Micromachined microwave circuits at Birmingham. M J Lancaster P S Hall, P Gardner, F Huang, Y Wang, M Ke K Jiang, P Prewett

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1 Micromachined microwave circuits at Birmingham M J Lancaster P S Hall, P Gardner, F Huang, Y Wang, M Ke K Jiang, P Prewett Department of Electronic, Electrical and Computer Engineering and Department of Mechanical Engineering The University of Birmingham 1

2 Micromachining work at Birmingham THE UNIVERSITY MEMS Switch Membrane filters MEMS with Superconductors Waveguide and coaxial cable structures We have a lot of other work at Birmingham in other microwave areas eg superconductors, antennas, amplifiers, ferroelectrics,... 2

3 Waveguide and coaxial cable structures EPSRC grant EP/D59933/1 Micromachined microwave circuits to examine alternatives Are current fabrication techniques good enough for high frequency waveguides and transmission lines? Are current fabrication techniques cost effective for complex high frequency systems? Examine:SU8 resist, Micromachined Silicon, Electroformed structures 3

4 Antenna Array Beam forming Systems Frequencies of interest 4-325GHz Antenna Array Transmission lines Micromachined beam forming network (Butler Matrix) Beam outputs Transmission lines Micromachined beam forming network (switched phased array) Beam output Phase Filters Filter control Filter Transmission lines/waveguides Couplers Filters Antennas Switch Switches Switch Switch Switch Rx Rx Rx Tx Tx Tx (a) (b) (c) 4

5 Measurement equipment THE UNIVERSITY # Model Frequency Adapters Calibration # 1 Agilent E8362B 1 MHz 2 GHz 2 HP8722ES 5 MHz 4 GHz 3 Agilent N525A PNA system 4 + OML mmhead WR5 5 + OML mmhead WR3 1 MHz 11 GHz 14 GHz 22 GHz 22 GHz 325 GHz Coax, Probe, Waveguide Coax, Probe, Waveguide Coax, Probe, Waveguide Waveguide * Waveguide * 7mm (18G), 3.5mm (26.5G), 3.5mm E- cal (9G); GSG (up to 4G), GS; WR-9 ( G). 7mm (18G), 3.5mm (26.5G); Cryogenic GSG (up to 4 G); WR-9 ( G) 2.4mm (5G), 1.mm (11G); GSG (up to 11G), GS, GSGGSG (67G); WR-1 (75-11G). WR-5 (14-22G) WR-3 (22-325G) * Coplanar probes at these frequencies are commercially available. # GSG: ground-signal-ground coplanar probe; GS: ground-signal probe; GSGGSG: dual-probe for 4-port measurements. 5

6 Transmission line Layer 1 Layer 2 Layer 3 Layer 4 Metal coated SU8 or Silicon Layer 5 Round coaxial cable Square coaxial cable waveguide Size of inner conductors from around 3 micron to 1mm. Stubs to hold up inner conductors 6

7 Simple wideband coaxial filter 7

8 Gold coated SU8 Short circuit stub Transmission line Coplanar probe input View of layer 3 with layer 2 below it Fully constructed device 8

9 measured min IL=.47dB -1-1 S11 (db) -3-4 Measurements Simulations -3-4 S21 (db) -5 SU8 layer=2um, -5 ACP11-C 15um probes Frequency (GHz) 9

10 Nickel electroplated Square coax ( using SU8 as a mould) S11 (db) Ni-Au, 3um, 38GHz with bend S21 (db) Frequency (GHz) Si Deep Dry Etched Square Coax S11 (db) S21 (db) -35 Si-Au, 2um layers Frequency (GHz) The Emerging Device Technology Portfolio Research Partnership Centre Electronic, - University Electrical of Birmingham and Computer Engineering - University of Birmingham 11

11 77 GHz Resonant Cavities in etched silicon Reosntor 1 f=77.282ghz, IL=-14.59dB, QL=456, Qu=569 Resonator 2 f=77.79ghz, IL= dB, QL=394, Qu= S21 (db) S21 (db) external coupling structure -1 external coupling structure Frequency (GHz) external coupling structure -1 external coupling structure Frequency (GHz) Measured unloaded Q = 569 and 464 Two 77 GHz cavities of different feeding structures for external coupling 11

12 Wideband rectangular coaxial couplers THE UNIVERSITY S (db) S31 S42 Simu_S31 S21 S43 Simu_S21 S41 S32 Simu_S Frequency (GHz) This coaxial line branch-line coupler is made of five bonded layers of gold-plated silicon slices, structured by deep reactive etching. The coupler shows an measured insertion loss of dB between GHz. 12

13 Butler Matrix with Antenna Array THE UNIVERSITY The figures show a proposed 4x4 butler matrix with antenna arrays, and the simulated radiation patterns. This device is used to steer antenna beams. Radiation efficiency, antenna gain. 13

14 3 μm 9636 μm MICROMACHINED COAXIAL TO RIDGE WAVEGUIDE TRANSITION Cross Sections at A, B, C, and D Layer 5 A : Coaxial Line B : Stub C : Ridged waveguide D : Transition Layer 4 Layer 3 Layer 2 A B C D Layer 1 14

15 Micromachined 3 GHz waveguide band limited power splitter. Currently being constructed 15

16 Summary Coaxial cable basic elements constructed and tested Moving on to integrate the components into filters and Butler matrix Higher frequency components being developed 16