TDR based on vector network analyzer E5071C and traditional sampling oscilloscope TDR-EEWORLD

Collect

In recent years, with the popularity of multi-Gbps transmission, the bit rate of digital communication standards has also increased rapidly. For example, the bit rate of USB 3.0 reaches 5Gbps. The increase in bit rate has brought to light problems that have never been seen in traditional digital systems. Problems such as reflection and loss can cause digital signal distortion, resulting in bit errors. In addition, as the acceptable time margin for the correct operation of devices continues to decrease, the timing deviation problem on the signal path becomes very important. Radiated electromagnetic waves and coupling generated by stray capacitance can cause crosstalk, causing errors in device operation. As circuits become smaller and more compact, this problem becomes more and more obvious. Even worse, the reduction in power supply voltage will lead to a decrease in signal-to-noise ratio, making the operation of devices more susceptible to noise. Although these problems increase the difficulty of digital circuit design, the pressure on designers to shorten development time has not been reduced at all.

As bit rates increase, the above problems are unavoidable, but they can be detected and characterized using high-precision measurement instruments. The following are the measurement requirements that must be followed when using instruments to handle these problems:

a. A large measurement dynamic range is required over a wider frequency range

One way to achieve high dynamic range is to reduce noise. If the instrument noise is minimized, very small signals (such as crosstalk signals) can be measured. It is also critical to accurately measure high-frequency components because they are the most common cause of signal integrity problems.

b. The excitation signal must be accurately synchronized

When measuring the timing deviation of signals between multiple microstrip lines, precisely synchronized stimulus signals can better ensure accurate measurement results.

c. Rapidly perform measurements and refresh the measurement results displayed on the instrument screen. The ability to quickly perform measurements and refresh the displayed measurement results can make product design more efficient and improve production throughput.

Traditionally, time domain reflectometry (TDR) based on sampling oscilloscopes has been used for testing cables and printed circuit boards. Since such oscilloscopes have relatively large noise, it is difficult to achieve high dynamic range and fast measurement at the same time. Although the noise can be reduced by averaging, this will affect the measurement speed. The jitter between the multiple signal sources on the oscilloscope used to measure timing deviations can also cause measurement errors. In addition, it is very difficult to design electrostatic discharge (ESD) protection circuits for TDR oscilloscopes, so TDR oscilloscopes are easily damaged by ESD.

These problems are difficult to solve with a TDR oscilloscope alone and can only be solved with the E5071C-TDR, a TDR solution based on a vector network analyzer (VNA).

Reference address：TDR based on vector network analyzer E5071C and traditional sampling oscilloscope TDR

Previous article：High-speed PCB controllability and electromagnetic compatibility design
Next article：Research on the Design of Power Supply Solution for DSP Processor

Popular Resources
Popular amplifiers