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 LORF 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.