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Published byTravis Styles Modified over 10 years ago
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MTT 2002 Seattle June 5th S. K. Leong LDMOS and Vdmos 30 - 512 Mhz BroadBand Amps
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30 - 512 Mhz Broadband Amps A. 30 - 512 Multi-octave Military Amplifiers covering tactical ground, air, civil and those of allies. B. Polyfet Technical Bulletins Different Output Power and Gain 28V and 12.5V voltage supplies C. 4:1 Broadband matching Variable transformation ratio to match transistor Zin Small physical size. D. Computer Simulation results
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Polyfet Technical Bulletins
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Design Considerations Load line required by device changes with frequency Load Pull techniques not practical for high power and low frequencies. Computer simulation using Spice model is preferred. 4:1 Most practical transformer for broadband Use effective inductance of coaxial transmission line as the inductive component in the PI matching network. Keep overall physical dimension small. (A lumped 4:1 replacing a 4:1 plus a low pass network)
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Zin and Zout of Transistor
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4:1 Transformer with Balun
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4:1 Transformer
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4:1 with embedded lump matching
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At low freq., matched to load line rather than impedance
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4:1 with embedded lump matching
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Picture of TB-160 Link to Application Note TB160Application Note TB160
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TB-160 Topview
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TB-160 Sim. Schematic Link to AWR simulation filesimulation file
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MWO Simulation with layout
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MWO Simulation. Pin =30dbm
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Actual Measurement Pin=30dbm
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MWO Simulation. High Pin
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Actual Measurement Pin=38dbm
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Simulated Pin Pout at 250 Mhz
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Measured Pin Pout at 250 Mhz
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S11
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TB160 ADS Small Signal Simulated
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TB-160 ADS Pwr Simulated
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Simulators This circuit has been successfully simulated using AWR Microwave Office 2002 Ver 5.5 Agilent ADS Results are comparable between simulators
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Conclusion Achieved multi octave broad banding with both Ldmos and Vdmos at high RF Output Levels Good correlation between Actual Measurements to Simulation using Polyfet Spice Models Small physical size matching network made possible by using inherent inductance of coaxial transmission lines along with shunt capacitance. Transistor impedance changes with frequency.
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