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Induced Gate Noise in Charge Detection. Veljko Radeka, Sergio Rescia, Gianluigi De Geronimo Instrumentation Division , Brookhaven National Laboratory, Upton, NY. Charge detection - capacitive signal source:. Drain current noise:. Induced gate noise:.
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Induced Gate Noise in Charge Detection Veljko Radeka, Sergio Rescia, Gianluigi De Geronimo Instrumentation Division, Brookhaven National Laboratory, Upton, NY
Charge detection - capacitive signal source: Drain current noise: Induced gate noise: With a capacitive signal sourceinduced noise voltage spectrum is white → both drain and gate noise can be referenced to the gate as an equivalent series noise resistance. Neglecting correlation : (Ref. 3) For power optimized CMOS: Cgs≤(1⁄4)Cin , and the increase in Req is < 2.5%. The effect of correlation is less than ~10%.
Real Term in the Gate Admittance unity gain frequency electron transit time
Real (“Damping”) Term in the Control Electrode Admittance of all Charge Controlled Devices transit time Charge in transport: Transconductance: Unity gain frequency: Control electrode admittance: At high frequencies: phase shift a«1 ; phase shift Damping of tuned circuits by control electrodes with zerodc current observed in 1930’s (Ref. 1)
Gate Induced Noise vs f and fT fT(GHz) gm(mS) Cgs(fF) 4 10 330 8 14 220 16 18 140 26 23 90 45 28 68 NF=1dB 0.25dB Long L Short L d≈ 4/3 (<3?)g≈ 2/3 <1.2 Data from: C.-H. Chen,et al., IEEE Trans. Electron devices,48, 2884(Dec. 2001)
Noise Enhancement with VDS in DSM MOSFETS? Drain current thermal noise vs VDS Gate current noise vs VDS No significant enhancement at L=0.18 mm ! From: A. J. Scholten et al., IEEE Trans. Electron Devices, 50, 618 (March 2003)
“White noise gamma factor” vs VDS and L 2/3≤g < 1.1 Gradual channel Velocity saturation region region From: C.-H. Chen and M. J. Deen, IEEE Trans. Electron Devices, 49, 1484(Aug. 2002) Noise model: Channel Length Modulation (CLM)
Equivalent Series Noise Resistance for Charge Detection (Capacitive Source) Transconductance= Gate induced Induced into gate (shielded by the inversion layer!?) Gate resistance Substrate resistance «1 Intrinsic channel noise Ref.: 9
Acknowledgements Numerous discussions with Anand Kandasamy, Paul O’Connor and Pavel Rehak are gratefully acknowledged.
References 1. Ferris, W. R., Proc. IRE, 24, No. 1 (1936) 82 2. Van der Ziel, A., Proc. IEEE, 51 (1963) 461 3. Radeka, V., IEEE Trans. Nucl. Sci., NS-11 (1964) 358 4. Manku, T., IEEE Journal of Solid-State Circuits, 34, No. 3 (1999) 277 5 Signoracci, L., et al., Solid-State Electronics, 45 (2001) 205 6. C.-H. Chen, et al., IEEE Trans. Electron Devices, 48, (Dec. 2001) 2884 7. C.-H. Chen and M.J. Deen, IEEE Trans. Electron Devices, 49, (Aug. 2002) 1484 8. A. J. Scholten, et al., IEEE Trans. Electron Devices, 50, (March 2003) 618 9. S. V. Kishore, et al., IEEE 1999 Custom Integrated Circuits Conference, p.365