finFET Noise

Noise Aspect	FinFET vs Planar	Better or Worse?	Why (Physical Reason)
1/f (Flicker) Noise at Moderate/High Vgs	Lower	Better	Volume inversion keeps carriers away from interface → less trap interaction.
1/f Noise Variation (Device-to-Device)	Larger spread	Worse	Each fin has its own sidewall roughness, trap density, and geometry → statistical variation.
RTS (Random Telegraph Signal) Noise	More prominent in minimum fins	Worse	One trap can strongly modulate current because channel width is tiny (a few nm).
Thermal Channel Noise (γ-factor)	Slightly different; often slightly lower	Slightly Better	Improved gate control and reduced channel length modulation reduce excess thermal noise.
Gate-Induced Noise (Gatenoise / Induced Gate Noise)	Bias-dependent; correlation (α) improves slightly	Better for RF	3D geometry and better electrostatics reduce channel–gate capacitive coupling.
Shot Noise from Source/Drain Tunneling	Minimal at 14–22 nm; increases <10 nm	Worse at very small nodes	Shorter channels & high fields → more tunneling → shot-like behavior.
Subthreshold Noise	Often lower	Better	Stronger electrostatic control → reduced drain-induced barrier lowering → lower leakage/noise.
Mismatch-Induced Noise Variation	Higher	Worse	Fin width/height LER, quantized number of fins → mismatch → noise spread.
Low-Frequency Noise in Analog Bias Region (Vgs just above Vth)	Often lower but more unpredictable	Mixed	Volume inversion helps, but trap sensitivity is highest near threshold.
Channel Mobility Fluctuation Noise	Reduced influence	Better	Carriers distributed in bulk rather than entirely at interface.
Carrier Number Fluctuation Noise	Strong at low Vgs; weaker at high Vgs	Better at high Vgs	Better gate control and volume inversion reduce ΔN sensitivity.
Noise in Wide Devices	Highly dependent on number of fins	Mixed	More fins → noise averages out; few fins → noisy and inconsistent.
RTS Noise Averaging in Multi-Fin Devices	Improved	Better	Many fins statistically de-correlate RTS bursts, lowering impact.
Noise Figure in LNAs/Current Mirrors	Generally slightly improved	Better	Lower flicker + improved electrostatics → cleaner gm for same current.
High-Frequency Noise (mmWave)	Slightly better	Better	Improved gate control and reduced Cgd → better NFmin and Gmax.

• Flicker noise improves because carriers move into the fin volume, away from surface traps.

• RTS noise worsens because extremely narrow fins amplify single-trap effects.

• Thermal noise slightly improves due to better electrostatic control.

• Gate noise improves because channel–gate coupling is weaker in multi-gate geometry.

• Noise variation worsens because fin geometry variations dominate mismatch.

• Subthreshold noise improves thanks to lower DIBL and steeper subthreshold slope.

• mmWave/high-freq noise improves due to better channel charge control and reduced Cgd.

✔ Better for:

• Precision analog at moderate–high overdrive

• LNAs and RF front-ends

• Low-noise current mirrors (with multiple fins)

• gm/Id-based design (FinFETs have stronger electrostatics → better gm)

✘ Worse for:

• Very small devices with 1–2 fins

• Circuits biased near threshold

• Small-signal circuits sensitive to RTS and noise bursts

• Ultra-low-power circuits where stochastic variation dominates