This paper presents 5-6 GHz front end Low Noise

Amplifier application for IEEE standard 802.11 system for WLAN application. This amplifier uses FHX76LP Low noise SuperHEMT device designed for DBS application from Eudyna Device USA Inc.This paper is present design and simulation of single stage LNA circuits. A single stage LNA has successfully designed with 26.92 dB forward gain and 1.32 dB noise figure, which stable along the UNII frequency band

A. A. Abd Aziz

Abd Aziz, Mohamad Zoinol Abidin

M. F. Selamat

M. H. Che Halim

Othman, Abdul Rani

Sahingan @ Samingan, Md Saiful Azri

English

Universiti Teknikal Malaysia Melaka (UTeM) Repository

Proceedings of IEEE 2008 6th National Conference on Telecommunication Technologies andIEEE 2008 2nd Malaysia Conference on Photonics, 26-27 August 2008, Putrajaya, Malaysia5-6 GHz Front End Low Noise AmplifierM.H Che Halim', M. Z. A. Abd Aziz1' A. RaniOthman1 , S.A Sahingan1, M.F Selamat1 and A.AAbd AzizlFaculty of Electronic & Computer EngineeringUniversiti Teknikal Malaysia Melaka (UTeM)Locked Bag 1200, Hang Tuah Jaya,75450Ayer Keroh, Melaka,Malaysiahafizzan @ gmail.com,mohamadzoinol @utem.edu.my,rani@utem.edu.my,asreenanuar@ gmail.com,cyconx 1 @ gmail.com, faiesz84@gmail.comAbstract -This paper presents 5-6 GHz front end Low NoiseAmplifier application for IEEE standard 802.11 system for WLANapplication. This amplifier uses FHX76LP Low noise SuperHEMTdevice designed for DBS application from Eudyna Device USA Inc.This paper is present design and simulation of single stage LNAcircuits. A single stage LNA has successfully designed with 26.92 dBforward gain and 1.32 dB noise figure, which stable along the UNIIfrequency band.Keyword: Wireless LAN; Low Noise Amplifier; Gain; NoiseFigure; Matching Circuit.I. INTRODUCTIONThe IEEE 802.11 standard is used as references. TheLow Noise Amplifier (LNA) system should meet this standardrequirement and should operate properly for WLAN Bridgesystem [1]. The main requirements of the LNA are the lowestpossible noise figure (NF) with a reasonable gain. The generaltopology of the LNA consists of three stages: the input matchingnetwork (IMN), the amplifier itself and the output matchingnetwork (OMN) [2],[3],[4]. The 5.8 GHz wireless LAN marketgrows rapidly and offers various benefits to the user 5.8 GHzLAN technology supports multimedia services, real time voiceand video transfer and other bandwidth intensive applications[5].This paper presents two different designs of a LNA at5.8GHz. The circuit design starts from FHX76LP Low noiseSuperHEMT device designed for DBS application from EudynaDevice USA Inc amplifier using the microstrip technology. It isthe LNA that mainly determines the noise figure of the system.Low power dissipation and small integrated area are also someimportant factors that must be considered in the design of thedevices for wireless applications [6]. Based on S-parameters ofthe transistor and certain performance requirements, a systematicprocedure is developed for the design of LNA. In LNA design,the most important factors are low noise, moderate gain,matching and stability [7]. Besides those factors, powerconsumption and layout design size also need to be consideredin designed works.The characteristic of this commercialize LowNoise Amplifier are shows in Table 1 below -Table 1: FHX76LP CharacteristicComponent Parameter ValueFrequency Range 5000-6000MHzFHX76LP Associated Gain 12dBNoise Figure 0.4 dBInput IP3 8dBmOutput P1dB 9dBmII. LNA Circuit DesignA Single stage LNAA single stage microwave transistor amplifier canbe modeled by the circuit in Figure 1 where a matchingnetwork is used both sides of the transistor to transform theinput and output impedance ZA to the source and loadimpedance Zs and ZL. The most useful gain definition foramplifier design is the transducer power gain, whichaccounts both source and load mismatch [8].Figure 1: Single Stage LNA circuit978-1-4244-2215-9/08/$25.00 C2008 IEEE. 136Various type of matching technique can be applied toimplement the matching network. The lump element matching isselected for this research work. The purpose of the calculationprocess is to predict the result for LNA design. MATLAB isused to simplify the calculation process. The calculation processbegins with S-parameter selection for frequency 5 GHz to 6GHz. In this paper, S-parameter is selected at bias point Vds=2V and Ids= 10 mA from data sheet.B Stability ConsiderationOne of the most important factors in high frequencyamplifier design is to determine stability of the given bias point.Equations in Table 2 and Table 3 are used to determine thestability and stability circle of the amplifier.TABLE 2Stability determination by formula(2)r1 = 1'* S 4S12S211rsOUT L 22 +12S21F51-1115sBy combining the two formulas above, reflectioncoefficient of input/output matching circuits can becalculated by:B1 - B12 -_41 C1 22C1FLMB2 - B22 -41 C2122C2(3)(4)WhereStability CriteriaUnconditionally K > 1 & A 1< 1stablePotentially unstable K > 1 & A> 1 orK <1 & A l<1Stability FactorK 1-I SI 12 -I 22 12 +1A 1221 S12S2211Delta Factor A = Si1 s22 - SI2 21TABLE 3Stability determination by stability circleS12S21 S12S21Yin -122 rout 12-1IS-l1 IA12 S22 -1 A12(Radius) (Radius)C _(Sil - AS*22 ) C (S22 - AS11i)*I1s51 -IA 22 -IA(Center) (Center)The input and the output circuits should be matched todeliver maximum power to the load. After stability of activedevice is determined, input and output matching circuits shouldbe designed so that reflection coefficient of each port can becorrelated with conjugate complex number as given below:B1 =1+ ISll I' - S22 12 - A 12 (5)B2 =1+1 22 12 -_ 12 - A 2 (6)1C = 11 - V22 (7)C2 = E22 - VS11 (8)v =1'11 22 - 12321(9)The formulas above give source and load reflectioncoefficients to obtain maximum power gain.C Noise Figure and Constant Noise CircleSignals and noises applied to the input port ofamplifier are amplified by the gain of the amplifier andnoise of amplifier itself is added to the output. Therefore,SNR (Signal to Noise Ratio) of the output port is smallerthan that of the input port. The ratio of SNR of input port tothat of output port is referred to as noise figure and is largeror less than 1.Typically, noise figure of 2-port transistor hasa minimum value at the specified admittance given byformula:GN ls optF = F. + RN I t- 12GS(10)r- 8_ 12 21 LFIN =FS =SII+ SIF22 L(1)137D Design for minimum Noise FigureLow noise amplifier is important for receiver becausenoise figure of the amplifier of receiver affects noise figure ofthe whole system. To get minimum noise figure using 2-porttransistor, source and load reflection coefficient should matchwith Fopt and load reflection coefficient should match withFout with a complex conjugate number [9],[10] as formulabelow:Fs -F (11)O7414H5OGHz- 20GHzNWAIKCS(ckt Circui 1)H.OGHzNVAM580GHzIN A!Figure 3: LNA stability circleFL =OUt S22 +S12S21 )1-S11rs) (12)III. RESULT AND DISCUSSIONFor the proposed single stage LNA shown in Figure 1, thesimulation result is shown in Figure 2 to Figure 5. The designLNA required two 2 V supply voltage and consumes 4.5mW. Inthe beginning of the simulation process, the transistor is modeledin schematic using data sheet provided by manufacturer. Thesimulation result might not be accurate because the library hasno data and modeled of the transistor FHX76LP Low noiseSuperHEMT in Ansoft Designer. However. Duroid 5880 isbeing used as the microstrip substrate and the characteristic ofthis substrate. The comparison S-parameter simulated result asshown in Table 3.Ansoft CorporationXY Plot 2Circuiti08:ftS~2000-.0o0 , ! I5. 0P 5. .D 5.40 5.. 0 5.iF[GHz]Figure 4: LNA simulation result at 5.80 GHzY1dB(K)NWA1IXY 5.81 221"Min AnsftCorprationCircuii1tg-uoX1.4-zC31A40'540 R 6''''F [GHz]Figure2: LNA stability Figure 5: LNA noise figure138Y1dB(Sl 1JNWAlXY: 5.80 -1 5____1_dB(S21)NVA1XY: 5 801 269Y1dB(S22)NVVAlXY:5.80H656Y1NFNWA1XY 885M136Yi VdB(S12)NVWA1XY 580-4T8707:54:26 Y1dBi'NF)NA1XY 530 325.40 6.0F [GHz]6.0Ansoft Cogrporaionimio.3A..m7-..TABLE 3S-Parameter simulation resultA 5.8GHz low noise single stage amplifiers based onFHX76LP Low noise SuperHEMT transistor was designed andthe prototype was tested at room temperature. At 2V collectorbias on 5.8 GHz , this LNA has noise figure 1.32dB, with inputreturn loss of -1.63dB, insertion loss of -47.90dB and outputreturn loss of -6.24dB. Usually, as long as the stability factor anddelta factor are known as unconditionally stable, the stabilitycircle is necessary to be proved because the amplifier is stable atall area within the smith chart [9].IV. CONCLUSIONThe research work has yield a new Low Noise Amplifier(LNA) circuit' design for frequency of 5.75 GHz to 5.85 GHzand circuit simulation were done in Ansoft Designer. LNA hassuccessfully simulated with 26.92 dB gain and 1.32 dB noisefigure at frequency 5.8 GHzREFERENCES[1] Heng Jin and C.A.T. Salama, "A 1-V, 1.9- GHz CDMA, CMOS on SOI, lownoise amplifier," in SOI Conference, 2000 IEEE International.[2] T. Lee, The Design of CMOS Radio-Frequency Integrated Circuits,Cambridge University Press, 1998.[3] B. Jung Jang, I. Bok Yom, S. Pal Lee (2001). "V-Band MMIC Low NoiseAmplifier Design Based on Distributed Active Device Model",Proceedings of APMC2001, IEEE, 2001. 25-28.[4] Sungkyung Park and Wonchan Kim, "Design of a 1.8 GHz low-noiseamplifier for RF front-end in a 0.8," Consumer Electronics, IEEETransactions on, vol. 47, no. 0098, 2001.[5] A. Parssinen, S. Lindfors, J. Ryynanen, S.I. Long, and K. Halonen, "1.8 GHzCMOS LNA with on-chip DCcoupling for a subsampling direct," inCircuits and Systems, 1998. ISCAS '98. Proceedings of the 1998 IEEEInternational Symposium on, 1998, vol. 2, pp. 73-76.[6] D.M. Pozar(2000). "Microwave and RF Wireless System", United States ofAmerica: John Wiley and Sons Inc. 77-97, 205-207.[7] G. Gonzalez (1997). " Microwave Transistor Amplifier: Analysis andDesign", 2nd Edition, Upper Saddle River, NJ: Prentice - Hall Inc. 217,294-303.[8] D. M. Pozar (1998). " Microwave Engineering", 2nd Edition, United Statesof America: John Wiley and Sons Inc. 258-266, 600-605.[9] T.K.K. Tsang and M.N. El-Gamal, "Gain and frequency controllable sub-I V5.8 GHz CMOS LNA," in Circuits and Systems, 2002. ISCAS 2002. IEEEInternational Symposium on, 2002, vol. 4, pp. IV-795-IV-798.[10]E.H. Fooks and R.A. Zakarevicius (1990). "Microwave Engineering UsingMicrostrip Strips", Australia: Prentice Hall. 46, 131-133.139Frequency S11 S12 S21 S225.75Ghz -2.27 -47.19 27.76 -7.26dB dB dB dB5.80Ghz -1.63 -47.90 26.92 -6.24dB dB dB dB5.85Ghz -1.15 -48.41 26.28 -6.18dB dB dB dB

5-6 GHz Front End Low Noise Amplifier

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5-6 GHz Front End Low Noise Amplifier

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