technologies International, Ltd.

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