The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> RTC oscillation failed
https://designers-guide.org/forum/YaBB.pl?num=1283916161

Message started by trashbox on Sep 7^th, 2010, 8:22pm

Title: RTC oscillation failed
Post by trashbox on Sep 7^th, 2010, 8:22pm

Hi all,

The RTC circuit is attached and the measurement result shows 50% chip oscillation is failed: probing the PAD on failed chip can make it oscillate successfully.

The post/pre AC simulation shows the gain is about 24dB and the TRAN can also oscillate successfully without considering packaging(BGA) and I/O issues.

Is there any suggestion? Thanks!

Title: Re: RTC oscillation failed
Post by pancho_hideboo on Sep 8^th, 2010, 2:07am

Evaluate negative impedance of oscillator and compare it with effective resistance of crystal.

See http://www.yoketant.com.tw/yoketant/terms.htm