Seminar 050314 Brett Forejt

A “battery connect” compatible class D (switching) amplifier which is fully integrated in a 90 nanometer digital CMOS process is presented. The integration of the amplifier requires no additional masks, processing, or cost. This paper includes a brief description of the circuit techniques that enable direct battery (2.7 – 5.4V) connection and allow support > 6.7 VP2P (700 mW into 8 ohms) output swing from a 4.2 V supply using devices that operate solely with low gate voltages. The achieved SNR over an audio (20Hz to 20 kHz) bandwidth > 93dB and the total harmonic distortion (THD) is better than 0.03% at 500 mW. Efficiency is greater than 75% above 375 mW. The power supply rejection ratio (PSRR), which is a crucial parameter in modules connected directly to the battery, is measured at 70dB at 217 Hz. The area of the switching amplifier is < 0.44mm2, where the power devices occupy approximately 20% of the total.

Brett Forejt graduated from Carnegie Mellon University in 1995 with his BSEE and graduated from Oregon State University in 1998. Brett has over 9 years of industry experience in analog and mixed signal design starting in 1995 with Hewlett Packard Corp. In 1997 He joined Texas Instruments Inc. working specifically in wireless telephony. Brett is a Member Group Technical Staff at Texas Instruments Inc. in the Wireless Terminals Business Unit and a member of IEEE.