On-Chip Voice-Coil Motor Driver for Mobile Auto-Focus Camera Applications

On-chip voice-coil motor (VCM) driver for mobile auto-focus (AF) camera applications is proposed and integrated into image signal processor (ISP) satisfying small size and low-power consumption. In order to control the location of AF lens, a charge pump (CP) or digital-to-analog converter (DAC) can be selected. Since a large current is required to drive the VCM, the buffer amplifier was inserted after charge pump or DAC. On-chip VCM driver is fabricated using a commercial 0.18 mum CMOS technology. As the result, the chip shows the fast speed enough to operate with 30-fps image signal processor and the quiescent current consumption of 0.32-mA