Design Of A 12-Bit Segmented Current Steering DAC Based On DWA

Digital to analog converter is an important part in the digital-analog mixed signal system, it has a widely use. The dissertation introduces the design of a 12-bit segmented current steering DAC based on data weighed average algorithm (DWA). At the present time, digital to analog converter use the current steer configuration mostly and the segmented configuration thereinto is fit for the design of high-speed, high-precision DAC. But due to the technic error, it is hard to guarantee the matching of current sources, we use data weighed average algorithm to solve the problem.The dissertation introduces the system configuration of the three segmented DAC firstly, the configuration considers the chip area and the performance, and introduce the main factors which confine the performance of the DAC, and designs all the parts of DAC according to the above. The dissertation designs a band gap reference which has a 5.44ppm's temperature coefficient, designs a current source with high output resistance, and designs a DWA block base on full adder to solve the non-matching of the current source. For the difference output, designs a current switch signal generator with high cross-point and restricted voltage range to decrease the glitch of output, in order to obtain a good dynamic performance. At last, analyses the frequency performance and to the DWA block the dissertation gives a non-matching to the current sources, it proves that the DWA is useful to the improvement of dynamic performance.The dissertation designs a 12-bit"4-4-4"segmented current steering DAC. The 4 highest bits and the 4 middle bits uses the thermometer configuration, and the 4 low bits uses the binary configuration. It uses two power supplies to supply power to digital part and analog part. It uses the Hejian Technology 0.18-micron technic.