SLIM-PDM rev C
Phase Detector Module
10-21-08: Update to
reflect SLIM-PDM Revision B
2-9-09: Update to add Schematic
8-11-09: Update to explain
voltage source option
. Add revision history.
11-20-10: Update to
reflect SLIM-PDM Revision C, addition of 2 capacitors.
11-25-11: Add links to Archived
Phase Detector Module, size-A
Use your mouse's "right click" and "Save Link" to download:
Schematic, in ExpressPCB software.
Parts Layout, in ExpressPCB software. For parts locations.
Parts List in text format. Open with any text reader.
d. PWB-PDM rev A
PWB Artwork, in ExpressPCB software. Use to order from Express.
This SLIM-PDM is constructed on a common printed wiring
board, the PWB-PDM (rev A). Previously,
a separate web page for the PWB. I have deleted that page and
combined the information on this page. If you have constructed
the SLIM-PDM rev A, using the PWB-PDM (rev 0)
board, and would like to improve your PDM accuracy, see the
Modification Procedure on the end of this page.
The SLIM-PDM is a 360 degree, Phase to
Converter. It is specifically designed to operate at 10.7 MHz,
but will operate in the KHz range up to 30 MHz.
The J1 and J2 inputs can be sine or square wave . The min / max
is -20 dBm to +18 dBm. The min / max square input
is 10 mvpp to 5vpp.
Input impedance is nominally 50 ohms, but can be changed to any input
The output, at J3, is a DC voltage that is
the differential phase of the input signals at J1 and J2. The 0v
to +5v output should be loaded with 100 K or higher. A realistic
phase range is from 20 degrees to 340 degrees with error less than .1
Power requirements for the SLIM-PDM is
+7 volts to +15 volts at 50 ma.
Option when using PDM in MSA/VNA
The PDM has a provision to source +5 volts to a
seperate Analog to Digital Converter module, the SLIM-ADC. This
allows both modules to use the same regulated +5volts. This
allows for more accurate Phase measurements. The SLIM-PDM
Rev 0 requires no change or modification for this application.
The SLIM-PDM Rev A requires the additional placement of FBx.
Engineering Change Notice,
The PDM rev B may have a tendency to "self
oscillate". This change is made to prevent this occurance, although
this occurance is quite rare. If your PDM is operating
normally, without any "strange" occurrances, you may omit the
modification. To modify and update SLIM-PDM-revB into SLIM-PDM-revC,
the addition of two capacitors is necessary (C24 and C25). See
Rev C. Also see LAYSLIM-PDM-Rev C.
SLIM-PDM Rev 0, SKPWB-PDM
Rev 0, PWB-PDM Rev 0, PLSLIM-PDM
SLIM-PDM Rev A, SKSLIM-PDM
Rev A, PWB-PDM Rev 0, PLSLIM-PDM
Delete input filter ckt. Change Schematic and Parts List
Schematic Error Note:
2-9-09: In Rev 0 and Rev A versions
PDM Schematic, there is an error in the drawing. U4 has pins 1
and 2 interchanged. The PWB is correct and if it was constructed
per it's Layout, there is no problem. Just annotate the Schematic
to verify that the P1 connector, pin 3 is connected to U4, pin 2.
Annotate that U3 pin 4 is connected to U4 pin 1.
SLIM-PDM Rev B, SKSLIM-PDM
Rev B, PWB-PDM Rev A, PLSLIM-PDM
10-21-08: The SLIM-PDM-revA was redesigned
into revB, to
improve phase performance from about 1 degree resolution, to about .1
degree resolution. The differences between RevB and
RevA is the
addition of a "one-shot", separation of the 5v distribution, and
deletion of input filtering options. The PWB has been revised for
this change. At the bottom of this page is information
how to modify the SLIM-PDM-rev A to improve it's phase
Revised 11-20-10 (current revision)
SLIM-PDM Rev C, SKSLIM-PDM
Rev C, PWB-PDM Rev A, PLSLIM-PDM
10-21-08: The SLIM-PDM-revB was modified
into revC, to
improve the stability of the one-shots (U8 and U9). Two additional
capacitors, C24 and C25 (22 pfd) are added to the schematic and added
to the SLIM assembly. A new PWB is not released. PWB-PDM
Rev A is still current. The layout is modified to LAYSLIM-PDM-revC. The
schematic is modified from SKSLIM-PDM
Rev B to SKSLIM-PDM
Layout and parts
locator for SLIM-PDM
The document "layslim_pdm.pcb" is used to locate
parts on the
board. Do not use to order PWB from Express. Use pwb-pdm.pcb
Note: The layout and schematic show that there are
two ferrite beads supplying
U5, FBx and FB2. The installation of these beads is determined by
how the SLIM-PDM is used in a final configuration of a high level
10-21-08: The Layout (above) and
schematic (below) show the addition of C24 and C25 to reduce the
possibility of PDM instability.
SKSLIM-PDM, Schematic of