DEMO MANUAL DC1705C
LTC6946
Ultralow Noise and Spurious Integer-N
Frequency Synthesizer with Integrated VCO
DESCRIPTION
DC1705C features the
LTC
®
6946,
an ultralow noise and
spurious integer-N frequency synthesizer with integrated
VCO. The VCO uses no external components and is inter-
nally calibrated without external system support.
There are four options of the DC1705C, one for each ver-
sion of the LTC6946. Table 1 summarizes the available
DC1705C options.
Each DC1705C provides 50Ω SMA connectors for the
reference frequency input, f
REF
(REF+ IN), the reference
output buffer (REF OUT), and the differential RF output
(RF
+
and RF
–
). A DC590 USB serial controller board is
used for SPI communication with the LTC6946, controlled
by the supplied PLLWizard™ software.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1705C
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
PLLWizard and QuikEval are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
Figure 1. Proper Measurement Equipment Setup
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DEMO MANUAL DC1705C
TYPICAL DC1705C REQUIREMENTS AND CHARACTERISTICS
PARAMETER
3.3V Power Supply
5V Power Supply
REF
+
IN, Reference Frequency
REF OUT, Buffered Reference
RF
+
and RF
–
INPUT OR OUTPUT
Input
Input
Input
Output
Two Outputs
PHYSICAL LOCATION
3.3V and GND Banana Jacks
5V and GND Banana Jacks
J1 SMA Connector
J3 SMA Connector
J4 and J5 SMA Connectors
DETAILS
Low Noise and Spur-Free 3.3V, 115mA
Low Noise and Spur-Free 5V, 45mA
Low Noise 10MHz or 100MHz*, 6dBm into 50Ω
(Note 1)
Frequency = f
REF
, 0dBm
Frequency: 900MHz*, Power: 0dBm, Frequency
Range: Depends on the version of the LTC6946
device – refer to Table 1, Step Size: 200kHz*
Loop Bandwidth
–
Set by Loop Filter Component Values 47kHz*
* These frequencies are for the DC1705C pllset files included with PLLWizard.
Note 1:
A low noise 10MHz or 100MHz reference frequency, such as the Wenzel 501-04608A or 501-04516D OCXO, is recommended. If using a different
frequency, make sure to update the f
REF
and R_DIV boxes under the System tab in PLLWizard so that f
PFD
is still 1MHz. For example, if a 20MHz clock is
used, f
REF
should be changed to 20MHz and R_DIV to 20. REF BST and FILT under the System tab in PLLWizard might need to be changed if the reference
frequency and/or power is different than what is recommended in the table above. More information can be found in the LTC6946 data sheet.
Table 1. DC1705C Options and Frequency Ranges
ASSEMBLY VERSION
DC1705C-A
DC1705C-B
DC1705C-C
DC1705C-D
PART NUMBER
LTC6946IUFD-1
LTC6946IUFD-2
LTC6946IUFD-3
LTC6946IUFD-4
VCO FREQUENCY RANGE (GHz)
2.240 to 3.740
3.080 to 4.910
3.840 to 5.790
4.200 to 6.390
OUTPUT DIVIDER SETTINGS
Integers 1 through 6
Integers 1 through 6
Integers 1 through 6
Integers 1 through 6
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DEMO MANUAL DC1705C
QUICK START PROCEDURE
The DC590 and PLLWizard application are required to
control the DC1705C through a personal computer (PC).
DC590 Configuration
The DC590’s QuikEval™ drivers must be installed before
the DC590 will be able to communicate with the LTC6946.
To configure the DC590, follow the procedure below, start-
ing with step 1. If you have already installed the DC590
software previously, skip to step 5.
Note:
Once the QuikEval software is installed, the applica-
tion does not need to be executed to run PLLWizard or to
control the DC1705C.
1. Do Not plug in the DC590 before running the installation
program.
2. Download the QuikEval installation program from
http://www.linear.com/software.
3. Run the QuikEval installation program and follow the
on-screen instructions. More detailed installation infor-
mation may be found in the DC590’s Quick Start guide.
4. Exit the QuikEval program once the installation is com-
plete, as it is not needed to run the PLLWizard software.
5. Place the DC590 jumpers in the following positions:
JP4
EE Must be in the “EN” position.
JP5
ISO “ON” must be selected.
JP5
SW “ON” must be selected.
JP6
VCCIO “3.3V” must be selected. This sets the SPI
port to 3.3V operation.
6. Connect the DC590 to one of your computer’s USB
ports with the included USB cable.
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DEMO MANUAL DC1705C
QUICK START PROCEDURE
Figure 2. DC590 Jumper Locations
PLLWizard Installation
The PLLWizard software is used to communicate with
the LTC6946 synthesizer. It uses the DC590 to translate
between USB and SPI-compatible serial communications
formats. It also includes advanced PLL design and simula-
tion capabilities. The following are the PLLWizard system
requirements:
,
• Windows Operating System: Windows XP
Windows 2003 Server, Windows Vista, Windows 7
• Microsoft .NET 2.0 or later
• Windows Installer 3.1 or later
• Linear Technology’s QuikEval and DC590 hardware
Microsoft .NET
You must have Microsoft .NET 2.0 or later installed on
your computer. PLLWizard will not run without it. Note that
with Windows Vista and Windows 7, you should have at
least version 3.5 pre-installed.
To manually determine your version of .NET using Win-
dows XP click
Start Menu
→
Settings
→
Control Panel
,
→
Add or Remove Programs.
Depending upon your .NET version, choose one of
two PLLWizard setup programs, downloaded from
http://www.linear.com/software.
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DEMO MANUAL DC1705C
QUICK START PROCEDURE
Either setup program will automatically install Microsoft
.NET if a compatible .NET version is not found. But, the
installation source depends upon which file you down-
loaded from Linear Technology’s website. You should pick
one of the following two choices, depending upon your
version of .NET.
Table 2. PLLWizard Installation File
FILE
PLLWizardSetup.exe
PLLWizardSetup_net20.exe
.NET 2.0 SOURCE
Latest Version Downloaded from Microsoft
2.0 SP2 Included (Much Larger File Size)
• Choose
PLLWizardSetup
if you have .NET 2.0 or later,
have Windows Vista or Windows 7, or if you have less
than .NET 2.0 but want the latest .NET installed.
• Choose
PLLWizardSetup_net20
if you have less than
.NET 2.0, and want faster installation (no additional
Microsoft downloads are needed, but the file size is
much larger).
The setup file will verify and/or install Microsoft .NET and
install PLLWizard. Refer to the Help menu for software
operation.
Figure 3. PLLWizard Screenshot
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