Patent attributes
A signal generator of an embodiment has an oscillator to generate an oscillation signal controlled in frequency by an analog control signal; a digital phase detector; a first differentiator; and a comparator outputting digital frequency error information. The generator includes a second differentiator differentiating the frequency setting code to generate a gain value and an inverse number of the gain value; a first multiplier multiplying the digital frequency error information by the gain value, a low-pass filter removing a high frequency component in a multiplication result, and a second multiplier multiplying an output of the low-pass filter by the inverse number. The generator includes a D/A converter converting a multiplication result into analog frequency error information, and an integrator converting the analog frequency error information into analog phase error information to output the analog phase error information as the analog control signal.
