| As a time-domain measurement instrument, oscilloscopes are widely applied. This article describes a miniature low-power USB oscilloscope, which is a virtual instrument based on USB2.0interface and supports a true sense of the hot-swappable. Domestic USB oscilloscopes are rare and most of them integrate multiple functions of the instrument, thus have great volume and energy consumption. So, it’s necessary to develop a miniature low-power USB oscilloscope for the domestic market.This dissertation describes an USB oscilloscope hardware system design, which possesses the100MSa/s sampling rate, analog bandwidth of25MHz and integrated arbitrary waveform generator. The design of analog channels, channel calibration and the access of calibration parameters are discussed in this dissertation. Besides, it offers program of USB interface circuit design, collection and storage of data, micro-and low-power, arbitrary waveform generation and control circuit design.The main contents are as follows:1. The design of the analog channels, including the design of signal conditioning channels and trigger channel. Signal conditioning channels are not only to adjust the magnitude of the input signal to the appropriate voltage acquisition range of the ADC, but also to condition the output signal to satisfy user’s requirements. In condition, it can transfer AC and DC options and provide waveform of the vertical offset.2. The design of data acquisition and storage, arbitrary waveform generation and control circuit. All of them are achieved by function modules in FPGA, which consists of following modules:the ADC control, access control, decoding circuitry, memory control, time base control, data storage, the PLL circuit control and arbitrary waveform generation.3. The access of calibration parameters. Calibration parameters, acquired by channel signal conditioning and trigger channel are stored in the EEPROM.4. The design of USB interfaces. The CY7C68013, a dedicated USB interface chip, enables the communication with a PC. 5. The design of PCB board and power supply. This USB oscilloscope is compact and portable and its power supply meets the low power requirements. All indicators and functions satisfy the design requirements. |
