MTT 2002 Seattle June 5th S. K. Leong LDMOS and Vdmos Mhz BroadBand Amps

Mhz Broadband Amps A 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

Polyfet Technical Bulletins

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)

Zin and Zout of Transistor

4:1 Transformer with Balun

4:1 Transformer

4:1 with embedded lump matching

At low freq., matched to load line rather than impedance

4:1 with embedded lump matching

Picture of TB-160 Link to Application Note TB160Application Note TB160

TB-160 Topview

TB-160 Sim. Schematic Link to AWR simulation filesimulation file

MWO Simulation with layout

MWO Simulation. Pin =30dbm

Actual Measurement Pin=30dbm

MWO Simulation. High Pin

Actual Measurement Pin=38dbm

Simulated Pin Pout at 250 Mhz

Measured Pin Pout at 250 Mhz

S11

TB160 ADS Small Signal Simulated

TB-160 ADS Pwr Simulated

Simulators This circuit has been successfully simulated using AWR Microwave Office 2002 Ver 5.5 Agilent ADS Results are comparable between simulators

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.