Laboratory of Electronics and Information Technologies National school of Engineers Sfax

1. ICECS 2010, IEEE International Conference on Electronics Circuits and Systems Athens, 12-15 December 2010 Calibration of Input-Matching and its Center Frequency for an Inductively Degenerated Low Noise Amplifier Sami Mahersi, Hassene Mnif and Mourad Loulou Laboratory of Electronics and Information Technologies National school of Engineers Sfax University of Sfax

2. Outline • Introduction • Technique of input matching and center frequency calibration of an Inductively degenerated LNA • Theoreticalstudy of the calibration technique • Calibration of Input matching • Calibration of center frequency • Impact of the calibration on the LNA behaviour • Conclusion and future works

3. Introduction(1) • Several factors causes RF front-End (LNA) performance degradation: On-chip Capacitive coupling Temperature Variation Power Supply voltage variation Process variation Parasitic Effects Degrading the circuit performances Non performant Circuit behaviour

4. Tunable LNA (Device Under Test) Input Output DAC Sensor Digital calibration Algorithm ADC Sensor Introduction(2) Basic schema of a DUT performances Self calibration system • Self Calibration systems are used for self controlling and self correcting the performances of a Device Under Test in order to compensate performances deviations • Principle: The sensors take the input and the output signals of the DUT. Transform the RF signals into DC voltage converted to digital for processing by the calibration algorithm block. The results, producing a correction signal which is fed back to the Tunable DUT. J. Wilson, M. Ismail, “Input match and load tank digital calibration of an inductively degenerated CMOS LNA,” Integration, the VLSI Journal, vol. 42, Issue 1, pp. 3-9, January 2009

5. In This Work A Calibration schema for a LNA performances • We propose a new technique to tuning two performances of an Inductively Degenerated low noise amplifier which are : the input matching and center frequency. • The purpose is to have separate control of both characteristics • Low impact on Amplifier other characteristics: Gain, Linearity and Noise Figure

6. Technique of input match and its center frequency calibration for an Inductively degenerated LNA • Theoretical study of the calibration technique

7. Schematic of LNA for calibration VDD • Cs capacitor for the tuning of input • matching • Cg capacitor in parallel with Ls for • the tuning of the central frequency • Advantages compared to already • proposed techniques: • Avoid the use of the inductance tuning (complexity in the implementation) • Having independant tuning of the parameters S12 and fo) Ld Cd R1 Cc2 Vout R2 M3 M2 Zout RL=50Ω fc Cc1 Cg Lg M1 Zin Rs= 50Ω Cs Ls Vs Zin

8. Symbolic analysis of Input impedance and resonance frequency Where : Where :

9. Variation of resonance frequency versus the capacitors Ctot and Cs • The central frequency is more dependant on the Ctot (Cg) variation • However it doesn’t vary when Cs varies

10. Variation of input impedance versus capacitor Cs for different values gm and Ls • Decreasing gm makes the tuning range of the input impedance more wider • Decreasing Ls makes the tuning range of the input impedance more wider.  This is to be considered when designing the LNA and a compromise can be reached when setting the values of gm and Ls

11. Technique of input matching and its center frequency calibration for an Inductively degenerated LNA • Calibration of Input matching

12. Initial performances of LNA at 2.45GHz

13. Calibration of Input matching • Cs is swept around 1500fF (nominal value ) : [10fF – 3000fF]

14. Impact of input matching calibration on the other LNA performances at 2.45GHz  Low variation of LNA gain, Noise Figure and linearity when calibrating the input impedance

15. Technique of input matching and its center frequency calibration for an Inductively degenerated LNA • Calibration of input match center frequency

16. Calibration of input match center frequency • Cg is swept in the range [267fF – 375fF] • Center frequency tuning band = 214MHz • It is clear that when tuning center frequency there is no impact on input matching

17. Impact of center frequency calibration on the other LNA performances at 2.45GHz  Gain and linearity are not affected by Noise figure varies a little but still lower than 3dB

18. Conclusion and future works • A technique is proposed for calibrating the input matching and central frequency for an Inductively Degenerated Low Noise Amplifieroperating at 2.45GHz. • We studied the impact of each perfomance calibration on the othersperformances of the LNA at 2.45GHz, good results are observed since these calibrations have no significant effect on the other characteristics of the LNA. • In the future: we will investigate on some other calibration techniques for the other LNA performances (Gain, Noise figure, linearity)

19. THANK YOU