Linear Technology DC503A, Quick Start Manual

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LT5512 Downconverting Mixer Two-Tone Measurements for 1230MHz CATV Band.
1. Connect all test equipment as shown in Figure 3.
Note: 1). A high quality combiner that provides 50-ohm termination on all ports and has
good port-to-port isolation should be used.
2). The two 3dB attenuators on the inputs of the combiner are used to further
improve source isolation.
2. Set the Power Supply output voltage to 5V, and set the current limit to 100mA.
3. Connect TP1 (EN) to the 5V power supply. Mixer is in ENABLE mode.
4. Set the Signal Generator #1 to provide a 1800MHz, -10dBm, CW signal to the demo board
LOin port.
5. Set the Signal Generator #2 and #3 to provide two -10dBm CW signals to the demo board
RFin port—one at 1229.9MHz, and the other at 1230.1MHz.
6. Set the Spectrum Analyzer’s center frequency to 570MHz. Perform input 3
rd
order
distortion measurement. (IIP3 = P1 + (P1 – P3) / 2 – Gc, where P1 is the lowest power level
of the two desired output tones at either 569.9MHz or 570.1MHz, P3 is the largest 3
rd
order
product at either 569.7MHz or 570.3MHz, and Gc is conversion gain. P1 and P3 are in units
of dBm, and Gc is in dB.)
SPECTRUM
ANALYZER
SIGNAL
GENERATOR 1
SIGNAL
GENERATOR 2
POWER SUPPLY
Figure 3. Test Set-Up for Mixer Two-Tone Measurements.
SIGNAL
GENERATOR 3
∑
3dB PAD
3dB PAD