The Design Of 10-Bits Digital-to-Analog Converter

The 10-bits digital-to-analog converter (DAC) is developed for the company. The circuit is the medium scale digital and analog mixed integrated circuit. The positive design method and inverted design method are applied to the design. According to the analysis of AD7520, the R-2R resistors network and the analog switch section are designed with inverted method. Since there is not the referenced voltage circuit, we have read a lot of information and designed a kind of bandgap source integrated with AD7520.This design is based on the CSMC 0.6μm CMOS N-well DPDM (Double Poly Double Metal) process. The work includes negatively analyzing the chip, extracting the circuit investigating the principle and simulating the circuits, the excellent function and performance are attained with the 0.6μm process adopted. The bandgap is designed with positive method, the basic function of the bandgap is analyzed, and the design of the operation amplifier is in detail discussed in the thesis. Then, the structure of the whole DAC is constructed and simulated, and the simulation results are obtained. Finally, the layout of the whole DAC is accomplished based on the character of digital and analog mixed signal layout design. The DRC and LVS have done, and the parasitical parameters are extracted to make the post-simulation.All works are carried out with the personal computer in this thesis. The Workview office is applied to design the circuit, the L-EDIT is adopted to design the layout, and the HSPICE is used to simulate the function and performance of the circuit and the layout. The function of digital to analog conversion is realized with the designed DAC. The working voltage source is 5V single power supply, the resolution reaches 10-bits, the sample frequency is 50 kHz, the power consumption is only 4.32 mW, the layout area is 0.8 mm~2, the minimum INL is 0 LSB, the largest INL is +2.53 LSB, the minimum DNL is -0.47 LSB, and the largest DNL is +0.46 LSB, the output voltage of bandgap is 3.3V, the zero temperature coefficients point is 27℃.