Frequency Multiplier Development at e2v Technologies

Transcription

1 Frequency Multiplier Development at e2v Technologies Novak Farrington UK Millimetre-Wave User Group Meeting National Physical Laboratory

2 Outline Sources available Brief overview of doubler operation Design methodology Non-linear (Harmonic Balance) simulation Why How Linear simulation and optimization Modeling the chip geometry Filters, couplers, transitions etc. Combining models in a circuit simulator Progress so far

3 Available pump sources GaAs Gunn diode oscillators

4 Available pump sources e2v (Lincoln, UK) manufactures a range of GaAs Gunn diodes and associated oscillators 35GHz 125GHz Graded AlGaAs hot electron injection Power combiners also in development n + contact layer (500nm) Integral gold heatsink Au plated anode contact (>6µm) n + substrate (~10µm) n + buffer (500nm) n - transit region (1.1µm) Injector (75nm)

5 Available pump sources State-of-the-art powers for GaAs technology: 123GHz (2 nd harmonic) [1] 94GHz (Fundamental) GaAs material system allows various advantages: Tailor operational characteristics Ease of packaging and massproduction [1] N. Farrington, P. Norton, M. Carr, J. Sly, and M. Missous, A ruggedly packaged D-Band GaAs Gunn diode with hot electron injection suitable for volume manufacture. IEEE MTT-S International Microwave Symposium 2008, IMS2008, Atlanta, Georgia. June 15-20, RF Output Power (mw) GaAs fundamental InP fundamental 1 1 GaAs 2nd harmonic GaAs, InP 1, Alumina Ring, IHS 1, Alumina Ring, Diamond 1, Open Quartz, IHS 1, Open Quartz, Diamond 2, Alumina Ring, IHS 2, Quartz Ring, IHS 2, Open Quartz, Diamond 2, None, IHS 2, None, Diamond 3, Package unknown 3, None, IHS 1 1 denotes e2v technologies result with hot-electron injection InP 2nd harmonic Frequency (GHz) 1 Novak E. S. Farrington, e2v technologies, Lincoln, UK, September 2009

6 Frequency Doubler Operation Doubler configuration and design methodology used

7 Frequency doubler operation General multiplier schematic: Balanced configuration isolates output and input eliminating need for lossy filters Only even-order harmonics generated Multiple diodes can be incorporated into circuit to increase power handling

8 Frequency doubler configuration used Balanced doubler design chosen Variants currently being designed: 1) Cross-waveguide coupler for broadband operation below 140GHz 2) Microstrip probe-coupled output for relaxation of machining tolerances and higher frequency operation PROPRIETARY IMAGES REMOVED

9 Frequency Doubler Design Methodology Identify operational frequency and power requirements Select suitable diode chip Use HB simulator to find optimum embedding impedances (MWO) Model and simulate diode chip mount and other components (HFSS) Tune input and output matching using MWO or Ansoft Designer Non-linear circuit analysis (Harmonic Balance) Diode Impedance Linear circuit simulations (MWO) Circuit tuning Input impedance Diode mount impedance Power balance between diodes Linear electromagnetic structure simulations (FEM, HFSS) Generalized n- port s-matrix

10 Non-Linear Circuit Analysis Harmonic Balance Simulation

11 Harmonic Balance Simulations why? Increase accuracy in embedding impedance calculations Especially for resistive (real) impedance component Calculate maximum theoretical conversion efficiency and power Study variation in conversion efficiency with embedding impedance Establish change in output power, conversion efficiency, and device Q with variation in input power, frequency, and bias voltage Can be used to study the effects of chip parasitics on maximum theoretical efficiency

12 Harmonic Balance Simulations Swept variable surface plots obtained at e2v technologies using developed Harmonic Balance simulator Used to establish stable operating regions Output Power (mw) Xin Rin Conversion Efficiency (%) Xout Rout 25 30

13 Linear EM Structure Simulations HFSS and AWR Microwave Office

14 Varactor Chip Waveguide Mount Modelling Model of diode array chip mounted in the waveguide:

15 Integration of modelling results Ansoft Designer used: Dynamic links to HFSS models Allows fast tuning of electrical lengths Accurate prediction of overall module performance including sensitivity to changes in operating conditions Step to reduced height input line Input port PNUM=1 Reduced height input waveguide optimise length Mounted diode array chip Port1:1 Port2:1 Port2:1_1 Port2:1_2 Machined backshort 1:1 1:1_1 1:1_2 1:1 2:1 Anode1:1 Anode2:1 Anode3:1 Anode4:1 Anode5:1 Anode6:1 Port2 Port3 Port4 Port5 Port6 Port7 Anode ports Reduced height backshort waveguide optimise length

16 Output Circuit Modelling Required components designed for 125GHz and 140GHz modules Ansoft Corporation XY Plot 1 HammerHeadFilter140GHz Curve Info db(s(waveport2,waveport1)) Setup1 : Sw eep1 StripWidth='30um' IMAGES REMOVED d B ( S ( W a v e P o r t 2, W a v e P o r t 1 ) ) Freq [GHz]

17 Conclusions All required basic building blocks simulated in HFSS Harmonic Balance simulation technique applied and verified through comparison with published results Split block designed and fabricated for first multiplier module Quartz-based circuit in final design stages IMAGE REMOVED

18 Conclusions Thank you for your attention!!