Oscilloscope Calibrator Calibration Signal Circuit Design

As the standard signal generator, Oscilloscope calibrator is used to calibrate the specifications of the Oscilloscope. In this paper, calibration signal generator circuit of oscilloscope calibrator is designed to generate six kinds of signals calibrating some of the major indicators of 100MHz Oscilloscopes. which are DC signal for amplification calibration, low frequency square-wave signal for amplification calibration, sine-wave signal for frequency calibration, square-wave signal for time calibration, fast square-wave signal for edge calibration and triangle-wave signal for trigger calibration.But the majority of high-performance signal sources realizes now through the frequency synthesis technology. The frequency synthesizer uses or many standard signals, produces the massive discrete frequencies signal equipment through each technical way.The traditional frequency synthesizer has the direct simulation synthsis and the phase-locked loop synthesis two kinds.The direct digital frequency synthesizes(DDS) is one kind of new frequency synthesis technology which the recent years developed.Its main merit is the relative band width is very wide,the frequency switching time is extremely short (may small than 100ns),the frequency resolution is very high,theentire digitized structure is advantageous for the integration,the output phase continuously,the frequency,the phase and the scope may realize the program control.Therefore,can unify closely in with the computer together,fully displays the sofeware the function.Consists of DDS module, DAC module, square wave signal and triangular wave signal production module, special plastic adjustment circuit, and control software, a design of calibration signal generator circuit for oscilloscope calibrator was presented. Generated by the DDS and DAC, broadband sine-wave signal and high precision DC signal were used as the input to square wave signal and triangular wave signal production module. The circuit module is small, stable, accurate and easily taken. The paper shows the circuit diagram of the hardware module, the design process and the specific design of software programs. Finally, the results of module testing and analysis of existing problems are given.