| 摘要 |
A data converting unit (100) converts an input signal into digital data having a predetermined number of bits at clocks generated in a predetermined cycle ts, and performs squared detection of the digital data to output the resultant data as phase-detected data. A log converting unit (200) performs logarithmic conversion of the phase-detected data output from the data converting unit (100). The log converting unit (200) has an exponent-mantissa separator (210) which receives the phase-detected data output from the data converting unit (100), a mantissa calculating table (220) which is accessed by the mantissa data output from the exponent-mantissa separator (210), an exponent output unit (230) which outputs a logarithm corresponding to the exponent data based on the exponent data output from the exponent-mantissa separator (210), and an adder (240) which adds the logarithm corresponding to the mantissa data output from the mantissa calculating table (220) to the logarithm corresponding to the exponent data output from the exponent output unit (230), and outputs a logarithm depending on the phase-detected data. |
