The HMC553 is a passive double balanced mixer that can be used as an upconverter or downconverter between 7 and 14 GHz. The miniature monolithic mixer is fabricated in a GaAs MESFET process, and requires no external components or matching circuitry. The HMC553 operates with LO drive levels as low as +9 dBm and provides excellent LO to RF and LO to IF isolation due to optimized balun structures. Measurements were made with the chip mounted into in a 50 ohm test fixture and includes the parasitic effects of wire bond assembly. Connections were made with a 1 mil wire bond with minimal length (<12 mil).