On 3/14/2015 2:13 PM, Jim Thompson wrote:
On Sat, 14 Mar 2015 13:36:39 -0400, Phil Hobbs
wrote:

On 3/14/2015 1:07 PM, Jim Thompson wrote:
Oscillator Proposal...

Suppose I have a series RLC, one end grounded, the other end driven by
a chip, how might I make that into an oscillator?

All wild ideas accepted... this is for a custom chip.

...Jim Thompson


Series RLC is harder than parallel, because to leading order there's no
signal on the pin at resonance. (If it were parallel, you could do a
single-ended version of the MC1648, which you may have heard of.)

Gee! That part number sure sounds familiar ;-)


You need to arrange a negative resistance at the pin, which isn't hard
to do, and use the AC current to drive the next stage.

Cheers

Phil Hobbs

I was fretting over not wanting a DC path to ground, but maybe that
can be minimized.

...Jim Thompson


Well, if it's series, you can bias the pin anyplace you like. All sorts
of RF parts do that, e.g. the AD9956 DDS/PLL chip, which I'm working
with at the moment. I had to dig out the demo board schematic to figure
out how to drive all the differential inputs...the datasheet is a vast
wasteland.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
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