Oy Nokia Ab

Tapani J Ritoniemi

Aaine H Tenhunen

Teppo J Karema

The invention relates to a method of cascading two or more sigma-delta modulators by applying an error signal representing the quantization error of a preceding modulator to a subsequent modulator in the cascade to be quantized therein, the quantized error signal being thereafter differentiated and subtracted from the quantized output signal of the preceding modulator. To improve the performance of the cascade, in the method according to the invention, the error signal is scaled before said subsequent modulator by a first factor smaller than 1, and the quantized error signal is scaled by a second factor substantially equal to the inverse of the first factor, before being subtracted from the quantized output signal of said preceding modulator.

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Tampere, Finland

Tapani J Ritoniemi