AllenD
Member level 5
Hi
I am trying to tapeout a mixed signal circuit using TSMC 65nm pdk. I need to input/output analog signals, sampled (analog) signals, DC signals, clock signals. The operating freq is in the proximity of 1GHz. Can I ask a few questions, please?
1. Can I just use analog I/Os for all the signals listed above, including clock signals? My reasoning is that the digital I/O is relatively slow and there is no need for me to transform my signal from 1.2V to 3.3V. On the other hand, there is no harm to use analog I/O for clock signal output.
2.There are 2 types of analog power cells to provide VDD from TSMC I/O lib. the power bus names are TAVDD and TACVDD. TAVDD is for analog domain supplied by the I/O voltage, whereas TACVDD is for analog domain supplied by the core voltage. To my understanding, these should be the supply voltage of the I/O. But that are the difference?
3. The analog signal I/O demand a secondary ESD device. I am thinking of a simple resistor and 2 diode connected mosfets. Is there a rule of thumb for the sizing of resistor or w,l of the mosfets?
Thanks
Allen
I am trying to tapeout a mixed signal circuit using TSMC 65nm pdk. I need to input/output analog signals, sampled (analog) signals, DC signals, clock signals. The operating freq is in the proximity of 1GHz. Can I ask a few questions, please?
1. Can I just use analog I/Os for all the signals listed above, including clock signals? My reasoning is that the digital I/O is relatively slow and there is no need for me to transform my signal from 1.2V to 3.3V. On the other hand, there is no harm to use analog I/O for clock signal output.
2.There are 2 types of analog power cells to provide VDD from TSMC I/O lib. the power bus names are TAVDD and TACVDD. TAVDD is for analog domain supplied by the I/O voltage, whereas TACVDD is for analog domain supplied by the core voltage. To my understanding, these should be the supply voltage of the I/O. But that are the difference?
3. The analog signal I/O demand a secondary ESD device. I am thinking of a simple resistor and 2 diode connected mosfets. Is there a rule of thumb for the sizing of resistor or w,l of the mosfets?
Thanks
Allen