Design of Three-Stage Class-AB 16 $\Omega$ Headphone Driver Capable of Handling Wide Range of Load Capacitance

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> In this paper, the effect of load capacitance variation on the location of the closed loop poles of three-stage amplifiers is analyzed and a frequency compensation scheme that automatically adjusts the damping factor according to the load capacitance is proposed. A class-AB 16 <formula formulatype="inline"> <tex Notation="TeX">$\Omega$</tex></formula> headphone driver designed using the proposed scheme in 0.13 <formula formulatype="inline"><tex Notation="TeX">$\mu$</tex> </formula>m technology can handle 1 pF to 22 nF capacitive load while consuming as low as 1.2 mW of quiescent power. It can deliver a peak power of 40 mW (1.6 Vpp swing) to the load with <formula formulatype="inline"><tex Notation="TeX">${-}$</tex> </formula>84.8 dB THD and 92 dB peak SNR. It occupies 0.1<formula formulatype="inline"> <tex Notation="TeX">$~$</tex></formula>mm<formula formulatype="inline"><tex Notation="TeX">$^{2}$</tex></formula> area. </para>