DC503A Analog Devices

DC503A DEMO BOARD QUICK START GUIDE Description: The DC503A demo circuit board is intended to demonstrate the capabilities of the LT5512 downconverting mixer IC for cable infrastructure applications. The LT 5512 (Figure 1) is a broadband high signal level mixer IC optimized for high linearity downconverter applications including cable and wireless infrastructure. The IC includes a differential LO buffer driving a double-balanced mixer. An integrated RF amplifier improves LO- RF isolation and eliminates the need for precision external bias resistors. The LT5512 is a high-linearity alternative to passive diode mixers. Unlike passive mixers, which have conversion loss and require high LO drive level, the LT5512 delivers conversion gain and requires significantly lower LO drive levels. The DC503A demo board downconverts 1230MHz RF input to 270-870MHz IF output. The LO is injected from the high-side between 1500MHz and 2100MHz. Figure 1. LT5512 IC Block Diagram 1 of 11 LT5512 Downconverting Mixer Single-Tone Measurements for 1230 MHz CATV Band. 1. Connect all test equipment as shown in Figure 2. 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 an 1800MHz, -10dBm, CW signal to the demo board LOin port. 5. Set the Signal Generator 2 to provide a 1230MHz, -10dBm, CW signal to the demo board RFin port. 6. Set the Spectrum Analyzers center frequency to 570MHz. Perform mixer conversion gain, and 1dB compression measurements. 7. Set the Spectrum Analyzers center frequency to 1800MHz. 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. 2 of 11