A 280 mW, 0.07% THD+N class-D audio amplifier using a frequency-domain quantizer

Junghan Lee, Tino Copani, Terry Mayhugh, Bhaskar Aravind, Sayfe Kiaei, Bertan Bakkaloglu

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Pulse density modulation (PDM) based class-D amplifiers can reduce non-linearity and tonal content due to carrier signal in pulse width modulation based amplifiers. However, their low-voltage analog implementations also require a linear loop filter and a quantizer. A PDM based class-D audio amplifier using a frequency-domain quantization is presented. The digital intensive frequency-domain approach achieves high linearity under low supply regimes. An analog comparator and a single-bit quantizer are replaced with a current controlled oscillator (ICO) based frequency discriminator. By using the ICO as a phase integrator, a third-order noise shaping is achieved using only two analog integrators. A single-loop, single-bit, class-D audio amplifier is presented with an H-bridge switching power stage, which is designed and fabricated on a 0.18 μm CMOS process with 6 layers of metal achieving a total harmonic distortion plus noise (THD+N) of 0.065% and a peak power efficiency of 80% while driving a 4-Ω loudspeaker load. The amplifier can deliver the output power of 280 mW.

Original languageEnglish (US)
Pages (from-to)173-186
Number of pages14
JournalAnalog Integrated Circuits and Signal Processing
Issue number1
StatePublished - Jul 2012


  • Audio amplifiers
  • Class-D amplifiers
  • Frequency discriminators
  • Sigma-delta modulation

ASJC Scopus subject areas

  • Signal Processing
  • Hardware and Architecture
  • Surfaces, Coatings and Films


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