ldmos rf amplifier linearization using powersdr mrx …flarc.net/eme-info/pdf/n1jez-1.pdf · ldmos...
TRANSCRIPT
LDMOS RF AMPLIFIER LINEARIZATION USING
POWERSDR MRX PURE SIGNAL Mike Seguin, N1JEZ
MID-ATLANTIC STATES VHF CONFERENCE 2014
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OPENHPSDR HERMES
• DUC/DDC ARCHITECTURE
• CONTINUOUS UNINTERRUPTED RECEIVE COVERAGE FROM 10KHZ TO 55MHZ
• MULTIPLE RECEIVER SUPPORT @ 48/96/192/384 KHZ BW
• FULL DUPLEX OPERATION - ANY SPLIT OVER ENTIRE 160M TO 6M RANGE
• 500MW RF OUTPUT ON 160 – 10M, 350MW ON 6M
• SOFTWARE-SELECTABLE 31dB INPUT ATTENUATOR IN 1dB STEPS
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PURE SIGNAL
• DR. WARREN PRATT, NR0V – PRIMARY ARCHITECT OF PURE SIGNAL • RECIPIENT - ARRL TECHNICAL INNOVATION AWARD 2014
• "PREDISTORTION“ - THE SOFTWARE "PREDISTORTS" THE INPUT SIGNAL
TO THE AMPLIFIER TO CORRECT FOR NON-LINEARITIES IN THE OUTPUT
• “ADAPTIVE PREDISTORTION” - CONTINUOUSLY MONITORS OUTPUT VS INPUT AND MAKES CHANGES BASED ON VARYING CONDITIONS
• FINITE “CORRECTION BANDWIDTH” OF 40 KHZ OR +/- 20 KHZ FROM THE CENTER TRANSMIT FREQUENCY
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Hermes Class A Driver
LDMOS Amplifier
Anritsu MS2721
Dielectric Wattmeter
Bird Sniffer
Bird kW Load
TEST SETUP
50.140 MHz TWO TONES @ 300 WATTS AVG
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FEEDBACK SIGNAL IS SET 1 dB BELOW ADC OVERLOAD
Yaesu FT-817
FUNcube HDSDR
software
Pad
IF TAP
TEST SETUPS - OTA
ANAN-100
FT-817 using 68.33 MHz IF Tap FUNcube Dongle HDSDR Software
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Hermes Based PowerSDR mRX PS
SUMMARY CLASS AB
• PURE SIGNAL LOWERS IMD
• PROVIDE A GOOD CLEAN FEEDBACK SIGNAL FOR PURE SIGNAL
• PAY CLOSE ATTENTION TO THE FEEDBACK SIGNAL LEVEL
• MY SIGNAL IS TOO CLEAN – NOW OTHER OPERATORS ARE GOING TO TUNE RIGHT NEXT TO ME AND SPLATTER ALL OVER ME
• POWERSDR MRX PS HAS A NEW ADDED FEATURE ON THE RIGHT SIDE OF THE SCREEN
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CLASS B LINEARIZATION?
• Is Pure Signal robust enough?
• Normal Class AB bias @ 1.5 A
• ~ 75 watts heat dissipated
• Class B set for 100 ma
• ~ 5 watts heat dissipated
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LDMOS CLASS B WITH PURE SIGNAL ON WHY DOES THE SIGNAL INCREASE?
Channel Pwr -25.20 Pwr Density -59.97 dBm/Hz
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SUMMARY CLASS B
• PURE SIGNAL LOWERS IMD
• IT LINEARIZES THIS LDMOS CLASS B AMP
• MY SIGNAL IS TOO CLEAN – NOW OTHER OPERATORS ARE GOING TO TUNE RIGHT NEXT TO ME AND SPLATTER ALL OVER ME
• JUST TURN OFF PURE SIGNAL
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