DEMO MANUAL DC2461A
LTC5548
2GHz to 14GHz Microwave
Mixer with Low IF Frequency
Description
Absolute MAxiMuM input
rAtings
Demonstration circuit 2461A is optimized for evaluation
of the
LTC
®
5548
passive double-balanced mixer with
integrated LO frequency doubler. Its RF port is matched
to 50Ω from 2GHz to 13.6GHz with 9dB return loss, and
the LO port is matched to 50Ω from 1GHz to 12GHz with
10dB return loss. The differential IF port is usable from
DC to 6GHz. The LTC5548 can be used for upconverting
and downconverting applications.
The internal LO doubler can be enabled to allow operation
with a lower frequency LO input signal such as that from
the
LTC6945/LTC6946
or
LTC6947/LTC6948
family of
frequency synthesizers.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2461A
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Supply Voltage (EN) ....................................................4V
Enable Input Voltage (EN) ................–0.3V to V
CC
+ 0.3V
LO Input Power (1GHz to 12GHz) .........................10dBm
LO Input DC Voltage............................................... ±0.1V
RF Input Power (2GHz to 14GHz) .........................20dBm
RF Input DC Voltage ............................................... ±0.1V
IF Input Power (LF to 6GHz) .................................20dBm
IF Input DC Voltage ................................................ ±0.1V
Operating Temperature Range (T
C
) ........ –40°C to 105°C
Junction Temperature (T
J
) .................................... 150°C
Storage Temperature Range .................. –65°C to 150°C
Caution: This part is sensitive to electrostatic discharge
(ESD). Observe proper ESD precautions when handling
the LTC5548.
boArD lAyout
Figure 1. DC2461A
dc2461af
1
DEMO MANUAL DC2461A
proper test setups
Figure 2. Test Setup for Downconverting Mixer 2-Tone Measurements
Figure 3. Test Setup for Upconverting Mixer 2-Tone Measurements
dc2461af
2
DEMO MANUAL DC2461A
notes on test eQuipMent AnD setup
•
High performance signal generators with low harmonic
outputs should be used for 2-tone measurements.
Otherwise, low pass filters at the signal generator
outputs should be used to suppress harmonics.
High quality combiners should be used to present
a broadband 50Ω termination on all ports as well
as provide good port-to-port isolation. Adding at-
tenuator pads further improves source isolation and
helps prevent the signal generators from producing
intermodulation products.
•
Spectrum analyzers can produce significant internal
distortion products if they are overdriven. Generally,
spectrum analyzers are designed to operate at their
best with about –30dBm to –40dBm at their input. The
spectrum analyzer’s input attenuation setting should
be used to avoid saturating the instrument.
Set the spectrum analyzer’s input attenuation depend-
ing on the spectrum analyzer used.
Before performing measurements on the DUT, the
system performance should be evaluated to ensure that
a clean input signal is obtained and that the spectrum
analyzer’s internal distortion is minimized.
•
•
•
Quick stArt proceDure
1. Connect all test equipment as shown in Figure 2.
2. Set the power supply output voltage to 3.3V, and set
the current limit to 200mA.
3. Connect the ground and V
CC
turrets to the power sup-
ply.
BE SURE TO CONNECT THE V
CC
TURRET
BEFORE
THE EN TURRET TO ENSURE THAT THE PART DOES
NOT GET DAMAGED. ALSO, REMOVE POWER FROM
EN TURRET
BEFORE
REMOVING POWER FROM THE
V
CC
TURRET.
4. Connect the EN turret to the power supply.
5. Set the LO signal generator to provide a 5560MHz CW
signal at about 0dBm to the demo board’s LO port.
6. Set the RF signal generators to provide one 5799MHz
CW signal and one 5801MHz CW signal. The signals
should be applied to the 2-way combiner. The output
of the combiner should be applied to the demo board’s
RF input port. The two tones should be set to –5dBm
each at the mixer’s RF input port.
7. Set the spectrum analyzer’s center frequency to 240MHz
with a span of 10MHz.
8. Perform various measurements
(Conversion Gain, OIP3, LO leakage, etc.)
dc2461af
3
DEMO MANUAL DC2461A
pArts list
ITEM
1
2
3
4
5
6
7
QTY
2
2
1
4
3
1
1
REFERENCE
C1, C3
C2, C4
C5
E1 TO E4
J1 TO J3
T1
U1
PART DESCRIPTION
CAP 0.15pF, 100V, ±0.01pF, 0402
,
CAP 22pF, C0G, 50V, 5%, 0402
,
CAP 1µF, X7R, 10V, 10%, 0603
,
TEST POINT, TURRET, 0.061" MTG HOLE
CONN, SMA 50Ω EDGE-LAUNCH
TRANS, MINI-CIRCUITS 4.5MHz TO 3000MHz
IC LTC5548IUDB, QFN 12 PIN, 3mm × 2mm
MANUFACTURER/PART NUMBER
AVX, 04021JR15ZBS
AVX, 04025A220JAT2A
AVX, 0603ZD105KAT2A
MILL-MAX, 2308-2-00-80-00-00-07-0
E F JOHNSON, 142-0701-851
MINI-CIRCUITS TC1-1-13M+
LINEAR TECHNOLOGY CORPORATION, LTC5548IUDB#PBF
Required Circuit Components
dc2461af
4
5
4
3
DEMO MANUAL DC2461A
2
1
scheMAtic DiAgrAM
IF
4
6
T1
J3
3
3
2
2
1
1
GND
IF-
4
IF+
GND
GND
12
RF
2
J1
C1
0.15pF
5
RF
U1
LTC5548
LO
11
2
2
C3
0.15pF
C4
1
22pF
J2
LO
1
GND
VCC
EN
X2
GND
GND
13
VCC
E1
7
8
E3
9
1
6
10
Vcc
E2
2
C2
22pF
C5
1uF
1
1
E4
2
GND
5
4
3
2
1
dc2461af
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
5
