DC795A DEMO BOARD QUICK START GUIDE
Description:
The DC795A demo circuit board is intended to demonstrate the capabilities of the LT5527 high-
signal-level downconverting mixer IC for cable and wireless infrastructure applications.
The LT5527 (Figure 1) is a broadband high signal level active mixer optimized for high
downconverter receiver/transmitter applications for cable and wireless infrastructure.
includes a high-speed differential LO buffer amplifier driving a double-balanced mixer.
buffer is internally 50ohm-matched for wideband, single-ended operation with no
components.
linearity
The IC
The LO
external
The LT5527 IC’s RF input port incorporates an integrated transformer and is internally matched to
50ohms over the 1.7GHz to 2.7GHz frequency range. The RF input match can be shifted down to
400MHz, or up to 3.7GHz, with a single shunt capacitor or inductor, respectively. The high level of
integration minimizes the total solution cost, board space and system-level variation.
The LT5527 delivers high performance and small size without excessive power consumption.
The DC795A demo board allows evaluation of the LT5527 downconverting mixer IC for various
receiver and transmitter applications. Its RF input is optimized for 1.7GHz to 2.7GHz frequency
range. The IF output frequency range is centered at 240MHz. The LO is internally matched for
range of frequencies from 1200MHz to 4000MHz.
LO
15
REGULATO
Exposed
Pad
17
Limiting
Amplifiers
GND
12
IF
+
11
3
IF
-
RF
Double-Balanced
Mixer
10
BIAS
BIA
55
GND
9
EN
6
V
CC2
7
V
CC1
Figure 1. LT5527 IC Block Diagram
LT5527 Downconverting Mixer Single-Tone Measurements.
1.
2.
3.
4.
Connect all test equipment as shown in Figure 2.
Set the Power Supply voltage to 5V, and set the current limit to 100mA.
Connect TP1 (EN) to the 5V power supply; the mixer is enabled (on).
Set the Signal Generator #2 to provide a 1900MHz, -10 dBm CW signal to the demo board
RFin port.
5. Set the Signal Generator #1 to provide a -3dBm CW signal, at the desired LO frequency
(HIGH side LO=2140MHz, or LOW side LO=1660MHz) to the demo board LOin port
6. Set the Spectrum Analyzer center frequency to the IF output frequency (240MHz).
(e.g., 500MHz). Perform mixer conversion gain, and 1dB compression measurements.
7. Set the Spectrum Analyzer center frequency to the LO frequency. Perform mixer LO to IF
leakage measurement.
SIGNAL
GENERATOR 1
SIGNAL
GENERATOR 2
SPECTRUM
ANALYZER
POWER SUPPLY
Figure 2. Test Set-Up for Mixer Single-Tone Measurements.
LT5527 Downconverting Mixer Two-Tone Measurements.
1. Connect all test equipment as shown in Figure 3.
1). Use high quality signal generators with low harmonic output for this measurement.
Otherwise, low-pass filters should be used to suppress harmonics.
2). A high quality combiner that provides 50ohm termination on all ports and has good
port-to port isolation should be used.
3). The two 3dB attenuators on the inputs of the combiner are used to further improve
source isolation.
2. Set the Power Supply voltage to 5V, and set the current limit to 100mA.
3. Connect TP1 (EN) to the 5V power supply. Mixer is enabled (on).
4. Set the Signal Generator #1 to provide a -5dBm CW signal, at the desired LO frequency
(HIGH side LO=2140MHz, or LOW side LO=1660MHz) to the demo board LOin port.
5. Set the Signal Generator #2 and #3 to provide two -5dBm CW signals to the demo board
RFin port—one at 1900MHz, and the other at 11901MHz.
6. Set the Spectrum Analyzer center frequency to the IF output frequency at 240MHz. Perform
input 3
rd
order distortion measurement (i.e. IIP3 = P
1
+ (P
1
– P
3
) / 2 – Gc, where P
1
is the
lowest power level of the two desired output tones at either 240MHz or 241MHz, P
3
is the
largest 3
rd
order product at either 239MHz or 242MHz, and Gc is conversion gain. P
1
and
P3 are in units of dBm, and Gc is in dB).
SIGNAL
GENERATOR 1
SIGNAL
GENERATOR 2
3dB PAD
SPECTRUM
ANALYZER
3dB PAD
SIGNAL
GENERATOR 3
POWER SUPPLY
Figure 3. Test Set-Up for Mixer Two-Tone Measurements.
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