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Figure 1: Up-conversion test setup
with no filters, reflective filters
(lumped element and LTCC), and
reflectionless filters at the IF input
and RF output ports. Low and
high third order intermodulation
frequencies were measured at the RF
output for all cases and compared.
Summary results are presented in
Table 2. For brevity sake, results
are shown here only for RF output
of 800 MHz. Results for RF output
of 2200 MHz are comparable and
are available by request from Mini-
Circuits.
Notice that in all cases where
reflective filters were used, the filters
contribute to a significant increase in
thirdorder intermodulation product
(IM 3) relative to the IM3 of the
mixer when no filters are used.
When reflectionless filters are used,
however, measured IM 3 is nearly
equal to or less than that of the
mixer alone. These results therefore
demonstrate that using reflectionless
filters in the up-conversion circuit
achieves an improvement in third
order intermodulation performance
ranging from about 5 dB to 18
dB relative to performance when
conventional filters are used in the
same circuit.
Down-Conversion Test
Setup
Two-tone intermodulation tests
were performed in downconverter
configuration as shown in Figure
2. As in the up-conversion setup,
different mixer-filter combinations
were tested to compare reflectionless
filters with various conventional
filters. Mixers were also tested with
no filters for reference. Third order
intermodulation measurements were
made for RF inputs of 800MHz and
2200 MHz with two-tone spacing
Table 1: Summary of Test Conditions for Two-Tone Intermodulation Test
in Up-converter Configuration
FILTER PO-
SITIONS
• Case 1: NO FILTERS
• Case 2: REFLECTIVE FILTERS (VARIOUS) on RF and
IF PORTS
• Case 3: REFLECTIONLESS FILTERS on RF and IF
PORTS
IF INPUT
150 MHz
TONES TWO TONES SPACING: 1 MHz (149 MHz AND 150
MHz)
MIXERS
TESTED
•ADE-10H+
•SYM-30DHW+
FILTERS
TESTED
LUMPED ELEMENT (Sharp Filters)
RF
SLP-1000
IF
SLP-150+
SLP-1200+
SLP-2400+
SLP-2950+
LTCC FILTERS (Shallow Slope)
RF
VLF-800+
IF
VLF-160+
VLF-1000+
VLF-2250+
VLF-2500+
REFLECTIONLESS FILTERS
RF
XLF-861+
IF
XLF-151+
XLF-122+
XLF-252+
Test & Measurement
Special Edition
New-Tech Magazine Europe l 53