| 摘要 |
PROBLEM TO BE SOLVED: To prevent the degradation of receiving sensitivity and enables high speed CD offset correction.SOLUTION: A radio receiving device, which is of direct conversion type, comprises: mixers 4, 5 which frequency convert radio signal received by an antenna 1 into baseband signals by local signals having mutually different phases; differential amplifiers (first amplification circuits) 103, 104 which amplify the baseband signals up to demodulation level; second amplification circuits 54, 55 which are included between the mixers and the first amplification circuits; current variable circuits 68, 69 which add a current 2times a reference current in a multi-stage current mirror configuration; control circuits 66, 67 which correct the DC offsets of the mixers by sending a current from the current variable circuits to the second amplification circuits on the basis of output of the first amplification circuits; and capacitors 74, 75 which are connected between the gates and the sources of P-channel MOSFETs constituting the reference current. |
