This note describes the S-Parameter measurement of the MGF0915A Power GaAs FET using

Transcription

1 This note describes the S-Parameter measurement of the MGF915A Power GaAs FET using the Mitsubishi D-Case Application Breadboard. A bias network is established which is Transparent to the RF input and output over the band of interest (See Mitsubishi Bias Application note). The device is measured using a VNA with opposite sex cable ends. An output SMA adaptor is used between the Application Circuit and the cable end. The measured S-Parameters are then mathematically corrected for Adaptor [S] matrix and the electrical model for the D-Case Application Circuit board using State Of The Art circuit simulation software. MGF915A Measured Using The D-Case included in measurement Vgs (-2.5v) Ids (+1v 5Ma) The electrical Equivalent Circuit For The SMA VNA Adaptor COAX COAX ID= CX2 Di= 47 mil Di= 47 mil Do= Da mil Do= Da mil L= L4 mil L= L4 mil IND IND ER= 2.5 ER= 2.5 ID= L3 P= 1 ID= L1 TAND= Dk TAND= Dk L= L3 nh L= L2 nh RHO= Cu RHO= Cu 1 Barrel Adaptor included in measurement Cu=1.19 Dk=.234 L1=.13 L2=.527 L3=.16 Cj= C= Cj pf L4= 325 Da=149 This is the equalvalent of the epoxy capture Note: Most VNA s provide for Delay settings to establish reference measurement planes. This does not negate the reactive and loss effects of the either the Adaptor or the Application Circuit

2 The electrical equivalent for input and output of the Mitsubishi D-Case Application Test PCB COAXI2 Z= Zc L= 343 mil K= 2.3 P= 1 A=.833 F=.1 GHz ID= TL1 L= 267 mil ID= C2 C= 1 pf ID= TL3 L= L1 mil C= Ca pf Wa=47.6 L1=626 Zc=47.9 Ca=.2835 MSUB Er= 4 H= 28 mil T= 1.4 mil Rho=.7 Tand=.147 ErNom= 2.2 Name= GeTek1 -Vgs +VDS The [S] Parameter measurement correction for adaptor and Application Circuit PCB P= 1 (-) SUBCKT ID= S1 NET= Measured[S] NEG2 ID= N2 NET= ApplicationEquivalentCircuit NEG2 NEG2 ID= N3 ID= N1 NET= ApplicationEquivalentCircuit NET= Adaptor (-) 2 (-)1 Note: Simulation and correction software provided by Applied Research Microwave Office.

3 The corrected S11 and S22 are plotted for the MGF915A biased at a level of 1v 5Ma. The range over which the measurements are valid are set by the biasing circuit. The low frequency and high frequency resonances for the bias circuit are visible at both the high and low end of both input and output locus GHz GHz InputOutputZ Swp Max 6GHz The high frequency bias circuit parallel resonance S The range over which the S-Parameter measurements are valid S11 2GHz The low frequency bias circuit parallel resonance Swp Min 1GHz The measured and corrected S21db are plotted for the MGF915A biased at a level of 1v 5Ma. The bias elements are seen to be only semi transparent over a very narrow bandwidth. Further correction to include the actual bias circuits will result in greater accuracy InsertionGain The Corrected Measured S21db The Raw Measured S21db

4 The correction process can be extended an additional step to include the bias circuit Transparency Error. Reference Mitsubishi Bias Note. The 85 size bias coil is modeled as a high impedance line with slow axial phase velocity. The circuit is measured on the VNA with the MGF915A device removed. The model parameters are then optimized to match the S11 measurements data. The circuit includes the long open line to the DUT. The S11 phase and amplitude are error are minimized over the band of interest (2GHz to 4GHz) COAXI2 Z= Zc L= 343 mil K= 2.3 P= 1 A=.833 F=.1 GHz ID= TL1 L= 267 mil ID= C2 C= 1 pf BiasNetworkPhase Optimized 1-Port Equivalent circuit of the Application PCB and Bias Elements ID= TL4 L= L1 mil 1-Port S11 VNA Measurement C= Ca pf Wa=47.6 L1=626 Zc=47.9 Ca=.2835 TLINP ID= TL3 Z= 222 Ohm L= 6 mil Eeff= 1 Loss= 4 F= 2 GHz Q ID= C3 Q= C= 11 pf 95 FQ= 1 GHz ALPH= 1. The Bias Network measured in the with the DUT removed MSUB Er= 4 H= 28 mil T= 1.4 mil Rho=.7 Tand=.271 ErNom= 2.2 Name= GeTek1 VIA ID= V1 D= 2 mil H= 29.6 mil T= mil RHO= BiasNetworkLoss S11db Circuit Model S11db VNA measurement

5 The Full S-Parameter correction measurement for the MGF915A measured in the D-Case Application Circuit. and Bias Circuit correction InputOutputZ S22 with Aplication and Bias Circuit correction Swp Max 6GHz Swp Min 1GHz