Design Principle of the Precision Digital Control Reference Voltage Source

Reference voltage source is a high stabilization voltage source as a sort of voltage standard, used abroad in digital instrument, intelligent instrument and test system at present. At the auto-control domain, often need one output voltage adjustable precision reference voltage source to control the action of the execute machine. The characteristic of the digital control reference voltage is precision setting or adjusting the reference voltage by the keyboard of the single chip micro-computer or the micro-processor, and between the reference voltage and the input number has strict corresponding relation. By the theory of the band gap reference voltage using the positive temperature of the resistor to compensate the negative temperature of the emission of the transistor, thereby realized zero temperature, bring forward two design project for the precision reference voltage source: the first project is replaced resistor by digital potentiometer, which can adjust the reference voltage directly, its shortcoming is as the limit of the inner number and the error of the cell resistance within the digital and the wiper resistance, the adjust precision is not very high; the second project is using with reference voltage source and voltage converter high differentiate D/A converter, and with the single-chip micro-computer, composed precision reference voltage, its strongpoint is circuit simple, can get 8192 types different value of the reference voltage, the temperature coefficient of the output reference voltage is 16 x 10^-6/degC,which can satisfy the design. The expatiated design project has practicality value.