The Design Of A Small Multi-function Charge Calibrator

DDS technology is the frequency synthesis technology that has been developed in recent years. It has many advantages such as fast frequency conversion, high frequency resolution, low phase noise, continuous phase frequency, and directing phase modulation, frequency modulation in the digital domain, so it has been widely applied in the signal and communication systems and etc. Direct digital frequency synthesis is the basic principle of charge calibrator,MSP430 MCU control the external circuit in order to achieve the outputting of the signal. With the help of LCD, the system output the voltage and charge signals, whose wave form, frequency, amplitude, baseline can be arbitrarily adjustable by the interrupt keys.The voltage signal can be used as a common signal source or a calibration about piezoresistive sensor system. The charge signal is used to calibrate the system using piezoelectric sensors.Based on the marketsurveys and the present situation of study, this paper mainly discusses the principle and hardware design of a small multi-function charge calibrator. The article in accordance with instrument development progress is divided into the following sections. Firstly, analyze the frequency synthesis theory and highlight the spectral characteristics of DDS technology. On these basis, it will put forward an overall program of the charge calibrator; Secondly, it will give a specific description about various aspects of system implementation, including hardware circuitry, software compilation, as well as the mechanical installation structure. Three parts together will make the design truly become a complete instrument; Finally, test system performance and analyze the results. The results show that the charge calibrator program is correct, feasible, and the performance of the instrument hit a target which is required by subjects.