Case Study Amp2: Wideband Amplifier Design. Case Study: Amp2 Wideband Amplifier Design Using the Negative Image Model.

Transcription

1 MICROWAVE AND RF DEIGN Case tudy: Amp Wideband Amplifier Design Using the Negative Image Model Presented by Michael teer Reading: Chapter 18, ection 18. Index: CAmp Based on material in Microwave and RF Design: A ystems Approach, nd Edition, by Michael teer. citech Publishing, 013. Presentation copyright Michael teer Case tudy Amp: Wideband Amplifier Design Design of an 8 1 GHz hjfet Amplifier with 1 db gain RF IN Port 1 lides copyright 013 M. teer. RF OUT hjfet Port 1 tarting Point pecifications 8 1 GHz 1 ± 1 db gain. This is transducer gain: Maximum noise figure of 1 db Topology 3

2 11, 1, 11, 1,, GHz 0.1 GHz 0.1 GHz GHz in Input matching network a 1 b 1 1 a b L Approximate Input Matching Network B 1 GHz 1 = * in for optimum M1. Curve B is approximate optimum. 0.1 GHz 1 in 1 L = L 1 is small so in is close to 11. We want small so = * in for maximum power transfer (optimum M1) GHz A 6 7

3 Case tudy: Wideband Amplifier Design Using the Negative Image Model. Part B, Image Model ve ve ve Design approach preview B 1 GHz for optimum M1. What does this look like? A resistor and negative capacitor in series. 8 Looking ahead: amplifier design using a negative image model Looking ahead: amplifier design using a negative image model R $ ( C) ve ve ve ve 9 10

4 Case tudy: Wideband Amplifier Design Using the Negative Image Model. Part C, Gain OURCE Gains AVAILABLE ACTUAL DEVICE AVAILABLE DEVICE AVAILABLE INPUT IGNAL INPUT IGNAL OUTPUT IGNAL OUTPUT IGNAL POWER POWER POWER POWER P Ai P in D P ADo P Ao M M INPUT 1 ACTIVE OUTPUT MATCHING DEVICE MATCHING NETWORK NETWORK LOAD OURCE AVAILABLE ACTUAL DEVICE AVAILABLE DEVICE AVAILABLE INPUT IGNAL INPUT IGNAL OUTPUT IGNAL OUTPUT IGNAL POWER POWER POWER POWER P Ai P in D P ADo P Ao P in M M INPUT 1 ACTIVE OUTPUT MATCHING DEVICE MATCHING NETWORK NETWORK P L LOAD P in Transducer Gain Maximum Available Power Gain 1 GMA k k k 1 1 G T with optimum M 1 and M P L Maximum table Gain G M 1 1 Like G MA at edge of stability k = Transistor properties G MA is undefined from 8 to 1 GHz The amplifier is not unconditionally stable G db Target transducer gain is 1 db Achieved by detuning the matching networks Z M Input 1 network 1 1 Transistor Maximum table Gain G M 1 1 Like G MA at edge of stability k = 1. M Output network Z L Case tudy: Wideband Amplifier Design Using the Negative Image Model. Part D, Noise I ource Y e n i n Noiseless active device Load Z L ource 1 IN 1 Z IN OUT Z OUT L Load 1

5 Noise e n Noise I I ource ource Active Y Z Noisy amplifier model device L with noisy active device. e n Load Noiseless Noisy amplifier model Y i active Z n L with noise free active device device. Load e n and i n are partially correlated for a transistor. The source admittance determines how they combine. Noise could be minimized with right Y. I ource Y i n Noiseless active device Load Noise performance of a two port is described by NRi F noise factor F (Noise figure, NF = 10 log F). NR o r n F Fmin ys y r opt n is the equivalent noise resistance gs y s = Y / Y 0 gs { ys} y opt is the optimum value of y s Z L F min is F when y s = y opt 13 1 I Y e n i n Noise Noiseless active device Z L F F rn s opt min 1s 1opt Noise figure circles F MIN NF MIN ource r n F Fmin ys yopt gs F Load F r n opt min 1 1 s s opt Circles have increasingly higher NF

6 Noise file Noise data F F r n opt min 1 1 s s opt Frequency NF min opt r n Minimum noise figure Noise figure circles NF min on the input (Γ ) plane Minimum noise figure, NF min. 1 GHz 7 GHz Noise figure circles at 10 GHz where NF min = 0.5 db. NF MIN NF min = 0.38 db, 0.1 db, 0.3 db, 0.7 db, 0.50 db, 0.55 db, 0.60 db, 0.66 db and 0.71 db from 7 to 1 GHz in 1 GHz steps. Circles have 0.1 db steps so that the inner most circle indicates the values of Γ that achieves NF = 0.6 db. 19 0

7 0.5 db noise figure circles. The noise figure on each circle is NF min db. At 10 GHz circle is for NF = 0.75 db Noise figure circles 7 GHz Noise vs. Input match B NF min 1 GHz 1 GHz 0.1 GHz 0.1 GHz plane 7 GHz cf specification is for NF 1 db 11 1 GHz A Curve B is approximately the optimum for maximum gain. Points indicate optimum for minimum noise figure. 1 plane 11 * Noise vs. Input match 1 GHz 7 GHz NF min ummary, so far There is a reasonable trade-off between optimum input match and good noise performance. till to consider: tability Network topology that will lead to counterclockwise rotation on the mith chart

8 Case tudy: Wideband Amplifier Design Using the Negative Image Model. Part E, tability GHz steps must be in stable region. Input stability circles GHz GHz UNCONDITIONALLY TABLE 5 GHz steps Output stability circles L must be in the stable region. Noise vs. input match vs. stability plane 11 * NF min 1 GHz 7 GHz GHz GHz 6 7

9 Maximum available gain 7 GHz G MAX circles at 10 GHz in 1 db steps The central circle has G MAX =15.5 db (Recall that the target gain is 1 db) A G MAX = 17.0 db, 16.5 db, 16.0 db, 15.5 db, 15. db, 1.8 db, 1.5 db, 1.1 db at 7 to 1 GHz in 1 GHz steps. 1 GHz B C D E 8 9 ummary A tradeoff of stability, and noise and gain performance. Input matching network: 0.5 Network design using the negative image model Previously reached a tradeoff of stability, and noise and gain performance Tradeoff of stability, noise, and gain performances imilar development for output matching network

10 Case tudy: Wideband Amplifier Design Using the Negative Image Model. Part F, Image Model-Based Design Amplifier design using a negative image model ve ve ve 3 Case tudy: Wideband Amplifier Design Using the Negative Image Model. Part G, Completing the Design RF IN RF OUT Completing the amplifier design o far: Designed the input/output matching network using input image model. Design tuning of parameters. Final stage: Design real input and output matching networks independently Assemble entire amplifier Optimize design Use a few select parameters to optimize 33

11 Amplifier designed using the negative P= Z=68 Ohm image model Z=.9 Ohm C= 0.9 pf UBCKT ID= NET="N300a" Designed using tuning as there are only 5 parameters. Computer optimization could have been used. C= 0.36 pf Gain (db) IND ID=L1 L= 0.67 nh Target: 1 db gain NF < 1 db Frequency (GHz) NF (db) Design step Topology that produces counter-clockwise locus (with respect to frequency) on mith chart. Well, perhaps ust standstill Real input network design setup Z=.9 Ohm Input image model C= 0.9 pf UBCKT ID= NET="N300a" C= 0.36 pf UBCKT ID=1 NET="Input Network" 1 IND ID=L1 L= 0.67 nh C=0.9 pf P= Z=68 Ohm RE ID=R1 R=.9 Ohm Design goal preview 1 GHz Z ource 1 1 M 1 Input network 1 Transistor Z=.9 Ohm C= 0.9 pf IN 1 Z IN Now design the Input Network 36 37

12 impler design problem. Input image model UBCKT ID=1 NET="Input Network" 1 C=0.9 pf RE ID=R1 R=.9 Ohm Design approach preview 1 GHz Z ource 1 1 M 1 Input network 1 Transistor Z 0 = IN 1 Z IN Z 0 = Realization of the Input network MLIN ID=L3 W=635 um L=1000 um UBCKT ID=1 NET="Input Network" 1 MTEEX$ ID=MT MLIN ID=L1 W=600 um L=37. um C=0.9 pf MTEEX$ ID=MT1 RE ID=R1 R=.9 Ohm MLIN ID=L W=15 um L=67.1 um P= Reflection coefficient looking into input matching network in UBCKT ID=1 NET="Input Network" 1 C Transistor RE ID=R1 R in 1 GHz MUB Er=9.8 H=635 um T=6 um Rho=1.0 Tand=0.0 ErNom=9.8 Name=UB1 MLEFX ID=TL W=635 um L=1151 um MLC ID=TL1 W=15 um L=680.5 um Transistor 0 1

13 Input network reflection coefficient from transistor 1 GHz * NF min Z ource 1 1 M 1 Input network 1 Transistor IN 1 Z IN Input network reflection coefficient from transistor * NF min 3 Output image model: Output network Realization of the output network MLIN ID=L3 W=65 um L=1000 um MTEPX$ ID=M1 Offset=0 um UBCKT ID=1 NET="Output Network" 1 MLIN ID=L1 W=100 um L=358. um MTEEX$ ID=MT1 C=0.36 pf MLIN ID=L W=100 um L=538 um IND ID=L1 L=0.67 nh RE ID=R1 R=68 Ohm P= Reflection coefficient looking into output matching network UBCKT ID=1 NET="Output Network" 1 C=0.36 pf IND ID=L1 L=0.67 nh RE ID=R1 R=68 Ohm 1 GHz MUB Er=9.8 H=635 um T=6 um Rho=1.0 Tand=0.0 ErNom=9.8 Name=UB1 MLC ID=TL W=50 um L=3 um Approximately / at 10 GHz. 8GHz Output network. 5

14 o far: Final stage of design Designed the input matching network using input image model. Used tuning of parameters. Designed output matching network using input image model. Used tuning of parameters. Final stage: Assemble entire amplifier Optimize design Use a few select parameters to optimize NF (db) Gain (db) RF IN UBCKT ID= NET="Input Network" Final amplifier UBCKT ID=3 NET="Output Network" UBCKT ID= NET="N300a" Frequency (GHz) RF OUT P= RF IN pecification: 8 1 GHz 1 db gain NF < 1 db RF OUT 6 7