Mirror of www.qsl.net/ke5fx/synth.html


A Versatile Hybrid Synthesizer for UHF and Microwave Projects


Block diagram AD9854ASQ / ADF4112 synthesizer module

Four ICs pack tremendous power and flexibility into a 4" Hammond 1590-series chassis. Controlled by the PC parallel port, this hybrid DDS/PLL synthesizer delivers full-octave coverage between 1000 and 2000 MHz with sub-1 Hz resolution and commercial-quality phase-noise performance.


Close-in phase noise plot, Tektronix 494AP with GPIB plotter emulation

Icom IC-R7000 first LO synthesizer: -51.5 dBc/Hz at 250 Hz
KE5FX hybrid synthesizer: -80.3 dBc/Hz at 250 Hz


Phase noise plot, Tektronix 494AP with GPIB plotter emulation

Icom IC-R7000 first LO synthesizer: -70.5 dBc/Hz at 1 kHz
KE5FX hybrid synthesizer: -83.7 dBc/Hz at 1 kHz


Wideband phase noise plot, Tektronix 494AP with GPIB plotter emulation

Icom IC-R7000 first LO synthesizer: -99.9 dBc/Hz at 10 kHz
KE5FX hybrid synthesizer: -91.9 dBc/Hz at 10 kHz


Narrowband loop-bandwidth comparison, Tektronix 494AP with GPIB plotter emulation

1500 Hz loop bandwidth: -81.5 dBc/Hz at 250 Hz
2500 Hz loop bandwidth: -80.3 dBc/Hz at 250 Hz
3500 Hz loop bandwidth: -82.3 dBc/Hz at 250 Hz


Loop-bandwidth comparison, Tektronix 494AP with GPIB plotter emulation

1500 Hz loop bandwidth: -79.3 dBc/Hz at 1 kHz
2500 Hz loop bandwidth: -83.7 dBc/Hz at 1 kHz
3500 Hz loop bandwidth: -84.9 dBc/Hz at 1 kHz


Wideband loop-bandwidth comparison, Tektronix 494AP with GPIB plotter emulation

1500 Hz loop bandwidth: -93.9 dBc/Hz at 10 kHz
2500 Hz loop bandwidth: -91.9 dBc/Hz at 10 kHz
3500 Hz loop bandwidth: -87.9 dBc/Hz at 10 kHz


VCO crossband tuning step function, Tektronix 2430A with GPIB plotter emulation

Icom IC-R7000 first LO synthesizer VCO tuning line, 770 MHz to 1030 MHz
Icom IC-R7000 first LO synthesizer VCO tuning line, 1030 MHz to 770 MHz
KE5FX hybrid synthesizer VCO tuning line, 1000 MHz to 2000 MHz
KE5FX hybrid synthesizer VCO tuning line, 2000 MHz to 1000 MHz


Digi-Key X704-ND 15 kHz 4-pole crystal filter response compared to DDS range

Improved spur performance (see spur-search results below) is obtained with an inexpensive monolithic crystal filter following the AD9854 DDS. This graph shows the DDS coverage range overlapped with the crystal filter's close-in response in an early prototype.


ddspll3.gif


ddspll4.gif


ddspll2.gif


ddspll1.gif


ddspll5.gif

PC parallel port and Atmel AVR connections to J501

IDC Connector LPT Port AVR Port 'A' Signal
1 15 PA0
2 9 PA1
3 - -
4 6 PA2
5 7 PA3
6 8 PA4
7 4 PA5
8 2 PA6
9 3 PA7
10 18-25 GND


Complete parts list including Digi-Key, Mini-Circuits, and Analog Devices part numbers
Note: Component values in list supercede those in schematics above

R101: 1.3K ohms (P1.3KECT-ND)
R102, 103: 100 ohms (P100ECT-ND) (50-ohm external clock input only)
R102, 103: 1K ohms (P1.0KECT-ND) (Internal clock source only)
R403: 1K ohms (P1.0KECT-ND)
R104: 3.9K ohms (P3.9KECT-ND)
R105-108, 212: 51 ohms (P51ECT-ND)
R201-203: 18 ohms (P18ECT-ND)
R206, 207, 510-514: 10K ohms (P10KECT-ND)
R210, 211, 218: 22 ohms (P22ECT-ND)
R213-216: 470 ohms (P470ECT-ND)
R217: 4.7K ohms (P4.7KECT-ND) (ADF4112 PLL chip only; omit for LMX2326)
R301, 303: 4.7K ohms (P4.7KECT-ND)
R401, 402, 501, 507-509, 109-112: 100 ohms (P100ECT-ND)
R502-506: 3.3K ohms (P3.3KECT-ND)

C101, 103, 207, 208, 209, 401: 0.01 uF/50V ceramic (399-1234-1-ND)
C102, 104, 106, 202, 204, 205, 211, 215, 219, 224, 226, 309, 311, 312, 315, 317, 318, 407, 408: 0.1 uF/50V ceramic (PCC104BCT-ND)
C201, 203, 206, 210, 217, 220: 100 pF/50V ceramic (399-1205-1-ND)
C214, 321: 47 uF/35V electrolytic (PCE3280CT-ND)
C218, 228, 302, 304, 307, 308, 313, 314, 409: 10 uF/16V tantalum (399-1595-1-ND)
C221-223, 225, 406: 0.001 uF/50V ceramic (PCC102BCT-ND)
C301, 319, 320, 322: 10 uF/35V electrolytic (PCE3413CT-ND)
C403, 405: 270 pF/50V NPO ceramic (399-1209-1-ND)
C404: 470 pF/50V NPO ceramic (399-1213-1-ND)

D301-303: 1N4002 (DL4002DICT-ND)
D304: 5.6V 500 mW Zener (BZT52C5V6-7DICT-ND)
D306: 5.6V 500 mW Zener (5V VCOs only) (BZT52C5V6-7DICT-ND)
D306: 12V 500 mW Zener (12V VCOs only) (BZT52C12-7DICT-ND)

F401: ECS-10.7-15B monolithic crystal filter, +/- 7.5 kHz bandwidth, 25 kHz stopband (X704-ND)

J101, 201: SMA female bulkhead jack (J569-ND)
J301: 4-position straight header (A1912-ND)
J501: 10-position shrouded header (MHB10K-ND)

L402,403: 0.91 uH RF choke (DN1015CT-ND)
L201, 202, 204-207, 301, 404: 33 uH 115 mA RF choke (TKS2638CT-ND)
L203: Mini-Circuits ADCH-80A

Q301, 303: 2SC1847 (2SC18470Q-ND)

T401, 402: Mini-Circuits T36-1-KK81 36:1 RF transformer

U101: Analog Devices AD9852AST DDS synthesizer
U102: Clock module for internal-clock option (ECS-3953M)
U201: Analog Devices ADF4112BRU 3.0 GHz RF PLL frequency synthesizer
U201: National Semiconductor LMX2326TM 2.8 GHz RF PLL frequency synthesizer (LMX2326TM-ND)
U202: Burr-Brown OPA27 low-noise operational amplifier (OPA27GU-ND)
U203: Mini-Circuits ROS-2150VW 1-2 GHz VCO
U204: Mini-Circuits GALI-5 monolithic amplifier
U301, 302: Linear Technology LT1086-3.3 voltage regulator (LT1086CT-3.3-ND)
U304: 7812 voltage regulator (NJM7812FA-ND)
U401: Linear Technology LT1016 precision comparator (LT1016CS8-ND)

Miscellaneous hardware and optional parts

Hammond 1590BB aluminum enclosure (HM152-ND)
TO-220 mounting kits for U301, U302 (4724K-ND)
10-position IDC socket for J501 (MKC10A-ND)
10-position ribbon cable (MC10G-5-ND

Loop filter components (ROS-2150VW VCO, 2.5 kHz loop bandwidth):

R208: 150 ohms (P150ECT-ND)
R209: 82 ohms (P82ECT-ND)
C212: 1 uF/35V tantalum (PCS6105CT-ND)
C213: 0.1 uF/50V ceramic (PCC104BCT-ND)
C216: 0.1 uF/50V ceramic (PCC104BCT-ND)


Thanks to Richard Hosking, VK6BRO for his schematic-drafting work and design suggestions! PC boards are available for US $25.00 postpaid (including international orders). Email jmiles@pop.net for details.

AutoTrax .PCB file (by Richard Hosking) -- tested and working with components above

Microsoft Works spreadsheet for loop-filter design (by Richard Hosking)

Miscellaneous Atmel assembly routines for AD9852 and related components (by Richard Hosking)

Random spur search results for 180 kHz ceramic filter following DDS, 100 MHz clock, 1500+ samples (6.2MB)

Random spur search results for 25 kHz crystal filter following DDS, 100 MHz clock, 1600+ samples (6.7MB)

Random spur search results for 25 kHz crystal filter following DDS, 16.384 MHz clock x 7, 1600+ samples (6.7MB)

Random spur search results for 25 kHz crystal filter following DDS, 10 MHz clock with adaptive multiplier (8-12X) algorithm, 5000 samples (20MB)
No significant spurs at any of 5,000 randomly-selected frequencies

Unzip each of the above files into separate, empty directories and run HPGLVIEW.EXE to browse spectrum-analyzer plots -- or download the current version of the HP-GL/2 tools (highly recommended!)


Cross-platform Atmel/Win32 C++ control software, with source (New as of 19-Oct-02!)



Technical Correspondence


1 Hz resolution bandwidth, 50 Hz/division, HP 8563E 3 Hz resolution bandwidth, 100 Hz/division, HP 8563E

Photo courtesy Miguel Llanes, KG4LXC SSB sweep of 0-15 Hz from carrier, HP 8563E



November 3, 2003 - Miguel Llanes of Rockwell-Collins sends along a few shots of his synthesizer PCB and its performance as characterized on an HP 8563E spectrum analyzer. This FFT-based instrument delivers better close-in measurement performance than the Tektronix 494AP used to capture the screenshots at the top of the page.

Miguel was also kind enough to point out some notation errors on the schematics. As the parts list indicates, C214 and C321 should both be 47 uF/35V parts, while C313 should be 10 uF/16V. In the previous schematic drafts, all three capacitors were marked as 22 uF. (It's important not to use too large a capacitor at C313, as I've seen U201 malfunction with slow power-supply risetimes at the junction of pins 10 and 15. -- jm)

One correction to the parts list was also necessary: the Digi-Key part number for C101, 103, 207, 208, 209, and 401 has changed from PCC103BCT-ND to 399-1234-1-ND. The former part number no longer appears to be stocked.

All of these corrections have been made to the page contents above. Many thanks to Miguel, KG4LXC for the feedback!



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