Abstract: In view of the current poor precision signal generator frequency  adjustment shortcomings,the paper provides  a PID algorithm to achieve high-precision frequency step scale new methods;with the  combination of MCU and  D/A,a multi-frequency wave-form signal generator has been designed,with a signal at 5 Hz～20 MHz frequency range and relative error of less than 0.05%.

Key words: PID algorithm, MCU, digital control