Saturday, August 01, 2009

Mixed Circuits Analog with Digital

Mixed Circuits Analog with Digital

Here are some circuits that have both Analog and Digital Signals in them. At one time i wanted to make reed relays, it was a good spot to be in, as it was used in Telecommunications. Even Small Office EPABX systems would have quite a Few of them. It was Simple, get some reeds from OKI and wrap them up in some copper coil and Pot them in a plastic can with epoxy. Before i could get even some trials out, the market was flooded with Good Quality Reed Relays from many.

Fluid or Water Level with Reed Relays

So the Lesson, "Time to Market" should be minimum without sacrificing Quality. That brings us to another metric, The TTM/Q Ratio ;-) . This should not be mixed up with "Time to Exhibition or Trade Show".

Fluid or Water Level with Reed Relays

"Reed Relay. It was invented by Dr. W. B. Ellwood at Bell Labs in 1936. Contacts are in a sealed glass tube filled with inert gas like in a bulb, so they do not corrode. It is faster than regular relays and as no spring is used it has a longer mechanical life. The two contacts are ferromagnetic blades plated with rhodium. When you take a magnet close by, the contacts touch each other. You can also put the reed in a coil, then when you energize the coil the reed operates. Used in telecommunication.OKI is one manufacturer of this type of component. "

Some Circuits on above pages are..
  • Voltage to pulse converter using opamps
  • Analog Section of 8751 based flowmeter
  • Voltage to pulse converter impulse counter
  • 16 channel analog multiplexer
  • 8 channel analog mux with sample hold
  • Digital Control for 8 channel analog mux

Thursday, July 16, 2009

Mixed and Interface Circuits

Mixed and Interface Circuits : 

Most of the sensor interface and instrument inputs are analog; even if it event based like a limit switch, analog circuit protection and signal conditioning is required before it reaches the level sensitive digital circuit blocks.

Starting with Schmitt triggers and to the VCO and A-D Converters, are grades of Mixed Circuits. I feel Comparators like LM339, Timers like the 555 and Phase Locked Loop PLL are fundamental mixed circuits as they have a analog voltage detection.

DSP and uC with built in A-D or D-A or even SOC are Public ASICs and Fall in the Embedded Systems Block. Public ASICs are not user specific, they can be branded, numbered and provided with Application notes for the use of the Design Departments of any firm. User Specific ASICs are custom built and have only an application with that manufacturer for a Specific Product type. This also protects the IP of Code and Device Design. Custom ASICs are limited to the Platform and Technologies for which they were designed. Then we have programmable and configurable chips other than uC for logic like PLD, CPLD, FPGA and SOC, there is even some talk of mixed or analog configurable chips.

It would be nice if they made a breadboard chip with 12 opamps, 24 comparators, Some PLD and a couple of uC. Then we certainly need software trimmable or tweakable Resistors and Trimpots. This is the Magnum Opus of EDA. A EDA Chip Printer may be coming soon ! (Affordable by small firms).

Read More - Mixed and Interface Circuits - delabs

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