Optimum Design Associates Blog



Embedded Microstrip Transmission Lines in RF PCB Design

Embedded Microstrip

Strictly speaking, the application of soldermask, conformal coating or other surface treatments will change a pure surface microstrip line to an ‘embedded or coated microstrip’ line. This, however, is not what is traditionally referred to as embedded microstrip line, and the determination of actual characteristic impedance is more difficult with these because of the inconsistency of dielectric constant and thickness of the material above the trace.


Microstrip Transmission Lines in RF PCB Design

Microstrip is still by far the most commonly used transmission line structure in RF and microwave designs. This is becoming less the case though, as digital and mixed technology designs continue to increase in speed and density.


RF PCB Stackups: X and Y Axis Isolation

Isolate In X/Y Axis

Because this is a mixed signal design, we need to pay careful attention to how we will isolate these different circuit types from each other. The easiest way is to do the simple X/Y axis isolation, by defining different areas of the board for different circuit types. This works well when the density, particularly in digital circuits, is low enough and the separation between circuit types is very clearly defined.


RF PCB Transmission Line Width

Typically, all connections in a digital circuit board are impedance controlled. This is by virtue of the fact that most layout designers will define, for example, 50 ohms as the default routing model for single ended connections.


Transmission Lines in RF PCB Design

Transmission Line Fundamentals

Over the last ten to twenty years, advances in IC fabrication technology have led to huge increases in both the operating frequencies and edge rates of switching signals in digital circuits. This has really pushed digital circuit design into the frequency domains that were previously considered RF and/or microwave. As a result, it has become important to consider the transmission line parameters of the connecting traces used for digital signals in circuit boards as much as they have always been considered for RF connections. 


Toward A More Rational Silkscreen

Today’s complex PCBs are being packed with a boatload of tiny components and are designed to run at ever-increasing speeds. So it certainly comes as no surprise to hear that silkscreen legends are fairly low on the designer’s priorities for consideration. However, the silkscreen’s function—that of aiding the manufacturer and engineer to locate components on the board—remains important.


Should Cost Examples For PCB Assembly

Here's a pocket guide to printed circuit board assembly (PCBA) prices in China, Mexico, and the United States. Our pocket guide gives a quick view of expected prices for PCBA's based on region, value, and number of component placements. 


Should Cost Analysis vs. Strategic Sourcing


Strategic sourcing is the process of requesting quotes and comparing prices. By competing suppliers against each other the buyer hopes to discover the best price. Does it work for contract manufacturing? The world's top OEMs don't think so.


How To Get Suppliers Costed BOMs


OEM's that employ strategic sourcing techniques often find contract manufacturers are reluctant to supply costed bill's of material. Here are 2 good reasons and 2 bad reasons for this reluctance. Understand the differences then use our 3 secrets to getting the costed BOMs.


5 Things You Should Know About NRE

Non-recurring engineering (NRE) is a broad term referring to a one-time cost to develop, design, or manufacture a new product. It can mean different things in different industries, depending on the product, process, and even supply chain strategy. In the PCB industry—especially in pull-based contract manufacturing—NRE refers to specific setup costs for manufacturing a newly introduced PCB assembly.