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10
Filter Specifications
10.1
Baseband Filter
11
Layers and Schematics
Filter Specifications
9.3.1
Single Ended
To configure the board to monitor the DAC output by utilizing the transformers on board to achieve a
single-ended output, implement the following modifications.
•
Remove R187, R188, R191, R190, R208, R209, R210, R211
•
Place R200, R224, R222, R223: 0-
Ω
resistors
•
Place R179, R183, R212, R213: 100-
Ω
resistor. This configures the DAC output as in the DAC5687
data sheet for 4:1 impedance transformer.
Monitor outputs at J5 and J19.
The TSW3000 Demo Kit layout provides the opportunity to place components to realize up to a 7
th
order
LC filter. The Demo Kit is by default populated with a 500-MHz LC low-pass filter to help eliminate DAC
images and also out of band clock spurs which may mix into RF frequencies.
10.1.1
RF Filter/Output Match
The TSW3000 Demo Kit layout also provides the opportunity to place a small 3
rd
order LC filter on the
output of the modulator for either filtering or impedance matching purposes. This filter has been disabled
by removing the shunt capacitive elements and replacing the series inductor element with a 0-
Ω
resistor.
This chapter contains the layers and schematics for the TSW3000 Demo Kit.
SLWU013A – March 2004 – Revised September 2005
25
