Welcome. Andy Howard Senior Applications Engineer Agilent EEsof

Transcription

1 Welcome Andy Howard Senior Applications Engineer Agilent EEsof 1

2 Outline What is load pull and why do it? Working with measured load pull data use to design matching networks Simulating load pull on nonlinear device models (including X-Parameters) use to determine optimal source and load impedances 2

3 Outline What is load pull and why do it? Working with measured load pull data use to design matching networks Simulating load pull on nonlinear device models (including X- Parameters) use to determine optimal source and load impedances 3

4 A really simple load pull 4

5 Device performance depends on source and load impedances f1 f2 f3 freq External source (or previous stage) Input match. network Output match. network f1 f2 f3 freq External load (or next stage) 5

6 Fundamental load pull setup Why? Quick sanity check ; adjust sampled area f1 f2 f3 freq Source tuner Available source power constant f1 f2 f3 freq Load tuner Guess reasonable values for all variables. Adjust, if necessary. 6

7 Fundamental load pull with power sweep Why? See gain compression and constant power delivered data f1 f2 f3 freq Source tuner Load tuner Available source power swept freq f1 f2 f3 freq 7

8 Fundamental source pull setup Why? Source impedances affect performances, too f1 f2 f3 freq Source tuner Available source power constant f1 f2 f3 Load tuner freq 8

9 Fundamental load pull with parameter sweep Sweep any parameter - source frequency, bias, etc. Why? Investigate device performance more thoroughly f1 f2 f3 freq Source tuner Load tuner Available source power constant freq f1 f2 f3 freq 9

10 Harmonic load phase sweep Why? Harmonic impedances matter, but usually want high reflection f1 f2 f3 freq Source tuner Load tuner Sweep input power to see constant power delivered data freq f1 f2 f3 freq 10

11 Source stimulus determines responses we may plot IMD from 2-tone source ACLR from modulated source Gain comp. curves from source power sweep 11

12 Constant power delivered load pull with parameter sweep more precise characterization Sweep any parameter - source frequency, bias, etc. f1 f2 f3 freq Source tuner Load tuner Power delivered held constant via optimization Available source power optimized freq f1 f2 f3 freq 12

13 Check sensitivity of completed design f1 f2 f3 freq Source tuner Input match. network Output match. network Could be X-Parameter model, instead Load tuner f1 f2 f3 freq 13

14 Outline What is load pull and why do it? Working with measured load pull data use to design matching networks Simulating load pull on nonlinear device models (including X- Parameters) use to determine optimal source and load impedances 14

15 You have measured load pull data (Maury) 15

16 What s the optimal load? What performance can we get from this device? 16

17 Examine performance contours 1) Reads LP data file 2) Simulates S-parameters of network 3) Gets corresponding performance data Tuner generates loads in region you specify 17

18 View independent variables and performance parameters Frequency and input power constant 18

19 Plot performance contours of interest Load giving best performance 19

20 Using measured data containing a power sweep Why sweep power? See gain compression data. Sweep values within range of those in file Sweep based on gamma_x, gamma_y values in file 20

21 Contours at specified gain compression Why do contours look strange? Measurements at some loads were not valid. 21

22 Contours at a particular input power 22

23 From contours we decide optimal impedances. What s next? Design impedance matching network(s) using existing techniques, or 23

24 Use measured data directly in optimization This impedance should be the same as this. 24

25 Optimized component values and corresponding reflection coefficient 25

26 Outline What is load pull and why do it? Working with measured load pull data use to design matching networks Simulating load pull on nonlinear device models (including X- Parameters) use to determine optimal source and load impedances 26

27 A sequence for running load pull simulations 1) 1-tone, 1 input power load pull 2) Add power sweep to see gain compression 3) Run frequency or bias sweep 4) Run harmonic load phase sweep 5) Run constant output power with swept var 6) Run source pull 7) Use 2-tones to see IMD 8) Use modulated signal to see ACLR Based on experience: a) Change order b) Delete steps c) Iterate 27

28 Use of instrument subcircuits simplifies setup Most parameters are passed to tuner inside instrument subcircuit 28

29 Start with fast, simple load pull Available source power held constant Guess optimal Zsource and harmonic Zs Refine sample space Source Power = 5 dbm Source Power = 12 dbm 29

30 A sequence for running load pull simulations 1) 1-tone, 1 input power load pull 2) Add power sweep to see gain compression 3) Run frequency or bias sweep 4) Run harmonic load phase sweep 5) Run constant output power with swept var 6) Run source pull 7) Use 2-tones to see IMD 8) Use modulated signal to see ACLR Based on experience: a) Change order b) Delete steps c) Iterate 30

31 Load Pull with power sweep 31

32 Interpolated data at 30 dbm output power 32

33 Loads for maximum PAE and minimum gain compression 33

34 Contours at X-dB gain compression 34

35 Adjusting contour lines to all pass through maximum PAE load Maximum PAE (Perf1 marker) occurs with 28.8 dbm power delivered (Perf3 contour) and 12.3 db gain (Perf2 contour.) 35

36 A sequence for running load pull simulations 1) 1-tone, 1 input power load pull 2) Add power sweep to see gain compression 3) Run frequency or bias sweep 4) Run harmonic load phase sweep 5) Run constant output power with swept var 6) Run source pull 7) Use 2-tones to see IMD 8) Use modulated signal to see ACLR Based on experience: a) Change order b) Delete steps c) Iterate 36

37 Contours versus swept parameter (frequency) 28 dbm contour at 750 MHz 28 dbm contour at 1.25 GHz 37

38 A sequence for running load pull simulations 1) 1-tone, 1 input power load pull 2) Add power sweep to see gain compression 3) Run frequency or bias sweep 4) Run harmonic load phase sweep 5) Run constant output power with swept var 6) Run source pull 7) Use 2-tones to see IMD 8) Use modulated signal to see ACLR Based on experience: a) Change order b) Delete steps c) Iterate 38

39 Dependency on phase of gamma at harmonic(s) 39

40 A sequence for running load pull simulations 1) 1-tone, 1 input power load pull 2) Add power sweep to see gain compression 3) Run frequency or bias sweep 4) Run harmonic load phase sweep 5) Run constant output power with swept var 6) Run source pull 7) Use 2-tones to see IMD 8) Use modulated signal to see ACLR Based on experience: a) Change order b) Delete steps c) Iterate 40

41 Also sweeping gate bias Controlling output power enables more precise analysis 41

42 Contours with gate bias = 1.5 V 42

43 High PAE, but low gain 43

44 Results with gate bias = 2.25 V 44

45 A sequence for running load pull simulations 1) 1-tone, 1 input power load pull 2) Add power sweep to see gain compression 3) Run frequency or bias sweep 4) Run harmonic load phase sweep 5) Run constant output power with swept var 6) Run source pull 7) Use 2-tones to see IMD 8) Use modulated signal to see ACLR Based on experience: a) Change order b) Delete steps c) Iterate 45

46 Constant power delivered load pull with two tones 46

47 A sequence for running load pull simulations 1) 1-tone, 1 input power load pull 2) Add power sweep to see gain compression 3) Run frequency or bias sweep 4) Run harmonic load phase sweep 5) Run constant output power with swept var 6) Run source pull 7) Use 2-tones to see IMD 8) Use modulated signal to see ACLR Based on experience: a) Change order b) Delete steps c) Iterate 47

48 Load pull with WCDMA signal Read modulated data from file. Scale signal amplitude by optimizing SFexp variable. 48

49 Review Basic load pull concepts Using measured load pull data files to design matching networks Fast, simple load pull Adding power sweeps to see compression Sweeping frequency Sweeping harmonic reflection coefficient phase Constant power-delivered load pull with sweep Using two tones to see intermodulation distortion Load pull with a WCDMA source 49

50 For more information: On the latest release of ADS: On the latest release of the ADS Load Pull DesignGuide: Load+Pull+DesignGuide+Enhancements+for+post+ADS+2011_05 50

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