Microwave Devices Microwave Passive Devices I 2 2008

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Microwave Devices - Microwave Passive Devices I - 2 2008 / 1 학기 서광석

Microwave Devices - Microwave Passive Devices I - 2 2008 / 1 학기 서광석 • S. N. U. EE Microwave Devices 2008

Transmission Line VVV UUU • Lossless 전송선 의 경우 : (R=G=0) • 전송선의 길이가

Transmission Line VVV UUU • Lossless 전송선 의 경우 : (R=G=0) • 전송선의 길이가 l 인 경우 phase shift delay: C delay 줄임 • S. N. U. EE Microwave Devices 2008

Microwave Transmission Line • Microwave transmission line 1. coaxial cable 2. waveguide 3. planar

Microwave Transmission Line • Microwave transmission line 1. coaxial cable 2. waveguide 3. planar transmission line * Ref : Practical Microwaves, Chap. 3 1. coaxial cable z a b • S. N. U. EE • Dielectric material - PTFE(polytetrafluroethylene) : r = 2. 1 • Mode : TEM mode (Ez=Hz=0) TE mode (Ez=0) TM mode (Hz=0) Microwave Devices 2008

Coaxial Cable (1) For f < f. C (TE 11 mode, , where a

Coaxial Cable (1) For f < f. C (TE 11 mode, , where a and b in inches ), - TEM mode exists. (no cut-off frequency for TEM mode) - Zo: independent of frequency 0. 9 f. C 까지 coaxial cable을 사용하는 것이 일반적으로 추천됨. high freq. 용의 경우 f. C a , b (Example) 0. 085” semi - rigid cable a = 0. 0201”, b = 0. 066” r = 2. 10 ( ~ 40만원 / 2 feet) ZO = 49. 47 f. C = 60 GHz (50 GHz까지 사용) 0. 047” semi - rigid cable f. C = 110 GHz ( m precision machining 필요, connector 가격 ~ 수백$ ) * a, b 가 작을 경우 attenuation loss증가 , power handling 감소 , 가격 상승 • S. N. U. EE Microwave Devices 2008

Coaxial Cable (2) Attenuation coefficient 0. 085” cable - 0. 73 d. B/ft @10

Coaxial Cable (2) Attenuation coefficient 0. 085” cable - 0. 73 d. B/ft @10 GHz 0. 25” cable - 0. 29 d. B/ft @10 GHz (line length가 클 경우, optical fiber로 대체 필요) Coaxial cable의 장점 : 1. dc to fc 까지 동작 (TEM mode 로 인해) 2. frequency independent 3. Radiation loss 없음 Coaxial cable의 Type - flexible cable : outside conductor, high loss - semi-rigid cable : outside conductor – metal (Ag-coated Cu), 1번만 bent 가능 Micro–coaxial cable Dielectric filled metal substrate • S. N. U. EE • MEMS 기술로 제작 가능 - high cost process Microwave Devices 2008

Waveguide 2. waveguide - Standard : a=2 b z - 경계 조건 : tangential

Waveguide 2. waveguide - Standard : a=2 b z - 경계 조건 : tangential E field = 0 at metal walls mode 발생 b Ey a § Air-filled waveguide 의 경우 (TEmn mode) dominant node: TE 10 mode Hx TE 10 mode (Ez=0, Hz 0) (a=2 cm) - f. C 10 에서 TM 11 mode 의 cut -off 까지 사용가능 - 각 주파수 별로 사용되는 wave-guide size 결정 * dielectric filled에 비해 air - filled가 사용 주파수에서 a , b 증가 • S. N. U. EE Microwave Devices 2008

Modes in Waveguide Ref : D. M. Pozar, “Microwave Engineering”, Chap. 3 • S.

Modes in Waveguide Ref : D. M. Pozar, “Microwave Engineering”, Chap. 3 • S. N. U. EE Microwave Devices 2008

Planar Transmission Line 3. planar transmission line a. Microstrip GND - 로 인해 TEM

Planar Transmission Line 3. planar transmission line a. Microstrip GND - 로 인해 TEM mode 가 존재하지 않으나 quasi-TEM mode로 approximation Via connection b. Coplanar Wave Guide (CPW) ( ( s ( ( GND c. Coplanar Strip (CPS) GND - GND가 표면에 있으므로 shunt connection 용이 - transmission line 구조가 넓은 면적 차지 d. Slot - line GND ( GND • S. N. U. EE (c, d : antenna-feed에 주로 사용) Microwave Devices 2008

Microstrip Transmission Line q Microstrip transmission line < dielectric의 종류에 따라 결정 > (loss

Microstrip Transmission Line q Microstrip transmission line < dielectric의 종류에 따라 결정 > (loss tangent) h dielectric GND ZO = = 50 의 경우 w 1. compact한 구조 가능, loss 증가 2. w가 너무 작은 경우 공정 제어 문제 glass substrate MIC - 미국 M/A–COM 사의 low cost 기술, 0. 7 ~ 4. 2 GHz 대역에 응용 - borosilicate glass 를 기판으로 사용 Si. O 2 substrate MIC : 텔레퍼스 (KAIST venture) – cost problem 습식 에칭 porous Si conducting Si • S. N. U. EE 산화 공정 ~30 m Si Metal 대용 conducting Si Microwave Devices 2008

Dielectrics for Microstrip Transmission Line Dielectric Loss low freq. (~10 GHz) medium freq. high

Dielectrics for Microstrip Transmission Line Dielectric Loss low freq. (~10 GHz) medium freq. high freq. (~60 GHz) Ref : Practical Microwaves, Chap. 1 • S. N. U. EE Microwave Devices 2008

FR 4 & Duroid l FR 4 for PCB (PWB) - Low Frequency Applications

FR 4 & Duroid l FR 4 for PCB (PWB) - Low Frequency Applications Alkali-free glass cloth impregnated with an epoxy resin under pressure and heat n Flame retardant properties, easily machined and die cut & very low cost n l Duroid - Higher Frequency Applications (www. rogerscorporation. com) • S. N. U. EE Microwave Devices 2008

PCB Substrate – FR 4 • S. N. U. EE Microwave Devices 2008

PCB Substrate – FR 4 • S. N. U. EE Microwave Devices 2008

Materials for MCM-L Material Comparison $ per 18 x 24 core Added Process $

Materials for MCM-L Material Comparison $ per 18 x 24 core Added Process $ FR 4 $4 -6 (1. 0 x) 1. 0 x FR 5 (Hi Tg FR 4: FR 406, etc) $5 -7 ( 1. 1 -1. 2 x) 1. 0 -1. 1 x FR 408 $7 -11 (1. 7 -1. 8 x) 1. 1 -1. 3 x Ro 3003 $28 -35 (4. 5 -6 x) 2. 5 -3. 0 x Ro 4350 $24 -30 (3. 5 -5 x) 2. 0 -3. 0 x • S. N. U. EE Microwave Devices 2008

Relative Raw Material Cost Multiplier Thin Film Cost LTCC & Photo Thick Film Polymer

Relative Raw Material Cost Multiplier Thin Film Cost LTCC & Photo Thick Film Polymer Performance • S. N. U. EE Microwave Devices 2008

Various PCB Materials Substrate material ~ 50 m • S. N. U. EE Microwave

Various PCB Materials Substrate material ~ 50 m • S. N. U. EE Microwave Devices 2008

50 Microstrip Attenuation 2. 0 Multilayer Thick Film Attenuation (d. B/Inch) 1. 5 FR-4

50 Microstrip Attenuation 2. 0 Multilayer Thick Film Attenuation (d. B/Inch) 1. 5 FR-4 Advanced PWB 1. 0 LTCC Thick & Thin Film on Alumina 0. 5 PTFE PWB (wide lines) 0 0 4 8 12 16 20 Frequency, (GHz) • S. N. U. EE Microwave Devices 2008

Microstrip Analysis (1) q Microstrip Analysis w - pure TEM mode 존재 안함 -

Microstrip Analysis (1) q Microstrip Analysis w - pure TEM mode 존재 안함 - full wave analysis h - low freq. 경우: TEM mode로 가정하여 해석 – quasi-TEM analysis - 2 =0 L, C 계산 (substrate) (air) Ca, La C, L= La air (1 st estimate q = ½ , correction q > ½ ) • S. N. U. EE Microwave Devices 2008

Microstrip Analysis (2) w (q 1) : 기판 ( r) 에 대부분 field 분포.

Microstrip Analysis (2) w (q 1) : 기판 ( r) 에 대부분 field 분포. high frequency ( w/ ) ( q 1 ) : q (f) : function of frequency (frequency dispersion) Dispersion diagram air ( /c ) d quasi-TEM analysis • S. N. U. EE freq. dispersion의 영향이 심각해지는 frequency Microwave Devices 2008

Microstrip Analysis(3) • freq. dispersion이 중요한 영역: where fd : GHz, h : cm

Microstrip Analysis(3) • freq. dispersion이 중요한 영역: where fd : GHz, h : cm • low frequency에서는 quasi-TEM approximation where = h for w > h/2 2 w for 2 t < w < h/ w ( t : metal thickness, weff : equivalent metal width ) • conformal mapping 에 의한 microstrip 해석 – ”Foundation for Microwave Engineering”, R. E Collin • S. N. U. EE Microwave Devices 2008

Characteristic Impedance of Microstrip • S. N. U. EE Microwave Devices 2008

Characteristic Impedance of Microstrip • S. N. U. EE Microwave Devices 2008

Microstrip for Ga. As MMIC Ø microstrip on Ga. As substrate – w/h ~

Microstrip for Ga. As MMIC Ø microstrip on Ga. As substrate – w/h ~ 0. 8 일때 ( r = 12) w Zo 50 Ga. As ( r ~12) 100 m (h) fd ~ 10 GHz ---- fd를 높이기 위해 h 필요 ( -strip based 광대역 증폭기 MMIC GND freq. dispersion 효과 발생이 가능) – h가 작을 경우 fragile , thermal conduction 증가 - Ga. As wafer의 초기 두께 ~ 600 m - 1000 m 표면 process 후에 backside lapping에 의한 wafer thinning - h : 25 ~100 m in microstrip MMIC ( ~25 m : power MMIC에서 사용 ) - w/h 0. 8 for Zo=50 : h, w 가 작을 경우 line 저항 증가 transmission line 의 conductor loss 증가 • S. N. U. EE Microwave Devices 2008

Higher Order Modes in Microstrip w - fundamental mode – HEO mode - transverse

Higher Order Modes in Microstrip w - fundamental mode – HEO mode - transverse resonant mode – HE 1 mode E GHz E where w , h in inches (HE 1 mode) • h = 100 m, ZO=50 f. T 200 GHz • h = 100 m, f. T= 94 GHz w = 16 mil , ZO = 18 - Zo, min 결정 : higher order mode excitation ZO가 작아지면 high freq. 까지 사용못함. - 상용 microwave CAD tool : r, eff(f) , ZO(f) 포함 full- wave analysis결과를 curve-fitting한 eq. 사용 (Ref. K. C. Gupta, pp. 102~109) • S. N. U. EE Microwave Devices 2008

Modified Microstrip Lines (1) Ø microstrip 의 변형된 형태 1. thin –film microstrip w

Modified Microstrip Lines (1) Ø microstrip 의 변형된 형태 1. thin –film microstrip w h signal dielectric GND substrate ( small h : 2 10 m ) small h small w for constant ZO , compact MMIC (NTT) too small w excessive conductance loss ( c) 이 경우 dielectric 의 r 을 감소시켜 w를 증가 c * small r dielectric : BCB ( r =2. 6), air ( r =1) • S. N. U. EE Microwave Devices 2008

Modified Microstrip Lines (2) 2. Air-filled microstrip X -ray lithography 용 mask 제작과 동일한

Modified Microstrip Lines (2) 2. Air-filled microstrip X -ray lithography 용 mask 제작과 동일한 process stress • stress control 이 중요함 Etching에 의한 Si (yield problem) thin dielectric (Si 3 N 4 , 수천 Å) Air Gap • U. Michigan 의 Prof. Katehi Si 기판 * metal cover Si Si Air Gap Si Si gap 3 h 일때 thin membrane 효과 없음 h Air Gap ( membrane coaxial cable) • S. N. U. EE Microwave Devices 2008

Microwave Packages • hermetic package -- high frequency 용 • package용 case cover air

Microwave Packages • hermetic package -- high frequency 용 • package용 case cover air Air Gap MMIC chip Si Metal cover soldering MMIC 접착제 substrate (ceramic or Si) (Micro machined Si의 package에의 응용) ceramic * plastic package -- low frequency 용 (up to 수 GHz) Ref. “Novel Micromachined Approach”, 1996. MTT-S p. 1145 • S. N. U. EE Microwave Devices 2008