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How Bad are Swiss Cheese Planes?

Holey Swiss cheese offers a popular metaphor for describing planes with a high density of clearance holes, usually under a BGA escape. The concern of many designers is the impact on the inductance in the power and ground planes due to all those holes. Since the gaps between them is narrow, won’t they constrict the current, dramatically increasing the series resistance and the loop inductance of the planes?


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Figure 7

Sources and Compensation of Skew in Single-Ended and Differential Interconnects

VNA measurements showed that the board-to-board skew distribution of realistic board topologies/routes can be broad, and the peak measured skew was quite significant. Post processing of TDR data suggested that long routes parallel to the board edge may be particularly susceptible to skew variation due to the glass weave.
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RF Module

Ten Tips for Best Board Design Practices for IoT Applications

This design guide focuses on small form factor and low power IoT products. Even though these sorts of products are not in the same performance class as server motherboards, not paying attention to signal and power integrity design principles at the beginning of the design cycle may require multiple board spins to get your IoT product working.


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BER- and COM-Way of Channel-Compliance Evaluation: What are the Sources of Differences?

We analyze the computational procedure specified for Channel Operation Margin (COM) and compare it to traditional statistical eye/BER analysis. There are a number of differences between the two approaches, ranging from how they perform channel characterization, to how they consider Tx and Rx noise and apply termination, to the differences between numerical procedures employed to convert given jitter and crosstalk responses into the vertical distribution characterizing eye diagrams and BER. We show that depending on the channel COM may potentially overestimate the effect of crosstalk and, depending on a number of factors, over- or underestimate the effect of transmit jitter, especially when the channel operates at the rate limits. We propose a modification to the COM procedure that eliminates these problems without considerable work increase.


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