RF Design - Eliminate the 'Black Magic'
by Tim Mintzer, EDC Inc.
Like any electronics development project, an
RF design can be broken down into 3 basic phases.
- Specification Phase
- Development Phase
- Production Phase
Each phase presents its unique challenges on
an RF circuit compared to other electronic circuits.
Although it is extremely useful, but not
necessary, having a person in your facility with a basic understanding
of RF will help streamline the specification phase. However, since this
is usually not the case, the consultant should be able to guide you
through this phase. By having a good understanding of the product's
functionality, a detailed specification can be generated. Remember to
include any regulatory testing required such as FCC, CE, VDE, etc.
During the specification phase, it is a good
idea to put the consultant on a small retainer to accomplish this task.
Most specifications can be formalized in much less that 10 hours and
will save hours in the long run. Too many times, companies will send
out a "half baked" spec and insist that consultants bid on the project.
Upon contract award, the consultant will realize that certain specs are
not achievable and will begin the long arduous negotiation process.
A well detailed specification will save time
and money in the long run. It can also prevent "soured" relationships
with the client and consultant.
From the detailed specification, the
consultant will begin the design phase. Realize that the specification
is the consultant's "guiding light" for the development. An RF project
will require more "up front" analysis and computations. With the many
analysis software programs available, the consultant should have these
tools available to use in this phase. Because of the "magic" nature of
RF, it is important to thoroughly analyze the proposed circuit. This
will help reduce the number of board turns to achieve the required
During the actual breadboard build and test
phase, an RF circuit will present many unforeseen challenges. These
will present themselves in the form of oscillations, gain problems,
VSWR problems, etc. It is important for the client to understand that
these problems will require more time to solve. It is not uncommon in
an RF circuit to build the circuit, solve these problems, then change
the layout, only to find new problems. This is where experience and a
thorough analysis will help.
Sometimes RF circuits will require different
manufacturing and test methods. The client should require that these
considerations be addressed in the Statement of Work/Specification.
Most RF engineers are well versed in the unique manufacturing and test
methods required. They can guide the client setting up manufacturing
and test lines or help to select a competent Contract Assembly company.
Training is also an important consideration and should be addressed.
Although the actual phases are the same as
any other electronics development effort, RF circuits are more
challenging. Clients with a basic understanding of these various
challenges will be more effective working with a consultant. This will
lead to a better, quicker and more manufacturable design.
© 2005 - Tim Mintzer and EDC Inc. -
Reproduction without permission prohibited. All Rights Reserved