Digital oscilloscope analog channel direct current gain field calibration method

The invention discloses a direct current gain field calibration method for an analog channel of a digital oscilloscope, and the method comprises the steps: enabling a microprocessor (MCU) to control a DAC module to generate a low-frequency square-wave voltage signal at the front end of the channel as a calibration source on the basis of the hardware of an existing shift voltage regulation circuit of the analog channel, and constructing a shift calibration circuit based on a bias voltage source, under different amplitude gears, off-site calibration and calibration are firstly performed on the digital oscilloscope, the amplitude of a calibrated low-frequency square wave signal in a digital format is stored, and then field calibration is performed after the digital oscilloscope arrives at the field and before the digital oscilloscope is used: the stored low-frequency square wave signal is read as a calibration source (calibration square wave signal), and field calibration is performed on the direct current gain