Simple waveform digitizer
The digital electronic oscilloscope is a tabletop instrument with complete performance. It has strong visibility, interactivity, signal integrity, measurement functions are defined by hardware, good user interface, and the highest real-time bandwidth. It is suitable for the development, evaluation, measurement, and Troubleshooting applications.
However, in the product line of electronic components and equipment, it is often necessary to increase the measurement speed and obtain all data of electrical indicators in the shortest measurement time to ensure that products are put on the market in a timely manner. In this case, the waveform digitizer came into being. In essence, the waveform digitizer is a simplified version of the digital electronic oscilloscope. The waveform digitizer only retains the ADC front-end and data storage/operator, omitting the back-end DAC and LCD display. In other words, retaining high speed, discarding low speed, and simplifying the complexities make the waveform digitizer more suitable for automatic test system applications.
The circuit structure of the waveform digitizer
The circuit block diagram of the waveform digitizer is shown in Figure 1. It can be seen that the waveform digitizer as a module focuses on digitizing the input analog signal. The circuit structure is very simple. The front end is an ADC chip, followed by a digital memory and an on-board digital signal processor to perform arithmetic operations and waveform analysis on the signal, and finally transmit it via a high-speed bus. to the data acquisition controller of the automated test system. Compared with digital electronic oscilloscopes, since the waveform digitizer only retains the high-speed front-end ADC circuit, it directly uses the PC's high-speed peripheral bus to transmit digital data, such as PCI and PCI Express buses, which are more efficient than general-purpose buses for instruments such as GPIB, VXI, and LXI. Higher transfer speed. In addition, the on-board digital signal processor of the waveform digitizer analyzes and processes the analog/digital converted data in real time, and then transfers it to the PC of the data acquisition subsystem for background calculations.
Analog instruments do not have physical panels and displays, only virtual panels. Therefore, the working status of the circuits at all levels of the waveform digitizer are instructed through the graphical interface, including the front-end input signal conditioning and signal acquisition methods. The input signal is converted into a data stream through the ADC. That is, operations are performed by memory temporary storage and digital signal processing. The memory performs continuous digital acquisition of the data stream and stores a large number of waveforms, while the digital signal processor performs mathematical operations and parameter analysis on the waveforms. The obtained results are sent to the background computer of the automatic test equipment subsystem through the high-speed peripheral bus for measurement result processing. It can be seen that the waveform digitizer is a software-defined measuring instrument. The software plays a key role in providing measurement engineering technicians with multiple signal inputs, large amounts of data processing, short measurement time, small occupation area, easy maintenance, and low measurement cost. platform.
