Microwave Amplifier Power Supply High Voltage Switching Power Supply Design at System Level Sharing Industry Experience with EE136 Alex Chen MONDAY December 1, 2003

BASICS of Traveling Wave Tube (TWT) Amplifier Reference: http://www.twtas.com/pictures/factorywalk/faccathode.html BASICS of Traveling Wave Tube (TWT) Amplifier

Key Notes of TWTA: Heater/Filament is closest to Cathode Voltage. Heater and Cathode act as electron gun, and they are on the side RF Input. Collectors sits on RF output. Electrons are fired from Cathode and received from Collectors. RF signal is amplified through bunching effect after traveling along the path of Helix coil.* Higher Cathode voltage  Higher RF Power * Advantage of TWTA (over solid state amplification) is the linearity and output power* TWTA Efficiency: 50% to 60% vs. Solid State: 25% to 30% Ranges of Frequency for TWTA: 1Ghz – 40 Ghz *Additional Information: http://www.djmelectronics.com/articles/twt-vs-solid-state.html

Application of TWTA Point to Point Communication Satellite communication and Rader Appz Missile tracking application for military Television live broadcasting LIVE news vans with satellite dishes on the roof carry TWTA inside

TYPICAL OPERATING CONDITIONS POWER SUPPLY REQUIREMENTS Specification of Communication TWT: MODEL NO. MEC 5417D From TELEDYNE Electronics TYPICAL OPERATING CONDITIONS POWER SUPPLY REQUIREMENTS ELEMENT VOLTAGE CURRENT VOLTAGE MIN VOLTAGE MAX CURRENT MAX HEATER -6 Vdc 1.6 A -5.8 Vdc -6.6 Vdc 2 A HELIX W/RF GROUND 7 mA 10 mA W/O RF 1 mA GRID ON 200 Vdc 0.5 mA 100 Vdc 250 Vdc GRID OFF -200 Vdc 0.1 mA -500 Vdc CATHODE (Ek) -10.95 kV 290 mA -10 kV -11 kV 325 mA COLLECTOR W/ RF #1 6.1 kV 75 mA 56% x Ek + 2% 125 mA #2 4.4 kV 208 mA 40% x Ek + 2%

Key Notes for Reading the Specification of TWTA: Cathode (Ek) Voltage is NEGATIVE. Collector 1/2 reference to Cathode Voltage Collector Voltages read POSITIVE Heater Voltage also references Ek Test Equipments (Ex: 1kX Divider) are reference to Ground GROUND Collector 1 Collector 2 Cathode Heater Comparing Relative Voltages -10kV +6kV +4kV -6V

Who are in Business? (Power Supply Manufactures)

Left: 600W Tri-band CW TWTA Right: Power Supply Products of ETM Electromatic Inc. www.etm-inc.com Interchangeable module-type Power Supply Left: 600W Tri-band CW TWTA Right: Power Supply

More Products Astrium Project for Skynet: -15kV Cathode Voltage Power Supply (Far Left) -RF Amplifier by CPI (Right) with input RF source (front) Output dummy load (back) 4-Astrium Units Combined for Project Skynet

High Voltage Filters Ready to be Tested Right: High-Voltage Filters after assembly ready to be tested Left: Potted filters to be retested (*Potting materials = High-Voltage Insulation)

Testing High-Voltage High-Voltage modules are tested in flouriner (liquid insulator) before potted with liquid silicone rubber

Our Customers

Block Diagram of Switching PS ~ + ~ - HV Filter ~ - ~ + ~ - ~ + ~ - ~ + DIODE Block Diagram of Switching PS

My Current Machine: 10kV 4-Collectors Test Set for L3

Major Components Input Filter or PFC H-Bridge: Buck + Full-Bridge Pulse Width Modulation for H-Bridge Diode High-Voltage Filter Heater Grid Modulator AC Fan Driver for cooling Logic & Control Human Interface Control Low Voltage Power Supply RED: Topics will not be discussed in class

Presentation Notes: Input Filter H-Bridge PWM Board Diode LRC filtering with delay and soft-start Phase Loss detection circuit H-Bridge Isolated Buck Converter to Full-Bridge PWM controls Buck Converter. Duty of Full-Bridge is fixed at 50%. The use of transformers for gate driver circuits PWM Board Controls both buck drive and full-bridge. Master/Slave Configuration for Buck to Full-Bridge Gate Driver Chips Pre/Post Regulation Diode Primary and Secondary Transformers Voltage Doublers Circuit High-Voltage diodes are used for rectification High-Voltage Filter RC Low Pass Filter Feedback sense from Cathode Voltage to PWM Post Regulation Arc Detection

Fast Heater 400Hz Sinus Fan Driver Forward Regulator Presentation Notes (continue): Fast Heater Forward Regulator Same chip as PWM chip Two different voltage reference Single-shot re-triggerable chip Voltage Sense / Current Sense 400Hz Sinus Fan Driver Boost, Half Bridge, Flyback Hi/Low sides driver Microcontroller with oscillator Over voltage / Over Current Detection