Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronic Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

Generate second LO from main LO

Status
Not open for further replies.

Ghost Tweaker

Full Member level 1
Joined
Nov 11, 2003
Messages
95
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
992
Hi everyone,

I have a pretty basic question. I'm designing a wireless receiver (discrete design on a PCB) and have at disposal a first local oscillator frequency in the 1-2GHz range, generated by a VCO. Now I need a second local oscillator freqency in the 50-100MHz. Do you guys have any recommendation on how to generate this? Currently I would use a divide by N component but these usually generate an awfull square signal and the N value is usually limited to a very narrow set of values...

Do you guys have any other methos to proceed?

Thanx in advance
 

biff44

Advanced Member level 5
Joined
Dec 24, 2004
Messages
4,837
Helped
1,354
Reputation
2,704
Reaction score
1,031
Trophy points
1,393
Location
New England, USA
Activity points
36,528
1) you can multiply the clock frequency up to be the 2nd lo
2) you can have a 2nd pll at 50 MHz
3) can take you digital clock frequency, bandpass filter it to get one of the odd harmonics, bandpass filter it, amplify it, and there you are with a sine wave
4) You can use an identical 1st and 2nd lo, although your 1st IF will be around 1 Ghz instead of 50 MHz
5) You can just use the 50 MHz IF and oversample it with an adc aliasing the frequency
6) you can just use the 50 MHz IF and do your demodulation there
7) you can injection lock or phase lock a 50 MHz VCO onto the divided down 50 MHz signal
8) you can just filter the heck out of the 50 MHz signal. All you would need to do is perhaps a 7 pole lowpass filter, and the cuttoff frequency would not be too sensitive.
9) you could run the divided down 50 MHz thru a loosely coupled regenerative amplifier tuned to 50 MHz and strip off the harmonics.
 

Ghost Tweaker

Full Member level 1
Joined
Nov 11, 2003
Messages
95
Helped
2
Reputation
4
Reaction score
2
Trophy points
1,288
Activity points
992
Thank you this is what we call beeing complete! I think I will use either a second VCO either a divide by N and filter the square signal...
 

davicente

Junior Member level 3
Joined
Jul 31, 2002
Messages
31
Helped
1
Reputation
2
Reaction score
0
Trophy points
1,286
Activity points
233
AS i can remember, you could use two different mixers with just one vco:

-a second armonic mixer
-the usual mixer

Added after 4 minutes:

AS i can remember, you could use two different mixers with just one vco:

-a second armonic mixer
-the usual mixer

Added after 4 minutes:

AS i can remember, you could use two different mixers with just one vco:

-a second armonic mixer
-the usual mixer
 

Status
Not open for further replies.
Toggle Sidebar

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top