A 10-bit 0.64 to 1.27-mW 20-MS/s Hybrid Dgital-to-Analog Converter with a Power Control Logic

Abstract

For medical implantable devices, power consumption is the most important design factor to be considered. In order to achieve low power consumption with medium data rate and resolution, this paper proposes a resistor-string and current-steering hybrid digital-to-analog converter (R-I DAC) with a power control logic. This R-I DAC adopts a resistor-string sub-DAC as the least-significant-bits (LSBs), and uses a current-steering sub-DAC as the most-significant-bits (MSBs). The current-steering sub-DAC is controlled by a power control logic to improve the power efficiency. The power control logic is to shut off the current through the source transistor if the output voltage is low. Before the output voltage changes from low to high, the current is turned on ahead of approximate one clock circle. The power reduction percentage of R-I DAC depends on the output, e.g. it reduces 27.7% for output all 0’s and 6% for a sine wave output. The proposed 10-bit R-I DAC shows faster speed than resistor or capacitor based DACs with sub-1mW power consumption. The rise time is measured, which is 50ns. The measured DNL/INL without calibration is 0.8/1.5 LSB. The static power consumption of lowest and highest voltage output are 0.64 mW and 0. S6mW, respectively. The total power consumption is 1.27 mW when the input is 1 MHz sine wave with 20 MS/s sampling rate.