|
Examples
of Typical Analog Circuit Design Engagements
This section
describes some typical projects that we have been involved
with in the past. The examples include the background, what
was done to assist the project and the results.
Examples
of Projects
Design
Reveiw and Analysis of a Hot Insertion
Circuit
Situation
Client was
Designing a Hot Board Insertion circuit and was concerned
about the ability of the Power Supply to sustain the
"current spike" presented by this new circuit design. They
lacked the engineering capacity to create the appropriate
Spice Simulation models and verify them in the actual
system.
Tasks
Performed
Created a model for the hot insertion portion of the
circuit that included a MOS FET, and its associated
components. Ran simulations. Ran tests in the Lab to verify
how well the models performed in relation to the actual
circuitry. Updated the model until it validated what was
measured in the system.
Results
Client was able to be assured that the new design would
function adequately in mass production without manufacturing
test and field failures.
Analog
Design Interface for High Speed PCB
Situation
Client needed someone to follow the layout of a high
speed PCB design to assure that the High Speed signals would
allow the various ICs to communicate with each other both
between and internal to the boards.
Tasks
Performed
Worked with the client to identify the critical signals
on the schematics. Assistance was given to select the
appropriate PC Board material. Layout rules were generated
for the layout person to follow. Interfaced with the layout
person to answer questions during layout, and to check on
progress.
Performed checks of
critical lines after layout was complete to assure that
layout rules were followed correctly.
After board was
fabricated, tests were run to assure the critical lines had
the correct impedance. Measurements were made on the
Assembled board to assure that signal integrity was
maintained.
Results
There were very few problems areas related to layout on
the board when circuit functionality was tested. This
prevented the need for a massive relayout that would have
seriously extended the schedule.
Design
of a High Performance, Low Noise Amplifier
Circuit
Situation
Client had insufficient knowledge of analog electronics
to create a special amplifier for very low level, wide
bandwidth signals for a high performance photodiode
amplifier to feed a high speed analog to digital
converter.
Tasks
Performed
Worked with the client to identify the specifications
required for the new circuit. Created a model and block
diagram for the circuit architecture and did initial
simulations for estimated requirements.
Searched through
available operational amplifiers and their characteristics
to come up with suitable candidates for the design. Captured
the schematic. Indicated critical signal lines on the
schematic for layout person. Created a formal Spice model of
the circuit and simulated it before it was fabricated.
Reviewed layout before fabrication. Tested the circuit after
the PCB was fabbed and assembled. Included validation of
Spice Model simulation.
Results
Created a design that met the circuit specifications and
that permitted the design to be available in rapid
time.
Design
of a Special Purpose Driver Circuit
Situation
Client was doing a redesign of an existing PCB design to
expand the capabilities of a circuit, and at the same time
shrink its size. They wanted the circuit to be simple, and
not to utilize a microcontroller. This would keep
development costs low. The circuit was to take in a standard
interface, and drive a number of digital outputs using a
standard Windows program as a driver.
Tasks
Performed
Created a specification and a plan to develop the PCB.
This included a block diagram and an initial selection of
critical components. Captured the schematic of the circuit.
Interfaced with the layout person to get PCB layed out
properly, then checked results before fab. Interfaced with
Fab and assembly houses to make model PCBs.
Tested PCBs and made
them functional. Documented the entire design, and worked
with client to make it ready for production. Held the
necessary Design and Status Reviews throughout the
project.
Results
A PCB that met all of the circuit specifications, and
that permitted the client to test a new approach to the
system design in record time. The design was largely ready
for production, once proof of concept was
assured.
Design
of a Low Power, Battery Operated Analog
Circuit
Situation
Client was creating a proof of concept model for a mixed
signal, battery powered very low power circuit. The circuit
received information via a photocell, that was encoded in
the video of a TV Raster.
Tasks
Performed
Created a specification and a plan to develop the
circuit. This included a block diagram and selection of low
power circuit techniques and components. Designed and
captured the schematic of the circuit. Interfaced with
layout person to create a PCB model of the circuit. Led and
interfaced on the Fab and assembly of the circuit
board.
Tested PCBs and made
them functional. Documented the entire design, and worked
with client to make it ready for incorporation into the
mixed signal ASIC. Held the necessary Design and Status
Reviews throughout the project.
Results
A circuit was created that met all of the circuit
specifications, and that permitted the client to test o the
system design in record time. The final design was
successfully incorporated into the ASIC, once proof of
concept was shown.
|
