how to reduce VCO frequency variation over tempareture?

Status
Not open for further replies.

lijulia

Member level 3
Joined
Jan 5, 2003
Messages
57
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
468
for eg. TI part can get as low as 10MHz from -40 to 110 degree, we only can achieve 50 - 40 MHz which is about 1v Vtune change.
 

One common way of doing it in a LC resonant circuit is to pick the C part to have a negative tempco val equal to the positive tempco val of the L to try and cancel total temp drift.
 

so, it really depends on the process, right?
 

I guess, you're not talking of a LC oscillator VCO? Would be easier to discuss when knowing the particular part.
 

I am talking about LC VCO, but c & L temp variation coefficient is really depend on the each process, right? also, the value of c & L will affect other performance (PN & tuning range) , right?
 

Hello,

for wide temperature range, as you have, you must basically try to use low TC devices. For inductance, only air coil is appropriate, no ferrite. Then a residual TC from VCO circuit could be hopefully compensated in part. But I doubt, if compensation will work for wide range. Most non-zero TC capacitors are specified for -20..+85 at maximum.

Regards,
Frank
 

Status
Not open for further replies.
Cookies are required to use this site. You must accept them to continue using the site. Learn more…