A mixer for downconversion of RF signals includes at least one RF transistor ; at least one switching pair connected to the drain current of the at least one RF transistor ; and a common mode sensing component configured to detect deviations in the common mode output of the switching pair from a specified output; wherein the deviations modify the current of the at least one switching pair. The apparatus further includes a low inertia coupler interconnected between the motor and the shaft. Then, the generated image data of the difference small region is coded and outputted, and then the coded image data of the difference small region is decoded, so that the reconstructed image data of the reproduction small region is generated by adding the decoded image data of the difference small region to the image data of the optimum prediction small region. The protective cover has a transmissive region transmitting the image light reflected by the reflection mirror. The location of glue spots and their size and number are sufficient to maintain the pack together but yet allow the cartons to be separated without destroying the integrity of the panels glued together. The control channel element assignment unit is configured to assign a plurality of continuous CCE to the PDCCH addressed to the mobile station based on an aggregation level changed by the aggregation level determination unit, when failing to assign CCE to the PDCCH addressed to the mobile station.