Presentation on theme: "BENNY SHEINMAN, DAN RITTER MICROELECTRONIC RESEARCH CENTER"— Presentation transcript:
1Monolithically Coupled Photo Diode - HBT or a Photo - HBT : A Modeled Comparison BENNY SHEINMAN, DAN RITTERMICROELECTRONIC RESEARCH CENTERELECTRICAL ENGINEERING DEPARTMENTTECHNION – ISRAEL INSTITUTE OF TECHNOLOGY
2Workshop outline Introduction. Phototransistor electrical configurations.General bandwidth / efficiency limitations in a photo-detector.Additional limitation in a top illuminated PIN diode / phototransistor.Electrical modeling of the top illuminated PIN diode / phototransistor.
10Cascode Configuration Performance comparableto that of a PIN + HBT?
11Current Density [KA/cm Current Density [KA/cm Kirk effect50100150200250Current Density [KA/cm2]Frequency [GHz]650nm CollectorFtmax50100150200250300Current Density [KA/cm2]Frequency [GHz]150nm CollectorFmaxt
12Kirk effect (cont.) Associated time constant for a 1*10 emitter and a 10 diameter optical window:
13Photodetectors bandwidth limitations Carrier transit time:RC of detector capacitance and amplifier input resistance:M. Agethen et al. IPRM 2002
29Model of top illuminated detector Solution of current equations is difficult:- distributed photocurrentPhotodiode capacitance / areaYet for a known capacitance value,a single pole fit gives good results480.2pF
33ConclusionsIn the cascode configuration, photo-HBT have comparable performance to PIN detector + HBT processed from the same layers.PIN detector + HBT processed from different layers will have superior performance.The highly resistive base layer produces an internal filter in the top illuminated PIN detector.The influence of the filter should be included in the model of the detector.