Sine-wave generator circuit

Abstract

A sine-wave generator circuit is provided to generate data representative of a sine wave by using a ROM which stores sine-wave data of only a selected phase region between 0 and .pi./2, for example. The circuit receives input phase data which are represented by twos complements and whose low-order bits are used as address data for the ROM; and each bit of the input phase data has a specific weight factor. When reading out data from the ROM, a normal order or a reverse order for the address data is designated in accordance with high-order bits of the input phase data, so that data representative of other phase regions are generated based on output of the ROM. Then, phase adjustment is performed on the data in accordance with the high-order bits. The data stored in the ROM has certain offset in advance in order to regenerate a sine wave accurately; however, the offset causes an error in output of the ROM. In order to compensate such an error, a correction calculation is performed on the data in accordance with the high-order bits. Moreover, in order to regenerate a cosine wave, sine/cosine-wave designation data are used to cooperate with the high-order bits of the input phase data. Thus, the circuit is capable of generating sine-wave data or cosine-wave data correctly with high precision, regardless of insufficient resolution of address due to the offset.

Dependencies are inferred from the claim text.