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Usage of the Inductor From the Standard Library In CMOS Technology
Dear my fellow designers,
I have been curious about the Inductor in CMOS Lib for quite a while. As you know, the inductor's ground plane should be contacted to some voltage level, and in my case, it should be the voltage level of the substrate.
And furthermore, the Inductor has two ground plane options: M1 or BFMOAT, then in my case, it is BFMOAT. Therefore BFMOAT will be contacted to the substrate, and actually in the foundry training tutorials, the methodology should be as below:
As illustrated, ground plane is not connected to the substrate contact directly, but instead, to the AC ground firstly.
Here comes my questions:
1. I have put some AC ground (actually LNA_GND in my case) to the sub. contact, which means the voltage level of LNA_GND is contacted with the substrate through some equivalent resistance ( ~5K Ohms) of the sub contact. Am I supposed to make this substrate contact as small as possible (which means bigger equivalent resistance) so that not too much noise will be fed back to the substrate ?
2. The BFMOAT IND, as a non-build layer, or dummy layer, what is its function except indicating the virtual connection between ground plane of the inductor and AC ground/sub contact ? Does its width matter? How will the foundry process this dummy layer, I mean, what will foundry really exactly do to connect the ground plane to the AC ground/sub contact ?
3. Am I supposed to make the AC ground/sub contact far away (> 50um) from the BFMOAT, or not ?
Thanks so much for your time and have a good day
Dear my fellow designers,
I have been curious about the Inductor in CMOS Lib for quite a while. As you know, the inductor's ground plane should be contacted to some voltage level, and in my case, it should be the voltage level of the substrate.
And furthermore, the Inductor has two ground plane options: M1 or BFMOAT, then in my case, it is BFMOAT. Therefore BFMOAT will be contacted to the substrate, and actually in the foundry training tutorials, the methodology should be as below:
As illustrated, ground plane is not connected to the substrate contact directly, but instead, to the AC ground firstly.
Here comes my questions:
1. I have put some AC ground (actually LNA_GND in my case) to the sub. contact, which means the voltage level of LNA_GND is contacted with the substrate through some equivalent resistance ( ~5K Ohms) of the sub contact. Am I supposed to make this substrate contact as small as possible (which means bigger equivalent resistance) so that not too much noise will be fed back to the substrate ?
2. The BFMOAT IND, as a non-build layer, or dummy layer, what is its function except indicating the virtual connection between ground plane of the inductor and AC ground/sub contact ? Does its width matter? How will the foundry process this dummy layer, I mean, what will foundry really exactly do to connect the ground plane to the AC ground/sub contact ?
3. Am I supposed to make the AC ground/sub contact far away (> 50um) from the BFMOAT, or not ?
Thanks so much for your time and have a good day