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I need to build up a VCO from 250-350 MHz. I have found an interesting IC called MC12149 from Motorola. However, it seems to be archived and no longer manufactured. Looking at the datasheet, it looks very simple configuration. I have been searching here on Stack and in many stores yet I have not found a substitution for such IC.

Do you know any suitable IC?

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  • \$\begingroup\$ Old one MC100EL1648 still in the market. \$\endgroup\$ – kimstik Jan 30 at 16:26
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You can use a colpitts oscillator with simple varactor control. Here's one that claims to oscillate at 1 GHz : -

enter image description here

It has a good tuning range too (2.3:1). Just scale components to suit your mid frequency and you should be in business. Note that the VCO control voltage may be a bit excessive but this comes with the territory for this type of control.

As for supply voltage to the main circuit, it's highly likely that this design will work down to below 3V. Here's one that uses a lower control voltage but has less range so, somewhere between the two might be exactly what you are looking for: -

enter image description here

Alternatively just buy one from mini-circuits: -

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  • \$\begingroup\$ Mini Circuits is my go to supplier for VCOs , try here \$\endgroup\$ – Neil_UK Jul 15 '16 at 19:44
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    \$\begingroup\$ And does anyone know why MC12149 has disappeared? It was cheap and really easy to configurate. \$\endgroup\$ – Rubén Sánchez Jul 16 '16 at 21:12
  • \$\begingroup\$ Ask Motorola is my only advice. \$\endgroup\$ – Andy aka Jul 16 '16 at 21:14

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