I am curious what the relationship is between the drain bias current and the transconductance of a MOSFET? For instance, say you set V_DS but you double the drain bias current, how would this affect the transconductance? Does it scale based on only 'tuning' the drain bias current?
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\$\begingroup\$ Why don't you use the transconductance equation of a MOSFET and see what all parameters it is dependent upon \$\endgroup\$– saiCommented Nov 1, 2023 at 7:22
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\$\begingroup\$ well I have, and my understanding based off that is that say, a doubling in ID, would cause a double in gm (given that the other parameters remain the same) \$\endgroup\$– gooseggs2976Commented Nov 1, 2023 at 7:37
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\$\begingroup\$ What would you do with the VGS? You cannot independently double the drain current without changing the MOSFET dimensions or VGS or may be a combination of both. Checkout the MOSFET current equation in saturation. \$\endgroup\$– saiCommented Nov 1, 2023 at 11:05
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\$\begingroup\$ yea so I've thought about it... looks like gm is directly proportional to the square of Id, so by doubling Id you'd actually increase gm by a factor of sqrt(2). \$\endgroup\$– gooseggs2976Commented Nov 2, 2023 at 5:38
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As discussed in the comments, if you do not change the dimensions of the MOSFET, VGS-VTH will increase by sqrt(2) when doubling the ID (inference from the MOSFET current equation in saturation). GM will increase by sqrt(2) like you pointed (inference from the GM equation in saturation).
