Hi All,

I am working on a Digital Compensated Crystal Oscillator design for real time 32.768kHz clock (part of the whole project). Now there are two options in terms of architecture:
1) temperature sensor+EEPROM+analog option(change tunable xtal load capacitor bank) to change oscillation frequency
2) temperature sensor+EEPROM+digital option( keep the xtal load capacitor unchanged, but digitally change the time counter to add or remove pulse to speed up or slow down the clock counter)
The problem in 1) is we need big area to put the tunable load capacitor on-chip, however we are area limited (if we have enough area, the frequency compensation precision can be high enough);
The problem in 2) is we are not sure if it works well, especially let's say the counter precision up to +/-3ppm.
I am hoping there are some DTCXO/TCXO expert at here can give some comments.  

Thanks,

Lunren

Hi Yawei,

Target is +/-3ppm. I need a 1Hz for real time clock gen. Any suggestion or experience on this?

Thanks,

Lunren

Not expert.

Just two cents:

there are some existing products out there in the market. Many companies give lots of information in their datasheet. that tells you which approach is more popular, although may not fit into your application exactly.