# Presentation: 504264

## Induced Gate Noise in Charge Detection

***Instrumentation Division****, Brookhaven National Laboratory, Upton, NY*

***Induced Gate Noise in Charge Detection***

## Charge  detection - capacitive signal source:

- Drain current noise:

***Induced gate noise:***

*With a capacitive signal source* *induced noise voltage spectrum* is white → both drain and gate noise can be referenced to the gate as an equivalent series noise resistance.  Neglecting correlation :

- For power optimized CMOS:   ***C******gs******≤(1⁄4)C******in****** , ***and the increase in ***R******eq*** is < 2.5%.
- The effect of correlation is less than ~10%.

***Charge  detection - capacitive signal source:***

- (Ref. 3)

## Real  Term in the Gate Admittance

***Real  Term in the Gate Admittance***

*unity gain frequency            electron transit time*

## Real (“Damping”) Term in the Control Electrode Admittance of all 

***Real (“Damping”) Term in the Control Electrode Admittance of all ***
***Charge   Controlled Devices***

- Charge in transport:

- Transconductance:

- Unity gain frequency:

- Control electrode ***admittance***:

- At high frequencies:

- Damping of tuned circuits by control electrodes with ***zero*** ***dc current*** observed in 1930’s (Ref. 1)

*transit time*

*phase shift*

*phase shift*

- a«1  ;

## Gate Induced Noise vs  f  and  fT

***f******T***(GHz)     ***g******m***(mS)       ***C******gs***(fF)
-        4               10              330
-        8               14              220
-      16               18              140
-      26               23                90
-      45               28                68

***Long L         Short L ***
********* ******≈****** ******4/3               *****(*****<3?)******************≈****** 2/3                 <1.2***

- Data from: C.-H. Chen,et al., IEEE
- Trans. Electron devices,**48**, 2884(Dec. 2001)

- Gate Induced Noise vs  ***f  ***and***  f******T***

- NF=1dB
-   0.25dB

## No significant enhancement at   L=0.18 m !

**       ****Drain current thermal noise vs V****DS****                                Gate current noise vs V****DS**

- From: A. J. Scholten et al., IEEE Trans.
- Electron Devices, **50**, 618 (March 2003)

***Noise Enhancement with V******DS****** in DSM MOSFETS?***

***No significant enhancement at   L=0.18 ************m !***

## 2/3≤  < 1.1

***“******White noise gamma factor”  vs  V******DS******  and  L***

- Gradual channel      Velocity saturation
-          region                      region

**2/3********≤************** **** < 1.1**

- From: C.-H. Chen and M. J. Deen, IEEE Trans. Electron Devices, **49, **1484(Aug. 2002)

*Noise model: Channel *
*Length Modulation (CLM)*

## «1

***Equivalent Series Noise Resistance for Charge Detection (Capacitive Source)***

***Intrinsic*** channel noise

- Gate induced

- Gate resistance

- Substrate resistance

- Induced into gate (shielded by the inversion layer!?)

- Transconductance=

- Ref.: 9

**«1**

## 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