The Design Of Low Power Quad-Channels Digital-to-Analog Converter

The digital to analog converters (D/A converter) is used widely as the conjunctive circuit of digital electronic system and analog electronic system. So it's worth to design an D/A converter with the features of high speed, lower power consuming and high accuracy. A voltage-segmented D/A converter is designed which has voltage features of monotony.The input mode is serial-input, which meets the requirement of medium-speed; and the output mode is voltage-output, which could satisfy the demand of mass application. The chip is 8-bit which operates from a single +2.7V to +3.6V supply. There are quad-channels in chip. We can select channels to output by control-signal. Chip can be turn to shutdown mode by extern signal to decrease the power consuming. The supply current is 0.7mA while operating and 1μA in shutdown mode.The operational amplifier is designed, whose input and output swing rail to rail, which could satisfy the demand of D/A converter. For the design of the bandgap reference, the architecture of exponential curvature-compensated and the feedback circuit are employed, which satisfy the requirement of the low temperature coefficient (TC) and high power-supply rejection ratio (PSRR). The TC is 12ppm/℃, and the PSRR is 159μV/V.We run simulation with 0 .6μm BiCOMS process, and results of system simulation indicate that the INL and DNL of the DAC chip are both less than 1LSB, the settling time is less than 6μs.Design of each block is described. Performances of output operational amplifier and the bandgap reference circuit have a very deep influence on the D/A converter, so the research of the two parts'design is focused on. Layout consideration is also presented in brief and the simulation waves are given.