Signal generating device

摘要

A signal generating device includes a first digital filter unit outputting a first interpolated signal by interpolating an input signal, a second digital filter unit outputting a second interpolated signal by interpolating the first interpolated signal, a phase calculation unit calculating a phase of a digital signal, a phase-accuracy conversion unit calculating first phase signal and second phase signal, a first memory storing filter coefficients, a first coefficient readout unit reading filter coefficients from the first memory and switching filter coefficients of the first digital filter unit, a phase-error calculation unit calculating a phase error signal, a second memory storing filter coefficients, a second coefficient readout unit reading filter coefficients from the second memory, and a gain normalization unit normalizing a gain of the filter coefficients to maintain a constant sum of the filter coefficients and switching filter coefficients of the second digital filter unit.

主权项

1. A signal generating device comprising:
a first digital filter that outputs a first interpolated signal by interpolating an input signal; a second digital filter that outputs a second interpolated signal by interpolating the first interpolated signal; a phase calculation unit that calculates a phase of a digital signal that changes for each output sampling cycle of the first and second digital filters; a phase-accuracy conversion unit that calculates a first phase signal and a second phase signal on a basis of the phase of the digital signal; a first memory that stores therein a first filter coefficient of the first digital filter; a first coefficient readout unit that reads out the first filter coefficient from the first memory on a basis of the first phase signal and switches the first filter coefficient of the first digital filter; a phase-error calculation unit that calculates a phase error signal on a basis of the second phase signal; a second memory that stores therein a second filter coefficient of the second digital filter; a second coefficient readout unit that reads out the second filter coefficient from the second memory on a basis of the phase error signal; and a gain normalization unit that switches the second filter coefficient of the second digital filter on a basis of the second filter coefficient read out from the second memory in the second coefficient readout unit.