LOCAL OSCILLATOR LEAKAGE REMOVING CIRCUIT AND FEED BACK COMPENSATION LOOP

摘要

PURPOSE: A method is provided to reduce the level of the undesired signal which is generated in a frequency converter device by realizing a local oscillator leakage reducing circuit. CONSTITUTION: The frequency converter device(20) receives an IF input data signal and at the same time the local oscillator signal from the local oscillator(10) is input to the frequency converter device. The complex signal from the frequency converter device is input to a detecting circuit(30) and accordingly the detecting circuit generates an error voltage in proportion to the level of the undesired signal. Based on this invention, the quality of the signal can be improved by the removal of the undesired signal on transmission. That is, the local oscillator leakage signal is removed by using the detecting circuit and a nulling circuit according to the result that the frequency converter device has a single input port or a multi input port.