| 摘要 |
PURPOSE:To provide the carrier leak adjusting circuit which performs adjustment without inputting actual data to an quadrature modulator by inputting digital data, whose value is closest to the center value of input data, to a D/A converter. CONSTITUTION:ROMs 1 and 2 of FFs are provided in preceding stages of D/A converters 11 and 21, and input digital data D1 and D2 are outputted to converters 11 and 21 as they are by an external switching signal C at the time of normalcy. At the time of maintenance, output data to converters 11 and 21 are as follows independently of input data D1 and D2; 8-bit data of the center value in a prescribed range of converters 11 and 21 is always outputted or 8-bit data '10000000' of value 128 or '011111111' of value 127 closest to center value 127.5 is always outputted if the input range is 0 to 255 of 8 bits. As the result, the simple carrier leak adjusting circuit is constituted which performs adjustment without inputting actual data to the quadrature modulator. |
