Get 800MHz Local Oscillator Input for LT5521 Upconverting Mixer

[awaiting]

Hello everyone,i am using an upconverting mixer(LT5521) which converts a 100MHz signal to 900MHz.it requires a 800MHz of local oscillator input.can anyone suggest an IC or a circuit that can be used to get the local oscillator input.

Thank you

 

[berkeman]

Hello everyone,i am using an upconverting mixer(LT5521) which converts a 100MHz signal to 900MHz.it requires a 800MHz of local oscillator input.can anyone suggest an IC or a circuit that can be used to get the local oscillator input.

Thank you

Are you familiar with MiniCircuits?

http://www.minicircuits.com/sitemap.html

.

 

[davenn]

Hello everyone,i am using an upconverting mixer(LT5521) which converts a 100MHz signal to 900MHz.it requires a 800MHz of local oscillator input.can anyone suggest an IC or a circuit that can be used to get the local oscillator input.

Thank you

you are going to have to build a Local Osc LO

as berkeman hinted, visit minicircuits, they have a wonderful range of VCO's (voltage controlled oscillators) One of those will be the heart of your LO. you will then have to decide if you want to have it free running or PLL'ed (phase locked looped) for stability
The stability you require will be dependent on what you transmitter/receiver is for, the bandwidth used wideband/narrowband, voice/data etc

cheers
Dave
VK2TDN

 

[vk6kro]

You could buy one of these:
Ebay item no 260634345068
They are 100 MHz crystal oscillators selling at $2 for two. (3 volts though.)

You could then follow it with a doubler (frequency multiplier) to 200 MHz.

Then another to 400 MHz.

Then another doubler to 800 MHz.

Unfortunately, you would need some specialised measuring equipment and experience to do this. Mainly the problem is that you need to know that the 200 MHz tuned circuit is resonant at 200 MHz and not 100 or 300 MHz. And so on for the other circuits.

There is another possibility. A company called Silicon Labs produces a chip called a Si570 which can be programmed for you at 800 MHz. It would then produce just 800 MHz output.

Their website does not seem to give prices for this service.

They have another family of devices:
Silicon Labs' Si5322, Si5325, Si5365 and Si5367 family of low jitter programmable clock multiplier ICs provides flexible integer clock multiplication.
They take inputs and multiply them by some integer value to produce a higher frequency:

Flexible integer clock multiplier from 10 to 945 MHz and select frequencies to 1.4 GHz from an input frequency of 10 to 710 MHz

So, apparently, you could take a stable oscillator on some low frequency like 100 MHz and multiply it to 800 MHz in one chip.

Maybe you could send them a query to find out what they can offer and at what price.

 

[MATLABdude]

I don't really have a whole lot of RF communications experience, but based on a quick perusal of the datasheet, are you sure that your mixer doesn't actually require 900 MHz local oscillator input as a carrier for your 100 MHz signal? My recollection is that frequencies don't add quite like that (unless my terminology is off).

 

[vk6kro]

I don't really have a whole lot of RF communications experience, but based on a quick perusal of the datasheet, are you sure that your mixer doesn't actually require 900 MHz local oscillator input as a carrier for your 100 MHz signal? My recollection is that frequencies don't add quite like that (unless my terminology is off).

No, they do add up like that.

100 MHz signal PLUS 800 MHz local oscillator gives a 900 MHz signal out.

There will also be a 700 MHz difference signal which has to be filtered out, as this is 800 MHz MINUS the 100 MHz signal.

 

[MATLABdude]

No, they do add up like that.

100 MHz signal PLUS 800 MHz local oscillator gives a 900 MHz signal out.

There will also be a 700 MHz difference signal which has to be filtered out, as this is 800 MHz MINUS the 100 MHz signal.

Ah, there I go:
http://en.wikipedia.org/wiki/Frequency_mixer#Mathematical_description

Even supposed learned folks learn new things here every day!

 

[awaiting]

i think the minicircuits site is nice source,i did get the required VCO's.

Thank you everyone for your replies!

 

[davenn]

i think the minicircuits site is nice source, i did get the required VCO's.
Thank you everyone for your replies!

Yes they are :) I use a lot of their products in various projects.
let us know how your project progresses

Dave
VK2TDN