1. 18/10/20151 Calibration of Input-Matching and its Center Frequency for an Inductively Degenerated Low Noise Amplifier Laboratory of Electronics and Information Technologies National school of Engineers Sfax University of Sfax Sami Mahersi, Hassene Mnif and Mourad Loulou ICECS 2010, IEEE International Conference on Electronics Circuits and Systems Athens, 12-15 December 2010

2. 18/10/20152 Outline  Introduction  Technique of input matching and center frequency calibration of an Inductively degenerated LNA Theoretical study 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. 18/10/20153 Introduction(1) Several factors causes RF front-End (LNA) performance degradation: Parasitic Effects Process variation Power Supply voltage variation Degrading the circuit performances Non performant Circuit behaviour On-chip Capacitive coupling Temperature Variation

4. Introduction(2) Input ADC Digital calibration Algorithm Sensor Tunable LNA (Device Under Test) Output Sensor DAC Basic schema of a DUT performances Self calibration system 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  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. 418/10/2015

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 18/10/20155

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

7. 18/10/20157 Schematic of LNA for calibration R L =50Ω V DD V out Ls Lg M1M1 M2M2 LdLd CdCd Rs= 50Ω Vs Zin Cg Cs Cc 1 Cc 2 R2R2 R1R1 Zout M3M3 Zin fcfc 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)

8. 18/10/20158 Where : Symbolic analysis of Input impedance and resonance frequency

9. 18/10/20159 Variation of resonance frequency versus the capacitors C tot and C s The central frequency is more dependant on the Ctot (Cg) variation However it doesn’t vary when Cs varies

10. 18/10/201510 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. 18/10/201511  Technique of input matching and its center frequency calibration for an Inductively degenerated LNA Calibration of Input matching

12. 18/10/201512 Initial performances of LNA at 2.45GHz ParameterValue S21 (dB)20.5 S11 (dB)-58.6 Real(Zin) (Ω)50.09 Imag(Zin) (Ω)-0.07 S22 (dB)-47.6 Real(Zout) (Ω)49.6 Imag(Zout) (Ω)0.09 NF (dB)1.98 CP1 (dBm)-23.6

13. 18/10/201513 Calibration of Input matching Cs is swept around 1500fF (nominal value ) : [10fF – 3000fF]

14. 18/10/201514 Impact of input matching calibration on the other LNA performances at 2.45GHz ParameterVariation range S21 (dB)[20.21, 20.74] Im(Zin) (Ω)[-0.19, -0.03] S22 (dB)[-53.14, -43.08] Re (Zout) (Ω)[49.3, 49.83] Im (Zout) (Ω)[0.049, 0.138] NF (dB)[1.98, 1.99] CP1 (dBm)[-23.3, -23.87]  Low variation of LNA gain, Noise Figure and linearity when calibrating the input impedance

15. 18/10/201515  Technique of input matching and its center frequency calibration for an Inductively degenerated LNA Calibration of input match center frequency

16. 18/10/201516 Calibration of input match center frequency  Center frequency tuning band = 214MHz It is clear that when tuning center frequency there is no impact on input matching Cg is swept in the range [267fF – 375fF]

17. 18/10/201517 ParameterVariation range S21 (dB)[20, 20.5] S22 (dB)[-48.42, -31.29] Real(Zout) (Ω)[47.77, 50.14] Imag(Zout) (Ω)[-2.16, 1.45] NF (dB)[1.77, 2.41] CP1 (dBm)[-23.15, -23.62] 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. 18/10/201518 Conclusion and future works A technique is proposed for calibrating the input matching and central frequency for an Inductively Degenerated Low Noise Amplifier operating at 2.45GHz. We studied the impact of each perfomance calibration on the others performances 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)

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