External Mixed-signal Logic Analyzer Module Hardware Design

As a new testing instrument, Mixed Signal Analyzer has been widely used in various fields. It possesses the analysis capabilities both in data domain as the logic analyzer and in time domain as the Digital Storage Oscilloscope. External testing instruments based on USB gradually become the mainstream of virtual instrument system due to low cost, portable and easy expansion features.External Mixed Signal Analyzer consists of logic analysis module and oscilloscope module; the former will be introuduced in detail. The whole design of the logic analysis module, how to improve the sampling rate, achieve large-capacity storage and mix-trigger with oscilloscope module are mainly introduced in this dissertation. The innovation of this dissertation are: the acquisition of the analog signal and logic signal based on the same master clock ,which ensures the relevance of the data collection; The interface of waveform display also adopt the same time base,which ensures the analog waveform and logic waveform with the same time benchmark; The trigger signal produced by the mixed trigger circuit synchronous trigger the two acquisition modules, which ensure the display coherence of analog waveform and logic waveform (to the trigger point); adopting string and conversion technologies to achieve high-speed sampling.The main attributions of this dissertation include:1. The design of the sampling channel, including the design of the logic probe, the digital process of the input signal, the threshold level generator, as well as the design of analog and digital signal multiplexing circuit, which realized the pre-signal sampling and process in the digital signal sampling module, and also preserved one analog input signal to the analog signal sampling module.2. Data acquisition and control module realized in FPGA, which includes the design of the time generator circuits, the data sampling, mix-trigger and distinguish circuits and data storage.3. Design and realization of the USB interface circuit, main performance of USB protocol, the USB interface chip and the connection between data acquisition circuit and the design of the firmware are introduced.4. The hardware debugging and the design amelioration.These test results indicate that this module has good capability of logic analysis and nice data transmission with USB interface. So it can meet the requirement of high-speed signal analysis.