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Active inductor for high speed operation (> 12GHz) in 16nm finfet process (Read 6344 times)
Larry_80
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Active inductor for high speed operation (> 12GHz) in 16nm finfet process
Jun 01st, 2015, 6:33pm
 
Hi,
I am just wondering if anyone can comment on challenges faced in making a relatively high quality active inductor in the 16nm finfet process node? From what i heard it is tough to make considering large area and the variation associated with the design. Please kindly comment on challenges you have encountered and how you have been able to overcome them.
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loose-electron
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Re: Active inductor for high speed operation (> 12GHz) in 16nm finfet process
Reply #1 - Jun 15th, 2015, 1:02pm
 
please explain the concept of an "active" inductor

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Jerry Twomey
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wave
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Re: Active inductor for high speed operation (> 12GHz) in 16nm finfet process
Reply #2 - Jun 15th, 2015, 3:12pm
 
loose-electron wrote on Jun 15th, 2015, 1:02pm:
please explain the concept of an "active" inductor



LE - think of the local Feedback in a Source Follower (or Emitter Follower).  You need to include Cgs and resistance before the gate.
When Cgs shorts out, and R_G > (1/gm), you have larger Z at higher frequency.

Often a single stage amp, or more likely here, a differential CML has resistor plus active inductor loads for higher frequency gain.

Wave
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loose-electron
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Re: Active inductor for high speed operation (> 12GHz) in 16nm finfet process
Reply #3 - Jun 17th, 2015, 1:53pm
 
mathematical equivalence or active circuit that performs like an inductor - ok that make sense thanks for the Smiley feedback
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Jerry Twomey
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bharat
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Re: Active inductor for high speed operation (> 12GHz) in 16nm finfet process
Reply #4 - Aug 1st, 2015, 9:12am
 
Larry_80 wrote on Jun 1st, 2015, 6:33pm:
Hi,
I am just wondering if anyone can comment on challenges faced in making a relatively high quality active inductor in the 16nm finfet process node? From what i heard it is tough to make considering large area and the variation associated with the design. Please kindly comment on challenges you have encountered and how you have been able to overcome them.


LE -- it is Gyrator ( RC LPF at the input is seen as HPF).

Larry_80 --
Pros:
1. Better than Resistance. The source degeneration with resistive load is 2 pole one zero system. Replacing resistive load with active inductor makes it 3 poles and 2 zeros system. This improves peaking and adds linearity to overall gain function.

Cons:  
1. Noise of active inductor is higher ( noise folding) and may go beyond overall rms noise spec
2.  Unlike simple resistance, maintaining the common mode is challenging but use of replica bias might help.


Thanks
-Bharat
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loose-electron
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Re: Active inductor for high speed operation (> 12GHz) in 16nm finfet process
Reply #5 - Aug 18th, 2015, 1:01am
 
Do some research on gmC filters and transconductor circuits.
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Jerry Twomey
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