Parameter Analysis and Design of A 1.5GHz, 15mw Low Noise Amplifier

Transcription

1 0 International Conference on Circuit, Sytem and Simulation IPCSIT vol.7 (0 (0 IACSIT Pre, Sinapore Parameter Analyi and Dein of A.5GHz, 5mw Low Noie Amplifier Dan Zhan, Wei Wu Collee of Science, Shanhai Univerity Abtract. In thi paper, we analyze parameter like noie fiure, input impedance match, ain, and linearity of the low noie amplifier (LNA and dein a.5ghz, 5mw LNA with inductive ource deeneration. Keyword: low noie amplifier, LNA dein. Introduction The increain demand for portable wirele equipment, uch a cell phone, GPS, Bluetooth (.4GHzha purred reat improvement in low-power F circuit with hih reliability. The low noie amplifier (LNA, which i the firt block in the F receiver front end (hown in Fi., play a inificant role in amplifyin weak inal reachin the antenna while at the ame time reduce noie and maintain a low power conumption. Thu, when deinin a LNA that meet pecific performance requirement, one hould take into conideration the ain, power, noie fiure, input and output impedance match (the S- parameter, and linearity of the LNA. Fi.. Hihly implified tructure of the receiver Fi.. Baic topoloy of LNA The inductive ource deenerated cacode LNA topoloy, hown in Fi., ha demontrated the potential for excellent impedance matchin, noie fiure, and power diipation [] when compared to LNA that ha reitive termination, / m termination, or hunt-erie feedback of the input port. In ection, we tudy everal baic parameter of the LNA with inductive ource deeneration; in ection, we offer an example of the dein of a LNA; in ection 4, we ue ADS and PSPICE to analyze the performance of the deined LNA.. Parameter analyi The followin paae will tudy the noie fiure, input impedance match, ain, and linearity of the inductive ource deenerated cacode LNA... Noie fiure (NF

2 The noie fiure i the ratio between the total output noie power due to all noie ource and the output noie power enerated by the ource internal reitance []. The LNA hould not brin too much noie to the followin part of the receiver in order to elect and amplify the weak inal, o keepin a low NF i a crucial proce when deinin the LNA. Accordin to the n-tae network Frii equation: ( NF ( NFn NFtot = + ( NF , Ap Ap... Ap( n where A p i the ain of the tae and i uually hih, we can dicard the noie contribution of the later tae on overall noie fiure calculation [], which mean we could only focu on the noie ituation of M, which i hown in Fi.. Fi.. Equivalent mall inal circuit of M Fi.4. More hardware in the input matchin network It contain current noie in drain ( i nd, current noie in ate ( i n = i n, c + i n, u, reitance noie from and L ( i and i L + γχ ω0 L.The noie fiure of uch LNA can be expreed a: F = + + ( (, αql ωt δα δα where χ = κ + ξ = + cql ( QL 5γ + 5γ + (. δ i the ate noie, γ i the thermal noie in the channel m of M, α = (α = in lon-channel device, Q L i the quality factor of input match network and equal d 0, C = WLCox, c =0.95 (even conider the hort-channel effect [4], ω 0 i the work frequency ω0c m and ωt i the reonance frequency. C 5γ From ( and (, we can eaily realize that when Q L, = + ( Q L, i uually between.5 and 5.5, δα 5 5 if the channel reitance i conidered, then Q =,, + γ γ L r c δα + δα [5], F reache it minimum that L + γ ω0 δα δα δα equal: + + ( [ c + ( + ], and we can deduce the bet channel width a: α ω 5γ 5γ 5γ W = ( LC ω Q ox 0 l,.. Input impedance match T In Fi., the input impedance of the LNA can be expreed a: Zin = L + L + + Z, where Z = L + + ω L. Therefore, we can adjut L to make the input impedance that equal (50 Ω when T C workin frequency i near ω 0, which mean Zin = e( Zin = ωt L ( nelect L and [6]. Thu, L and L can be deined a follow: L L = L. =, ωt ω0 C

3 Sometime we can add additional hardware to the input impedance matchin network to provide more deree of freedom in the dein, in order to mitiate the impact of component variation for LNA [7], hown in Fi 4, while thi tructure account for more area on the chip... Gain The mall inal analyi for cacode i hown i Fi.5. Fi.5. Small inal equivalent circuit for cacode LNA with inductive ource deeneration From thi equivalent circuit, we can acknowlede that the tranconductance ( G m of the firt tae m ωt (common -ource can be expreed a: Gm =, and the current ain C ( L + L L ω m 0 m ( A i of the econd tae (common-ate can be expreed a: Ai =. m + C Conider that m = μncox( W / L( VGS VTH, for a certain technoloy like 0.8 μm or 0.5 μ m, all parameter are fixed except the channel width. So we can increae W to achieve reater ain for the weak inal. Accordin to (, however, expandin width could elevate noie fiure and introduce more noie to the LNA. What i more, bier m mean reater drain current I D, which rie the total power conumption that equal VDD ID..4. Linearity Althouh there are many way to evaluate the linearity of the LNA, to meaure the third-order intercept point (IP i the mot commonly ued method. The IIP i obtained raphically by plottin the output power veru the input power both on loarithmic cale. Two curve are drawn: one for the linearly amplified inal at an input tone frequency, one for a nonlinear product. Both curve are extended with traiht line of lope and. The point where the curve interect i the third-order intercept point, which i hown i Fi.6. Fi.6. Third-order intercept point definition 4 Vod (0 For narrow-band LNA, the IIP can be expreed a: IIP =, where (0, QL v ( + ( v (0 ( v, ( v are tranconductance ot when the input inal voltae i 0, v, v, repectively. To obtain a hiher IIP, one can increae the overdrive voltae while at the ame time rie the power diipation, or lower the quality factor of the input circuit while woren the noie fiure of the LNA. Thu, there exit neceity to bet imize the parameter of the LNA durin deinin proce.. Dein of a.5ghz, 5mw LNA with inductive ource deeneration To dein a LNA that meet the pecific performance requirement hown in Table, one hould firt fiure out value of the important component of the LNA a follow: I = P/ V = 0mA; L = / ω C / = 4 L/( μ E = 0.6nH ; d DD T m n at L = /( ω C L = 4.nH ; 0

4 W = 500μm (4 LC ω Q ox 0 L Then we can dein a whole LNA tructure with pecific component value in Fi.7. The width of M, M, M, M4 are 500 μ m, 00 μ m, 50 μ m, 50 μ m, repectively. channel lenth (L 0.5 μ m μ n 0.05 m /V upply voltae ( V DD.5V at E V/m power (P 5mw 50 Ω workin frequency ( ω 0.5GHz l 00 Ω C ox.8mf/ m Q L 5 Table. pecific requirement for deinin Fi.7. Deinin tructure of.5hz LNA 4. Simulation reult 4.. S-parameter, NF, Stability factor and IIP We ue the Advanced Dein Sytem 006A (ADS to imize the value of inductor and capacitor, in order to achieve input and output impedance match, to obtain a relatively hiher ain toether with a maller noie fiure, and to keep tability factor reater than one. We finally et L to 0.6 nh and L to 8.5 nh. The imulation reult of S-parameter, tability factor, noie fiure, and the third-order intercept point are hown in Fi.8. When workin at the frequency of.5ghz, the LNA ha the followin property: S, S, S, NF, and IIP are -.5dB, -.490dB,.49dB,.050dB, and 5.dBm, repectively. The tability factor i., bein reater than, which indicate the LNA i table near.5ghz. (a S (b S (c S (d Stability factor (e Noie fiure (f IIP Fi.8. Simulation reult Fi.9. Output inal veru width ( 600 μ m, 500 μ m, 400 μ m 4

5 4.. The relation between ain and channel width We ue PSPICE LEVEL model which i uitable for hort-channel MOSFET to imulate the output of the deined LNA in order to tudy it ain. The proram code for the tructure in Fi.7 are provided a follow: A LNA CICUIT *.PAAM WIDTH=500U Udd 0.5V Vin 8 0 AC *Vin 8 0 SIN(0 0..5G C 0fF.6K L 4nH C4 0 pf 4 6 7K C 8 7 0p L nH L nH M NM L=0.5U W=500U *M NM L=0.5U W={WIDTH} M 5 0 NM L=0.5U W=00U M 4 0 NM L=0.5U W=50U M PM L=0.5U W=50U.MODEL NM NMOS (LEVEL= VTO= KP=4.5E-4 CBD=5P CBS=P D=5 S= DS=MEG CGSO=P CGDO=P CGBO=P.MODEL PM PMOS (LEVEL= VTO=- KP=4.5E-4 CBD=5P CBS=P D=5 S= DS=MEG CGSO=P CGDO=P CGBO=P.AC DEC 0 G 0G *.TAN 0N 00N *.STEP PAAM WIDTH LIST 400U 500U 600U.POBE.END Since m increae when the channel width of M i reater, the weak inal can be amplified further if we et a wider channel. It i proved by the imulation reult hown in Fi.9. Conider the fact that LNA lay more emphai on lowerin noie fiure than increain ain, we hould acrifice hih ain in order to reduce the output noie. Uually, the ain achieved with the minimum noie fiure i to 4dB le than the maximum value [8]. 5. Concluion The low noie amplifier (LNA i a crucial part in F receiver. It i deined for electin and amplifyin weak inal in certain frequency, reducin noie, and providin an appropriate workin condition for the followin mixer. We firt analyze ome parameter, uch a noie fiure, input impedance match, ain, and linearity, that reflect the quality of LNA. Then we deined an inductive ource deenerated cacode LNA with the workin frequency of.5ghz. The imulation reult ot from ADS and PSPICE indicate that the value of the component are appropriate and the performance of the deined LNA i acceptable. 6. eference [] A. Nieuwoudt, T. aheb, H. Nejati, Y. Maoud, Increain Manufacturin Yield for Wideband F CMOS LNA in the Preence of Proce Variation, 8th International Sympoium on Quality Electronic Dein, 007, IEEE, p [] Nejati, H.; aheb, T.; Nieuwoudt, A.; Maoud, Y., Modelin and Dein of Ultrawideband Low Noie Amplifier with Generalized Impedance Matchin Network, ISCAS 007. IEEE, p.6-65, (007 [] Nejati, H.; aheb, T.; Maoud, Y., Analytical Modelin of Common-Gate Low Noie Amplifier, ISCAS.008, IEEE, p.888 [4] T. H. Lee, The Dein of CMOS adio-frequency Interated Circuit (econd edition, Publihin Houe of Electronic Indutry, 006 [5] Jiwei Chen, Binxue Shi, Analyi and imization of the impact of channel reitance on CMOS LNA noie performance, Microelectronic Journal, p. 07-0, (00 [6] B. Chi, Z. Yu, B. Shi, Analyi and Dein of CMOS F Interated Circuit, Tinhua Pre, 006 [7] Maoud, Y.; Nieuwoudt, A.; aheb, T., Variability-Aware Synthei for Wideband Low Noie Amplifier, ISCAS 007, IEEE, p.9- [8] X.F. Xu, ADS 008 F Circuit Dein and Simulation, Publihin Houe of Electronic Indutry, p.4, (009 5