APPLICATION NOTE Thermal Optimization of GaN HEMT Transistor Power Amplifiers Using New Self-heating Large-signal Model Introduction Gallium nitride power transistors have very high RF power densities which range from 4 to 12 watts per mm of gate periphery depending on operating drain voltage. Even though GaN/AlGaN on SiC substrates have high thermal conductivity it is necessary to be aware of channel temperature rise incurred by both DC and RF stimuli when designing power amplifiers. Thermal management is even more important for broadband amplifiers (a very popular application) where drain efficiencies can vary considerably as a function of frequency. A new self-heating feature in Cree’s GaN HEMT large- signal models automatically effects both DC and RF parameters as a function of transistor drawn current. We will use the CGH40025F transistor in a 2 to 6 GHz broadband amplifier and demonstrate how the transistor operating temperature can be minimized during the simulation phase of the design. The default thermal resistance is set for the CGH40025F at 4.8 deg C/watt. The operating case temperature (Tcase) is user defined. The self-heating engine automatically calculates the rise in temperature (Trise) of the HEMT channel above Tcase. Trise can be used as a function of other parameters such as frequency, output power DCVS ID=V1 V=2.15 V and efficiency. The paper shows -006 ote: APPNOTE Application N Rev. B the direct lowering of Trise using optimization RES ID=R1 R=25 Ohm PORT P=1 Z=50 Ohm PIPAD ID=P1 Z1=50 Ohm Z2=50 Ohm DB=1.031 dB IND ID=L1 L=1.311 nH CAP ID=C2 C=11.53 pF CGH40025F_r6 ID=40025F1 TLIN ID=TL1 Z0=47.54 Ohm EL=21 Deg F0=4000 MHz Tcase=25 RTH=4.8 IND ID=L2 L=2481 nH I_METER ID=AMP1 IND ID=L3 L=0.6882 nH PORT_PS1 P=1 Z=50 Ohm PStart=-10 dBm PStop=39 dBm PStep=1 dB 4 Th CAP ID=C1 C=2.525 pF V_METER ID=VM1 CAP ID=C4 C=4.958 pF unison with the maintenance of output power. Such CAP ID=C5 C=3.057 pF thermal optimization assures reliable 2 1 CAP ID=C3 C=0.8985 pF TLIN ID=TL2 Z0=10.4 Ohm EL=17.42 Deg F0=4000 MHz in PORT P=2 Z=50 Ohm 3 operation as well as improved performance since the transistors are I_METER ID=AMP2 operating cooler. DCVS ID=V2 V=28 V Subject to change without notice. www.cree.com 1 Basic Amplifier Design 2 GHz to 6GHz Demonstration Amplifier Simulation DCVS ID=V1 V=2.15 V RES ID=R1 R=25 Ohm PORT P=1 Z=50 Ohm PIPAD ID=P1 Z1=50 Ohm Z2=50 Ohm DB=1.031 dB IND ID=L1 L=1.311 nH CAP ID=C2 C=11.53 pF IND ID=L2 L=2481 nH TLIN ID=TL1 Z0=47.54 Ohm EL=21 Deg F0=4000 MHz CGH40025F_r6 ID=40025F1 Tcase=25 RTH=4.8 I_METER ID=AMP1 2 IND ID=L3 L=0.6882 nH 1 CAP ID=C3 C=0.8985 pF 4 Th CAP ID=C1 C=2.525 pF V_METER ID=VM1 TLIN ID=TL2 Z0=10.4 Ohm EL=17.42 Deg F0=4000 MHz CAP ID=C4 C=4.958 pF CAP ID=C5 C=3.057 pF PORT P=2 Z=50 Ohm 3 I_METER ID=AMP2 PORT_PS1 P=1 Z=50 Ohm PStart=-10 dBm PStop=39 dBm PStep=1 dB DCVS ID=V2 V=28 V Figure 1 - 2 to 6 GHz, 25 W Broadband PA Schematic Figure 1 shows the basic schematic of a broadband, 2 to 6 GHz, power amplifier utilizing a Cree CGH40025F GaN HEMT transistor. This device operates from a nominal 28 volt rail. The transistor symbol in the schematic shows a 4 port device – gate, drain, source and temperature monitor – a voltmeter serves as the “thermometer”. Initial circuit design was concentrated on achieving broadband and flat small signal gain across the wanted frequency range (Figure 2). The power transfer characteristics of the amplifier were then simulated. For example, at a constant CW input power of 38 dBm the output power is plotted as a function of frequency in Figure 3 where it can be seen that the output power varies somewhat due to different levels of compression and impedance match. Copyright © 2009-2010 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree and the Cree logo are registered trademarks of Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. Cree Confidential and Supplied under terms of the Mutual NDA. 2 APPNOTE-006 Rev. C Cree, Inc. 4600 Silicon Drive Durham, NC 27703 USA Tel: +1.919.313.5300 Fax: +1.919.869.2733 www.cree.com/wireless Simulated Performance Prior To Optimization S21 S11 S22 20 Output Power v Frequency 45 p100 p92 p93 p94 p95 p96 p97 p98 p99 p82 p83 p84 p85 p86 p87 p88 p89 p90 p72 p73 p74 p75 p76 p77 p78 p79 p80 p62 p63 p64 p65 p66 p67 p68 p69 p70 p52 p53 p54 p55 p56 p57 p58 p59 p60 p91 p81 p71 p61 p51 10 p1 dB 0 p42 p43 p44 p45 p46 p47 p48 p49 p50 p32 p33 p34 p35 p36 p37 p38 p39 p40 p22 p23 p24 p25 p26 p27 p28 p29 p30 p12 p13 p14 p15 p16 p17 p18 p19 p20 p10 p41 p31 p21 p11 p2 p3 p4 p5 p6 p7 p8 p9 p1 dBm 44 43 -10 DB(|S(1,1)|) 2 to 6 GHz thermal example -20 DB(|S(2,2)|) 2 to 6 GHz thermal example DB(|S(2,1)|) 2 to 6 GHz thermal example -30 2000 3000 p1: Pwr = 38 dBm p 1 : P wr = p 2 -: 1 0P wdr B m=p 3 -: 9 P d wB r m =p 4 -: 8 P d w Br m =p 5 -: 7 P dwBr m = p 6 -: 6 Pdw B r m =p 7 -: 5 P d w Br m = - 4 d B m p 8 : P wr = p 9 -: 3 PdwBr m =p 1 -0 2: d PB w mr p = 1 1 -: 1 P dwBr mp =1 2 0 : dPBw m r p =1 3 1: dP B w mr p = 1 4 2: d P Bwmr = 3 d B m p 1 5 : P w r p =1 6 4 : dPBw m r p =1 7 5: d PB w mr p = 1 8 6: d P Bwmr p =1 9 7 : dPBw m r p =2 0 8: dP B w mr p = 2 1 9: d P Bwmr = 1 0 d Bm p 2 2 : P w r p =2 3 1 : 1 Pdw B r mp =2 4 1: 2 P d w Br mp = 2 5 1: 3 P dwBr mp =2 6 1 : 4 Pdw B r mp =2 7 1: 5 P d w Br mp = 2 8 1: 6 P dwBr m = 1 7 d Bm p 2 9 : P w r p =3 0 1 : 8 Pdw B r mp =3 1 1: 9 P d w Br mp = 3 2 2: 0 P dwBr mp =3 3 2 : 1 Pdw B r mp =3 4 2: 2 P d w Br mp = 3 5 2: 3 P dwBr m = 2 4 d Bm p 3 6 : P w r p =3 7 2 : 5 Pdw B r mp =3 8 2: 6 P d w Br mp = 3 9 2: 7 P dwBr mp =4 0 2 : 8 Pdw B r mp =4 1 2: 9 P d w Br mp = 4 2 3: 0 P dwBr m = 3 1 d Bm p 4 3 : P w r p =4 4 3 : 2 Pdw B r mp =4 5 3: 3 P d w Br mp = 4 6 3: 4 P dwBr mp =4 7 3 : 5 Pdw B r mp =4 8 3: 6 P d w Br mp = 4 9 3: 7 P dwBr m = 3 8 d Bm p 5 0 : P w r p =5 1 3 : 9 Pdw B r mp =5 2 -: 1 0 P w dr Bp m= 5 3 -: 9 P dwBr mp =5 4 -: 8 Pdw B r mp =5 5 -: 7 P d w Br mp = 5 6 -: 6 P dwBr m = - 5 d Bm p 5 7 : P w r p =5 8 -: 4 Pdw B r mp =5 9 -: 3 P d w Br mp = 6 0 -: 2 P dwBr mp =6 1 -: 1 Pdw B r mp =6 2 0: dP B w mr p = 6 3 1: d P Bwmr = 2 d B m p 6 4 : P w r p =6 5 3 : dPBw m r p =6 6 4: d PB w mr p = 6 7 5: d P Bwmr p =6 8 6 : dPBw m r p =6 9 7: dP B w mr p = 7 0 8: d P Bwmr = 9 d B m p 7 1 : P w r p =7 2 1 : 0 Pdw B r mp =7 3 1: 1 P d w Br mp = 7 4 1: 2 P dwBr mp =7 5 1 : 3 Pdw B r mp =7 6 1: 4 P d w Br mp = 7 7 1: 5 P dwBr m = 1 6 d Bm p 7 8 : P w r p =7 9 1 : 7 Pdw B r mp =8 0 1: 8 P d w Br mp = 8 1 1: 9 P dwBr mp =8 2 2 : 0 Pdw B r mp =8 3 2: 1 P d w Br mp = 8 4 2: 2 P dwBr m = 2 3 d Bm p 8 5 : P w r p =8 6 2 : 4 Pdw B r mp =8 7 2: 5 P d w Br mp = 8 8 2: 6 P dwBr mp =8 9 2 : 7 Pdw B r mp =9 0 2: 8 P d w Br mp = 9 1 2: 9 P dwBr m = 3 0 d Bm p 9 2 : P w r p =9 3 3 : 1 Pdw B r mp =9 4 3: 2 P d w Br mp = 9 5 3: 3 P dwBr mp =9 6 3 : 4 Pdw B r mp =9 7 3: 5 P d w Br mp = 9 8 3: 6 P dwBr m = 3 7 d Bm p 9 9 : P w r p =1 0 3 0 8: dP B w mrp 1 = 0 1 3: 9 P dwBrp m1 =0 2 -: 1 0P w d rp B1m=0 3 -: 9 P d wB r pm1 = 0 4 -: 8 P dwBrpm1 =0 5 -: 7 PdwBr m = - 6 d Bm p 1 0 6 : P w r p 1 =0 7 -: 5 P d w Brpm1 = 0 8 -: 4 P dwBrp m1 =0 9 -: 3 Pdw B rp m1 =1 0 -: 2 P d wB r pm1 = 1 1 -: 1 P dwBrpm1 =1 2 0: dPBwmr = 1 d Bm p 1 1 3 : P w r p 1 =1 4 2: dP B w mrp 1 = 1 5 3: d P Bwmrp 1 =1 6 4 : dPBw m rp 1 =1 7 5 : dP B wm rp 1 = 1 8 6: d P Bwmrp 1 =1 9 7: dPBwmr = 8 d Bm p 1 2 0 : P w r p 1 =2 1 9: dP B w mrp 1 = 2 2 1: 0 P dwBrp m1 =2 3 1 : 1 Pdw B rp m1 =2 4 1 : 2 Pd wB r pm1 = 2 5 1: 3 P dwBrpm1 =2 6 1: 4 PdwBr m = 1 5 d Bm p 1 2 7 : P w r p 1 =2 8 1: 6 P d w Brpm1 = 2 9 1: 7 P dwBrp m1 =3 0 1 : 8 Pdw B rp m1 =3 1 1 : 9 Pd wB r pm1 = 3 2 2: 0 P dwBrpm1 =3 3 2: 1 PdwBr m = 2 2 d Bm p 1 3 4 : P w r p 1 =3 5 2: 3 P d w Brpm1 = 3 6 2: 4 P dwBrp m1 =3 7 2 : 5 Pdw B rp m1 =3 8 2 : 6 Pd wB r pm1 = 3 9 2: 7 P dwBrpm1 =4 0 2: 8 PdwBr m = 2 9 d Bm p 1 4 1 : P w r p 1 =4 2 3: 0 P d w Brpm1 = 4 3 3: 1 P dwBrp m1 =4 4 3 : 2 Pdw B rp m1 =4 5 3 : 3 Pd wB r pm1 = 4 6 3: 4 P dwBrpm1 =4 7 3: 5 PdwBr m = 3 6 d Bm p 1 4 8 : P w r p 1 =4 9 3: 7 P d w Brpm1 = 5 0 3: 8 P dwBr m = 3 9 d Bm 4000 Frequency (MHz) DB(PT(PORT_2))[X,49] (dBm) 2 to 6 GHz thermal example 42 p142 p143 p144 p145 p146 p147 p148 p149 p150 p132 p133 p134 p135 p136 p137 p138 p139 p140 p122 p123 p124 p125 p126 p127 p128 p129 p130 p112 p113 p114 p115 p116 p117 p118 p119 p120 p102 p103 p104 p105 p106 p107 p108 p109 p110 p141 p131 p121 p111 p101 5000 41 2000 6000 Figure 2 - S21, S11 and S22 prior to optimization The self-heating feature of the large-signal in the transistor from package flange to channel. operating drain current. Optimization parameters were set up in Microwave Office for output ensure that the transistor’s channel temperature never exceeds 225°C at a case temperature of 85°C i.e. a temperature rise of 140°C. 3235 MHz 167.3 V 100 p1 50 |Vcomp(V_METER.VM1,0)|[X,49] (V) 2 to 6 GHz thermal example 0 2000 3000 4000 Frequency (MHz) APPNOTE-006 Rev. C p1: Pwr = 38 dBm 5000 6000 Figure 4 - Transistor temperature rise above Tcase prior to optimization Copyright © 2009-2010 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree and the Cree logo are registered trademarks of Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. Cree Confidential and Supplied under terms of the Mutual NDA. 3 6000 Temperature Rise power, gain and temperature rise as a function of frequency. The intention of the optimization is to 5000 150 Degrees C any specific attention has been taken to decreasing 4000 Frequency (MHz) Figure 3 - Output Power vs. frequency at Pin=38 dBm prior to optimization 200 model automatically calculates the thermal rise This is shown in Figure 4 for the amplifier before 3000 Cree, Inc. 4600 Silicon Drive Durham, NC 27703 USA Tel: +1.919.313.5300 Fax: +1.919.869.2733 www.cree.com/wireless Simulated Performance After To Optimization Following thermal optimization the small signal parameters are re-simulated as shown in Figure 5 where there is little change in gain and some improvement in output return loss. Figure 6 shows the CW output power as a function of frequency – again there is general improvement in output power over the band even though the “profile” has changed. S21 S11 S22 12 10 44.5 5 p1 44 -5 p110 p142 p143 p144 p145 p146 p147 p148 p149 p150 p132 p133 p134 p135 p136 p137 p138 p139 p140 p122 p123 p124 p125 p126 p127 p128 p129 p130 p112 p113 p114 p115 p116 p117 p118 p119 p120 p102 p103 p104 p105 p106 p107 p108 p109 p141 p131 p121 p111 p101 p42 p43 p44 p45 p46 p47 p48 p49 p50 p32 p33 p34 p35 p36 p37 p38 p39 p40 p22 p23 p24 p25 p26 p27 p28 p29 p30 p12 p13 p14 p15 p16 p17 p18 p19 p20 p10 p41 p31 p21 p11 p2 p3 p4 p5 p6 p7 p8 p9 p1 dBm 0 dB Output Power v Frequency 45 p100 p92 p93 p94 p95 p96 p97 p98 p99 p82 p83 p84 p85 p86 p87 p88 p89 p90 p72 p73 p74 p75 p76 p77 p78 p79 p80 p62 p63 p64 p65 p66 p67 p68 p69 p70 p52 p53 p54 p55 p56 p57 p58 p59 p60 p91 p81 p71 p61 p51 43.5 43 -10 DB(|S(1,1)|) 2 to 6 GHz thermal example 42.5 DB(|S(2,2)|) 2 to 6 GHz thermal example -15 -20 2000 p 1: P wr = p 8: P wr = p 15: DB(|S(2,1)|) 2 to 6 GHz thermal example p 22: = = 4000 Frequency (MHz) P wr P wr P wr P wr P wr P wr = P wr = p 92: P wr = p 99: P wr = P wr P wr P wr P wr - 1 0p 2d: B m P wr = = 4 pd1B6 :m P wr 1 1p 2d3 :B m P w r = - 9 pd3 :B m P w r P wr = Pw r Pw r 5 pd1 7 Bm : Pw r = - 3p 5 9 d B: m P w r 4 pd6 6 Bm : Pw r - 8 p4 d :B m P w r = = - 1p 1 1 d B: m P w r 6 p1 d8 Bm : Pw r - 7 p5 d B: m P w r = = = = - 9p 5 3 d B: m P w r 5 p6 d7 Bm : Pw r 1 2p 7 4 d B: m P w r = = 2 0p 3 2 d B: m P w r - 2p 6 0 d B: m P w r = = 2 7p 3 9 d B: m P w r 3 4p 4 6 d B: m P w r = = = = 3 2p 9 4 d B: m P w r 3p91 0 d1B: m P w r 1 3p 2 5 d B: m P w r = = 1 8p 8 0 d B: m P w r 2 5p 8 7 d B: m P w r P wr 7 p1 d B9m : P wr = - 6 p d6B: m P w r = P wr 8 p d2B0m : = = = P wr 3 6 p 4d8B: m P w r = = = = 3 4p 9 d6B: m P w r P wr 1 5 p 2d7B: m P w r 2 2 p 3d4B: m P w r 2 9 p 4d1B: m P w r = = 2 0p 8 d2B: m P w r 2 7p 8 d9B: m P w r -p 9 1 0d3B: m P w r 1 p d1B3m : = = = - 8p 5 d4B: m P w r 6 p6 d B8m : 1 3p 7 d5B: m P w r = = 2 1p 3 d3B: m P w r - 1p 6 d1B: m P w r = = -p 1 0 2d: B m P wr 2 8p 4 d0B: m P w r 3 5p 4 d7B: m P w r = = = = 3 3p 9 5 d B: m P w r 0 p1 d B2m : 1 4p 2 d6B: m P w r = = 1 9p 8 1 d B: m P w r 2 6p 8 8 d B: m P w r - 5 pd7B: mP w r = 9 pd2B1 :m = = P wr = = P wr - 4 = P wr 8 pd7B0 :m P wr d Bm d Bm d Bm 9 d Bm 16 = d Bm 23 d Bm 30 d Bm 37 d Bm - 6 d Bm = -p 3 1 0 d9B: mP w r = -p 2 1 1d0B: m P w r = -p 11 1d1 B : m P wr = 0p 1d1 2 B :m P wr = 1 d Bm Pw r = 3p 1 1 d B5m : = 4p 1 1 d B6m : = 5p 1 d1B7m : = 6 p 1d1B8 :m P wr = 7p 1d1 9 B :m P wr = 8 d Bm Pw r = 1p01 2 d2B: m P w r 1 p 31 2d5 B : m P wr = 1p41 2 d 6B : m P wr = 15 = P wr 1p71 2 d9B: m P w r = = P wr 1p 1 2 d3B: mP w r 1p 8 1 3 d0B: mP w r = = P wr 1p 2 1 2d4B: m P w r 1p 9 1 3d1B: m P w r = = 2 p 01 3d2 B : m P wr = 2p11 3 d 3B : m P wr = 22 d Bm d Bm P wr = 2p31 3 d 5 B: m P w r = 2p41 3 d6B: m P w r = 2p 5 1 3 d7B: mP w r = 2p 6 1 3d8B: m P w r = 2 p 71 3d9 B : m P wr = 2p81 4 d 0B : m P wr = 29 d Bm P wr = 3p01 4 d 2 B: m P w r = 3p11 4 d3B: m P w r = 3p 2 1 4 d4B: mP w r = 3p 3 1 4d5B: m P w r = 3 p 41 4d6 B : m P wr = 3p51 4 d 7B : m P wr = 36 d Bm p 148: P wr = 3p71 4 d 9 B: m P w r = 3p81 5 d0B: m P w r = 3 9 2000 6000 Figure 5 - S21, S11 and S22 after optimization 3000 4000 Frequency (MHz) 5000 6000 Figure 6 - Output Power vs. frequency at p1: Pwr = 38 dBm 42 dB m 5000 DB(PT(PORT_2))[X,49] (dBm) 2 to 6 GHz thermal example d Bm d Bm d Bm d Bm - 5 2 = = d Bm 38 = = = = 3 6p 9d8 :B m P w r d Bm 10 17 24 31 = = 2 2p 8d4 :B m P w r 2 9p 9d1 :B m P w r -p71 0 d 5B : m P wr 3 = = = - 6p 5d6 :B m P w r 1 pd6B3 :m 1 5p 7d7 :B m P w r = = 2 3p 3d5 :B m P w r 3 0p 4d2 :B m P w r 3 7p 4d9 :B m P w r = = = = 3 5 p 9d7B: m P w r P wr 1 6p 2d8 :B m P w r = P wr 7 p d6B9m : 2 1 p 8d3B: m P w r 2 8 p 9d0B: m P w r -p 81 0d4 B : m P wr 2 pd1B4 :m = = = = - 7 p 5d5B: m P w r 0 p d6B2m : 1 4 p 7d6B: m P w r = -p41 0 d8B: m P w r 2p 1d1 4 Bm : 9p 1d2 1 Bm : 1p61 2 d 8 B: m P w r = = = = 3 3p 4 5 d B: m P w r 1 1p 7 3 d B: m P w r = = 1 9p 3 1 d B: m P w r 2 6p 3 8 d B: m P w r - 1p05 2 d: B m Pw r = = = = 3 1p 9d3 :B m P w r -p51 0 d 7 B: m P w r 1 2p 2 4 d B: m P w r = = = 1 7p 7d9 :B m P w r 2 4p 8d6 :B m P w r 3 8p 1d0 0 Bm : - 2 pd1 0 Bm : = = = 3 9p 5d1 :B m P w r - 4p 5d8 :B m P w r 3 pd6B5 :m 1 0p 7d2 :B m P w r = = = = = 1 8p 3d0 :B m P w r 2 5p 3d7 :B m P w r 3 2p 4d4 :B m P w r = = = = p 78: p 85: p 106: - 3 pd9B: m P w r = = P wr P wr p 43: p 50: p 57: p 64: p 71: 3000 P wr P wr p 29: p 36: p 113: p 120: p 127: p 134: p 141: Pin=38 dBm after optimization Figure 7 is a plot of transistor drain current as a function of frequency which indicates drain current reduction of as much as 12% compared to the original design. Figure 8 indicates the temperature rise after thermal optimization showing temperature decreases of as much as 35°C compared to the original design. Drain Current versus Frequency 1800 p1 Temperature Rise 150 1600 p1 1200 |Icomp(I_METER.AMP2,0)|[X,49] (mA) 2 to 6 GHz thermal example 1000 800 50 p1: Pwr = 38 dBm |Vcomp(V_METER.VM1,0)|[X,49] (V) 2 to 6 GHz thermal example 600 2000 3000 4000 Frequency (MHz) 5000 6000 Figure 7 - Drain current vs. frequency at 3250 MHz 132.5 V 100 Degrees C Milliamps 1400 Pin of 38 dBm after optimization 0 2000 3000 4000 Frequency (MHz) APPNOTE-006 Rev. C 5000 6000 Figure 8 - Transistor temperature rise above Tcase after optimization Copyright © 2009-2010 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree and the Cree logo are registered trademarks of Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. Cree Confidential and Supplied under terms of the Mutual NDA. 4 p1: Pwr = 38 dBm Cree, Inc. 4600 Silicon Drive Durham, NC 27703 USA Tel: +1.919.313.5300 Fax: +1.919.869.2733 www.cree.com/wireless Conclusion This paper has shown a demonstration of how to use the self-heating feature of Cree’s large-signal GaN HEMT models to calculate transistor temperature rise as a function of other parameters such as frequency and RF power level. Specifically the self-heating engine has been used, via optimization, to lower transistor temperature by minimizing Trise while maintaining output power. Reference Cree, Inc. proprietary large-signal model CGH40025F_r6 for Applied Wave Research’s Microwave Office generated the results in this application note. Copyright © 2009-2010 Cree, Inc. All rights reserved. The information in this document is subject to change without notice. Cree and the Cree logo are registered trademarks of Cree, Inc. Other trademarks, product and company names are the property of their respective owners and do not imply specific product and/or vendor endorsement, sponsorship or association. Cree Confidential and Supplied under terms of the Mutual NDA. 5 APPNOTE-006 Rev. C Cree, Inc. 4600 Silicon Drive Durham, NC 27703 USA Tel: +1.919.313.5300 Fax: +1.919.869.2733 www.cree.com/wireless