Institute for Electronics Engineering Prof. Dr.-Ing. Dr.-Ing. habil. Robert Weigel

Transcription

1 Institute for Electronics Engineering Prof. Dr.-Ing. Dr.-Ing. habil. Robert Weigel Tunable BST-Varactor-Based Matching Networks for Mobile Radio Applications Errikos Lourandakis, Matthias Schmidt, Robert Weigel 1

2 Outline Motivation BST Thin-Film Varactors Matching Network Topologies L, Π, T, and Reflection-type Linear and Nonlinear Behaviour Measurement Results Summary 2

3 Motivation 3 Increasing number of mobile standards

4 Mismatch Conditions 4 Antenna Power amplifier

5 Antenna Mismatch Antenna Sleeve balun 5 Detuning of antenna impedance Near-field distortion

6 Ferroelectric Varactors Thin-film Low bias voltage High C value High tunability Resonances Thick-film High bias voltage Low C value Low tunability Large area 6

7 Ba x Sr (1-x) TiO 3 Crystal C BST ( U ) = 2cosh 2 3 C sinh max 1 2U U C max/ Perovskite-type crystal Ba / Sr ratio

8 Varactor Modelling 8 BVD model Mason model

9 Varactor Modelling (2) Quality Factor Q 9 Frequency (GHz)

10 Acoustic Resonances 10 Layered material stack Discrete acoustic impedances Parasitic FBAR

11 L - Matching Network PA Matching Tunable L is series LC Small matching area 11

12 L - Network Gain Fixed MN with Zin=25Ω SMD 0402 components Qc=50 Qc=25 Gain (db) 12 Losses for minor impedance variations

13 L - Matching Area Bias Simulated Measured 13 Excellent agreement Dynamically adjustable PA impedance Transducer Power Loss (db)

14 Π - Matching Network 14 High C value Suitable for low impedances Low IMD

15 Π Network Gain Qc=100 Qc=75 Gain (db) 15 Gain for significant impedance variations

16 Π Matching Area Bias Simulated Measured 16 Excellent agreement Losses increase for higher impedances Transducer Power Loss (db)

17 Assembly Parasitics Simulated with bond wires Simulated without bond wires Measured Transducer Power Loss (db) 17

18 T Matching Network 18 Low C values Suitable for high impedances High IMD

19 T Network Gain Qc=100 Qc=75 Gain (db) 19 Gain for signifficant impedance variation

20 T Matching Area Bias Simulated Measured Transducer Power Loss (db) 20 Excellent agreement Higher losses for low impedances

21 Reflection Matching Network 21 Total Smith-chart area coverage Hybrid coupler and phase shifters Large circuit dimension

22 Reflection Type Circuit 22 High Q values for varactors lead to large matching area

23 Reflection Network Gain Qc=100 Qc=75 Gain (db) 23 Gain for signifficant impedance variation

24 Reflection Matching Area Bias Simulated Measured Transducer Power Loss (db) 24 Excellent agreement Symmetric matching area

25 Varactor Nonlinearity DC bias point RF voltage swing 25 High tunability results in high IMD

26 Cascaded Capacitors Pin=20dBm 26 Smaller voltage swing for cascaded C

27 Two-Tone Setup 27 Typical 2-tone setup

28 L Linearity Γ2 Γ3 Γ1 Γ4 28

29 L Network IP3 N=5 N=10 Pin=20dBm IP3 (dbm) 29

30 Π Linearity Γ2 Γ3 Γ1 Γ4 30

31 Π Network IP3 N=2 N=5 N=8 IP3 (dbm) 31 Pin = 20 dbm

32 T Linearity Γ2 Γ3 Γ1 Γ4 32

33 T NetworkIP3 N=5 N=10 N=15 IP3 (dbm) 33 Pin = 20 dbm

34 Reflection MN Linearity Γ2 Γ3 Γ1 Γ4 34

35 Reflection MN Network IP3 N=5 N=10 Pin=20dBm IP3 (dbm) 35

36 Summary BST thin-film varactors & modelling Matching networks L-topology Π-topology T-topology Reflection-type Linear and nonlinear investigation Measurements 36

37 Thank you for your attention 37