LT1037 Ultrapure 1khz sine wave generator

Hi Happppy:  Is the output a sinusoid, or is the output clipping against the supply rails?

If the output is sinusoidal, then the frequency is set by the Wien bridge.  A drift in the frequency must be due to a drift in either the resistance or the capacitance.

Hi, Happppy

Let's try to understand this. Frequency is decreasing, what is the reason?

Lets look at image:

Equation of frequency have R and C parameters in denominator. If it's increasing, frequency is decreasing. 

Signal current flow through resistors and capacitors, cause heating of this elements. Check specifications of your resistors, what value of TCR.

Solving of this problem: you should wait. Warm-up period is needed. If you will analysing frequency values at time, you will see that value approaching the steady-state value

Regards,

Kirill

The output is a sinusoid.

Yes, you're right. So, How can I solve this?

Actually in 1khz calibrator, there is no drift.

Usually, precision analog devices required warming up for a certain time. This is the simplest solving.

Ok... so why doesn't a calibrator make that result?

When I use a calibrator, the exact 1khz sine wave comes out right away. 

What calibrator are we talking about?

Please, inform us specifications of elements

I use a calibrator CAL200. http://www.larsondavis.com/products/calibrators/modelcal200 .

Hi, Happppy

I was able to find a description of how this calibrator works. This is not precision sine wave generator. The signal is generated by a highly stable crystal oscillator, therefore value of frequency is very stable after turn-on

If you want use this generator on LT1037, you should to cope with frequency drift after turn-on.

Regards,

Kirill

Here is a method of stabilizing a Wein bridge oscillator:

https://www.analog.com/en/technical-articles/injection-lock-a-wien-bridge-oscillator.html

The locking signal does not need to be "very pure", but don't tempt fate - use the best you can find. You could start with one of the popular DDS sinewave generators, like the AD9850. Do a web search on "Analog Devices DDS board", there are lots of people making low-cost modules. This will give you an accurate frequency reference that the Wein bridge oscillator will "clean up".

-Mark