A filter free class D audio
amplifier with 86% power
efficiency
Muggler, P., Chen, W., Jones, C., Dagli, P., Yazdi, N.,
ISCAS '04. Proceedings of the 2004 International Symposium on
Circuits and Systems, 2004.
Volume 1, 23-26 May 2004 pp.I - 1036-9 Vol.1
指導老師：易序忠
學
生：楊正元
國立彰化師範大學積體電路設計研究所
Outline
 Abstract
 Schematic
 Result
Abstract
 2.5W output power and 86％ efficiency with
an 8 ohm load.
 It operates with a 2.5 V to 6.5 V supply
voltage in a 7V, 1.2 um, double-poly, triplemetal, BiCMOS process.
 It has an area of 1.5 x 1.5 mm2 and it
achieves a THD as low as 0.04%, with a
flatband response between 20 Hz and 20
kHz.
Modulation Scheme
 Double-sided natural sampling pulse width
modulation scheme.
 The selected PWM scheme provides current
to the load only when needed, and once
delivered the current is maintained. This is
accomplished by using all four states
available to a full H-bridge. The modulation
scheme uses any of the states in any order,
dependent upon the audio input signal.
Different kinds of PWM modulations
Advantage
 The amount of information contained
in each period is twice the amount of
single sided modulation.
 There is the possibility of having all of
the significant distortion components
to be outside the audio band thus
enabling a filter free class D audio
amplifier.
Signal Spectrum showing Distortion
Components
Schematic of the Designed Class D
Audio Power Amplifier
Cross-Coupling
Example
Efficiency versus Power Curve
Total Harmonic Distortion versus
Power Curve
Die Photo
SUMMARY OF MEASUREMENT
RESULTS
Thank you for your
patience.