Reconfigurable Front-End Modules Based on Ferroelectric Varactors

Transcription

1 Reconfigurable Front-End Modules Based on Ferroelectric Varactors R. Weigel and E. Lourandakis Institute for Electronics Engineering, University Erlangen-Nuremberg Cauerstraße 9, Erlangen, Germany

2 Outline Motivation Tunable Passive Components Part 1 Frequency Agile Filters Frequency Agile Power Dividers & Couplers Prototype Implementation & Results Part 2 Impedance Matching Networks L, Pi, T, and reflection type Prototype Implementation & Results Conclusion

3 Motivation Increasing number of communication bands Additional wireless services, e.g. GPS, WiMAX Demand for reconfigurable front-end solutions

4 Ferroelectric Thin-Film Varactors Nonlinear component Compact dimensions Induced acoustic resonance

5 Ferroelectric Thin-Film Varactors zero bias Metal-Insulator-Metal (MIM) Compact dimensions Q around 2 GHz ADS model available bias 20V

6 Filter Design Lowpass Chebyshev lowpass filter Analytical formulas for zero locations

7 Filter Design Notch Filter Notch filter Analytical formulas for zero and pole locations zero pole

8 Modified Combline Filter Combline Modified Second attenuation pole is shifted from DC to lower stopband

9 Frequency Agile λ/4 Segments Tuning of C eq shifts resonance Scalable network Slightly detuned Z Perfect phase shift

10 Tunable Wilkinson Divider Wilkinson Modified equivalent lowpass Size reduction 50% Multiband tuning Assumed tunability 60%

11 Tunable Branch-Line Coupler equivalent lowpass Branch-Line Modified Size reduction 50% Perfect phase match C eq serves as shunt element for both segments

12 Tunable Branch-Line Coupler equivalent lowpass Size reduction 50% Perfect phase shift Multiband operation with tunability of 60% for C eq

13 Tunable Lowpass (1) Biasing elements Tuning range of 30% 1.5-2GHz multiband High losses due to moderate Q and RF isolation

14 Tunable Lowpass (2) Biasing Good agreement Loss due to varactor imbalances and prototype assembly Two-tone 1.95GHz with Δf=5MHz and Bias=20V

15 Tunable Notch Filter (1) RF-choke Cascaded varactors simplify biasing Notch tuning GHz Multiband operation Low losses S 21

16 Tunable Notch Filter (2) RF-choke Good agreement between simulation and measurement Two-tone 1.95GHz with Δf=5MHz and Bias=20V

17 Tunable Combline Filter (1) Good agreement Compact dimensions IL < 3dB and RL > 20dB Tuning 1.8-2GHz

18 Tunable Combline Filter (2) Two-tone with Δf=5MHz and Bias=5V OIP3=36.5dBm

19 Tunable Wilkinson Divider (1)

20 Tunable Wilkinson Divider (2) IL < 1.2dB, Isolation > 25dB Lowpass filtering S 21,S 31 Attenuation > 20dB at 2f 0 Tuning range GHz

21 Tunable Branch-Line (1) Size reduction 50% Lowpass filtering Attenuation > 30dB at second harmonic V Bias =5V

22 Tunable Branch-Line (2) V Bias =9V V Bias =15V

23 Tunable Branch-Line (3) Tuning range GHz IL < 2.7dB, RL > 15dB Amplitude error < 0.4dB, phase error < 5deg

24 Part 2 Impedance Matching Motivation - Missmatch Conditions L Matching Network Pi Matching Network T Matching Network Reflection Type Matching Network

25 Mismatch Conditions Antenna Power amplifier

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

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

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

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

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

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

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

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

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

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

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

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

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

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

40 Conclusion Conclusion Potential of ferroelectrics in tunable front-end Tunable microwave circuits Prototype implementation & results Outlook Integration of tunable microwave subsystems in front-end architectures