1 An X-Band Low Noise InP-HBT VCO with Separate Optimized Varactor LayersT. Magrisso (1)D. Elad (1)N. Buadana (1)S. Kraus (2)D. Cohen Elias (2)A. Gavrilov (2)S. Cohen (2)D. Ritter (2)(1) RAFAEL, Armament Development Authority Ltd., Microelectronic Directorate(2) Department of Electrical Engineering, Technion-Israel Institute of Technology
2 InP Based VCOs Record frequencies Optoelectronic integration: Optoelectronic Oscillitor,Clock recovery, etc..
3 Previous work on InP HBT circuits at Technion: 43 GHz integratedTWA photoreceiver75 GHz TWA
4 Varactors in InP HBT VCOs Previous InP HBT VCOs used base collector layersas varactor layers.Optimized HBT requires fully depleted collectorat Vbc=0, for minimum VCO’s phase noise.As a results, small tuning range is obtained
5 Conventional InP HBT technology 10um1umPNN+InP N EmitterNPGa InAs P BaseNGa InAs N CollectorN+Ga InAs N Sub-CollectorInP Semi-insulating Substrate
6 Separate varactor layers Varactors and HBTs can be separately optimized.Varactor layers can be grown either above or underneaththe transistor layers.Varactor layers underneath transistor layerscomplicate interconnect.Varactor layers above transistor layersrequire stepper technology.
7 InP HBT technology with Separate Varactor Layers InP N EmitterNGa InAs P BaseInP N CollectorN+InP N Sub-CollectorPNGa InAs P BaseInP N Varactor NN+InP N Varactor ConnectInP Semi-insulating Substrate
8 This Work Carried out by contact lithography-varactor layers underneath transistor layers.Wide tuning range Colpitts X band VCO demonstratedas first attempt.Simplified VBIC transistor model predicts wellVCO’s performance.
9 Transistor Properties Ft=180 GHzFmax=200GHzVturn-on=0.5VVce-breakdown=5VIc max (Vce=3v)=30mAβAC=50
10 Transistor Modeling DC Measurements and s-parameters Small-signal equivalent circuit parameters extraction.Degenerate VBIC model with 18 parameters only
22 Conclusions InP HBT X band VCO with separate varactor layers underneath transistor layers achieved tuning range of12% and phase noise of -94dB/Hz at 100KHz.Future work: VCO layers on top of transistor layers forhigher frequencies, and optoelectronic applications. .
23 Acknowledgement We would like to thank ….. Dr. David Rosenfeld for supporting the project.Rafael Microelectronic Direcrotate Design groupeand Testing House.Technion Russell Berrie Nanotechnology Institute.Liron Arazi and Kochavi Shemuel for design andtesting assistance.Dr. Asher Madjar.