DCO频率出精度求助！

Khalil123456789

小弟最近在做DCO，在频率精度有一些问题想请教一下各位前辈。就是我的DCO的频率是由振荡器内3位开关电容和外部8位DAC输出电压共同控制的。比如说我的开关电容取111，DAC从00000000-11111111变化时会有一个频率范围。现在我想求这个DCO频率精度，是把电容控制位固定，看DAC变化一个LSB吗？我这个方法是否正确？还是另有别的方法？求助各位前辈！

smn1380

You are in wrong thread. Ask in Analog groups.
https://bbs.eetop.cn/forum-76-1.html

MustafaSami

hello, I stumbled upon you question and here's my answer:
What is the DCO implementation? is it LC-based or Ring-Oscillator based?

However, you should check the frequency step across both the DAC and the cap control.
since the DAC is 8 bits so you have 256 words to simulate
since the cap control is 3 bits, you have 8 words to simulate

So the total number of simulations for (typical corner, room temp) will be 2048. You should assess the operation using that.

Assessing the operation is to check the frequency range, the curves overlap (across the cap control), and the step per lsb of DAC word

However, when checking linearity (DNL, INL) of the DAC, you only need to fix the cap control to one word (say 101) and sweep the dac word 0, 1, 2, 3, 4, 7, 8, 15, 16, 31, 32, 63, 64, 127, 128, 255

Feel free to ask about anything related to ADPLL