Microwave Amplifier Power Supply

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Microwave Amplifier Power Supply

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

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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-sol
  id-state.html

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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

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Specification of Communication TWT MODEL NO. MEC
5417D From TELEDYNE Electronics
TYPICAL OPERATING CONDITIONS TYPICAL OPERATING CONDITIONS TYPICAL OPERATING CONDITIONS TYPICAL OPERATING CONDITIONS TYPICAL OPERATING CONDITIONS POWER SUPPLY REQUIREMENTS POWER SUPPLY REQUIREMENTS POWER SUPPLY REQUIREMENTS
ELEMENT ELEMENT ELEMENT VOLTAGE CURRENT VOLTAGE MIN VOLTAGE MAX CURRENT MAX
HEATER HEATER HEATER -6 Vdc 1.6 A -5.8 Vdc -6.6 Vdc 2 A
HELIX HELIX W/RF GROUND 7 mA GROUND GROUND 10 mA
HELIX HELIX W/O RF GROUND 1 mA GROUND GROUND 10 mA
GRID ON GRID ON GRID ON 200 Vdc 0.5 mA 100 Vdc 250 Vdc 10 mA
GRID OFF GRID OFF GRID OFF -200 Vdc 0.1 mA -200 Vdc -500 Vdc 1 mA
CATHODE (Ek) CATHODE (Ek) CATHODE (Ek) -10.95 kV 290 mA -10 kV -11 kV 325 mA
COLLECTOR W/ RF 1 1 6.1 kV 75 mA 56 x Ek 2 56 x Ek 2 125 mA
COLLECTOR W/ RF 2 2 4.4 kV 208 mA 40 x Ek 2 40 x Ek 2 125 mA
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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
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Who are in Business? (Power Supply Manufactures)
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Left 600W Tri-band CW TWTARight Power Supply
Products of ETM Electromatic Inc.www.etm-inc.com
Interchangeable module-type Power Supply
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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
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High Voltage Filters Ready to be Tested
Right High-Voltage Filters after assembly ready
to be testedLeft Potted filters to be
retested (Potting materials High-Voltage
Insulation)
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Testing High-Voltage
High-Voltage modules are tested in flouriner
(liquid insulator) before potted with liquid
silicone rubber
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Our Customers
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Block Diagram of Switching PS
-
HV Filter
-
-
-
DIODE
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My Current Machine 10kV 4-Collectors Test Set
for L3
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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
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Presentation Notes

• Input Filter
• 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

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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

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