GUC (Dr. Hany Hammad) 9/5/06 Microwave Technology (COMM 903) Contents Introduction: Course contents. Assessment. eferences. Microwave Sources. Transistor Model Extraction. Signal flow graphs. COMM (903) Lecture #
GUC (Dr. Hany Hammad) 9/5/06 Course Contents Active Microwave & F Circuits Analysis & Design Noise, Microwave Sources, Amplifiers, Mixers & Oscillators. Metamaterials and Transmission Lines Basic properties, Transmission Line Implementations and Applications. Teaching Assistant (Tutorials) En. anda El Khosht Teaching Assistant (Advanced Comm. Lab.) Eng. asmine Abdella eferences David M. Pozar, Microwave Engineering, 3rd Edition, Wiley. Lecture Notes COMM (903) Lecture #
GUC (Dr. Hany Hammad) 9/5/06 Assessment Quizzes (-3) 5 Tutorial Assignments 5 Project 0 Mid Term Examination 5 Final Examination 45 Total 00 Microwave Sources Solid State Sources Low Power & Low Frequencies Sources Microwave Tubes High Power &/or high frequencies Sources Microwave Engineering, 3rd Edition by David M. Pozar Copyright 004 John Wiley & Sons COMM (903) Lecture # 3
GUC (Dr. Hany Hammad) 9/5/06 Microwave Tubes Types of Microwave Tubes: Klystron TWT (Traveling Wave Tubes) Helix TWT. Coupled cavity TWT. Magnetron. Gyroton. Gridded Tube. CFA (crossed field amplifiers) Solid State Sources Advantages: Small Size. Low Cost. Compatibility with microwave integrated circuits. Disadvantages: Low power. Low frequencies. COMM (903) Lecture # 4
GUC (Dr. Hany Hammad) 9/5/06 Solid State Sources Can be categorized as: Two terminal devices Ex.: Diodes. Three terminal devices Ex.: Transistor oscillators. Diode Sources Most common diode sources: Gunn diode. IMPATT diode. Directly convert DC bias to F power in the frequency range of to 00 GHz. COMM (903) Lecture # 5
GUC (Dr. Hany Hammad) 9/5/06 Gunn Diode Even though everyone uses this term! It s more accurate name is a Transferred Electron Device (TED). Why isn't it a "real" diode? Because it only uses N-type semiconductor. Gunn diodes have been around since John Gunn discovered that bulk N-type GaAs can be made to have a negative resistance effect. Three regions exist: two of them are heavily N-doped on each terminal, with a thin layer of lightly doped material in between. Broadband Microwave Amplifiers by Bal S. Virdee, Avtar S. Virdee, & Ben. Banyamin Copyright 004 Artech House Gunn Diode Two Gunn diode sources. The unit on the left is a mechanically tunable E-band source, while the unit on the right is a varactor-tuned V-band source. Microwave Engineering, 3rd Edition by David M. Pozar Copyright 004 John Wiley & Sons COMM (903) Lecture # 6
GUC (Dr. Hany Hammad) 9/5/06 FET Small Signal Models COMM (903) Lecture # 7
GUC (Dr. Hany Hammad) 9/5/06 The GaAs MESFET Structure Cross sectional view of the GaAs MESFET structure shows the depletion region below the gate The contact of the gate is made of metal-semiconductor Schottky Contact rather than a metal-oxide-semiconductor (MOS) structure, which is used in the MOSFET device. This approach minimizes the device s gate to source capacitance, which otherwise would degrade the high-frequency gain performance. Broadband Microwave Amplifiers by Bal S. Virdee, Avtar S. Virdee, & Ben. Banyamin Copyright 004 Artech House The GaAs MESFET g f m T w sv h d gm C sat g m = intrinsic device transconductance h d = depletion-layer depth w = gate width s = semiconductor dielectric constant v sat = saturated carrier velocity f T = Unity-current-gain frequency C = gate to source capacitance At frequencies above f T the current passing through the C is greater than that produced by the transconductance, therefore, f T represents a fundamental high-frequency limit. C f T w l h s g g d vsat l For optimum high-frequency performance, the device designer must either increase the saturated carrier velocity or decrease the gate length. COMM (903) Lecture # 8
GUC (Dr. Hany Hammad) 9/5/06 Device Characterization and Modeling Small signal model Intrinsic & Extrinsic elements is determined using the hot and cold deembedded S-parameters measurements. Large Signal model is determined by using the semi-empirical method, and it uses the measured pulsed dc I-V data of the device and no assumptions are made relating to the physical operation of the device itself. One key issue in S-parameters measurements is the accurate calibration of the network analyzer. The calibration of the instrument should remove unwanted and repeatable information, such as the effects of non-ideal transmission lines, connectors, and circuit parasitic. Small-signal device modeling procedure Cold V ds = 0 V V = -3 V (pinch off) Broadband Microwave Amplifiers by Bal S. Virdee, Avtar S. Virdee, & Ben. Banyamin Copyright 004 Artech House COMM (903) Lecture # 9
GUC (Dr. Hany Hammad) 9/5/06 Hot S-parameters Extraction C dc = diople layer capacitance g & d represent the device s gate and drain resistance. s & L s are the source resistance and inductance. The extrinsic parameters C gp, C dp, L g, L d, g, s and d. The gate and drain bond-pad capacitance (C pg and C pd ) in the modeling process. Broadband Microwave Amplifiers by Bal S. Virdee, Avtar S. Virdee, & Ben. Banyamin Copyright 004 Artech House Cold S-parameters Extraction Broadband Microwave Amplifiers by Bal S. Virdee, Avtar S. Virdee, & Ben. Banyamin Copyright 004 Artech House COMM (903) Lecture # 0
GUC (Dr. Hany Hammad) 9/5/06 Cold S-parameters Extraction Z Z Z C c g s j Lg Ls C j c Zc s Ls C c d s j Ld Ls C C ab a b g s d e Z c e Zc e Z Z c Z b ab C c c C C C bc bc b c c Lg Ls Cab Im Z c Ls Cb c Ld Ls Cbc Im Z Im Z Hot S-parameters Extraction v + - g g m e j mo jc j g e C j mo ds i j jc ji C jc C C ds Broadband Microwave Amplifiers by Bal S. Virdee, Avtar S. Virdee, & Ben. Banyamin Copyright 004 Artech House COMM (903) Lecture #
GUC (Dr. Hany Hammad) 9/5/06 Model Extraction C Im C g Im C e Im C i mo e Im e C e Im( ) C Ci C Im e C / sin C ds Im ds e C i g mo g m g mo e j S-parameters files COMM (903) Lecture #
GUC (Dr. Hany Hammad) 9/5/06 Extraction Steps Measure the S-parameters and save as.sp file. Load file into Matlab (load file name.sp) Convert the sp to y-parameters using the equations (or using sy command in matlab. MESFET Model Extraction Project Gate I C I Drain + v C - V g m v V ds C ds i Source I V V I V V COMM (903) Lecture # 3
GUC (Dr. Hany Hammad) 9/5/06 Finding & In case of V =0 Gate I C I Drain + v C - V g m v V ds C =0 ds i Gate Source C I I Drain + v C V - g m v V =0 i Source Finding & Gate I V j C I + v C V - g m v V =0 i Source I v I V V i V jc gmv jc V jc jc jc gmv jc i i I V I V V V 0 0 jc gm jc jc i i jc COMM (903) Lecture # 4
GUC (Dr. Hany Hammad) 9/5/06 Finding & jc jc jc jc C Ci jc i jc i jc jc jc i jc i i Ci C j C D D D C i Finding & Gate I C + v C V - V g m v ds Cds i I Drain Source Gate I C I Drain V ds Source I V jc C Cds V I V V 0 V 0 ds jc ds COMM (903) Lecture # 5
GUC (Dr. Hany Hammad) 9/5/06 Extracted Model Parameters NE3000 V ds = V I d = 0 ma 4 C.5480 F 0. 0548pF 3 C.780 F 0. 78 pf i 7. 3838 g m 0.0664 S 3.590 3 sec 0.359psec 4 C ds 4.77530 F 0. 47753pF ds 98. 94 esults (Measured Vs Calculated from extracted Model) 4 x 0-3 3.5 3.5 e( ) (S).5 0.5 0.03 0.05 0 Measured Calculated -0.5 0 5 0 5 0 5 30 freq. (GHz) m( ) (S) 0.0 0.05 0.0 0.005 Measured Calculated 0 0 5 0 5 0 5 30 freq. (GHz) COMM (903) Lecture # 6
GUC (Dr. Hany Hammad) 9/5/06 esults (Measured Vs Calculated from extracted Model) 0.5 x 0-4 0-0.5 e( ) (S) - -.5 - -.5 Measured Calculated -3 0 5 0 5 0 5 30 freq. (GHz) m( ) (S) 0 x 0-3 -0.5 - -.5 - -.5-3 -3.5-4 -4.5 Measured Calculated -5 0 5 0 5 0 5 30 freq. (GHz) esults (Measured Vs Calculated from extracted Model) 0.074 0.07 0.07 e( ) (S) 0.068 0.066 0.064 0 0.06 0.06 Measured Calculated 0.058 0 5 0 5 0 5 30 freq. (GHz) m( ) (S) -0.005-0.0-0.05-0.0 Measured Calculated -0.05 0 5 0 5 0 5 30 freq. (GHz) COMM (903) Lecture # 7
GUC (Dr. Hany Hammad) 9/5/06 esults (Measured Vs Calculated from extracted Model) 5.3 x 0-3 5. 5. ( ) (S) 5 4.9 0.04 0.0 4.8 Measured Calculated 4.7 0 5 0 5 0 5 30 freq. (GHz) m( ) (S) 0.0 0.008 0.006 0.004 0.00 Measured Calculated 0 0 5 0 5 0 5 30 freq. (GHz) COMM (903) Lecture # 8