The Effect of Noise Transfer Function Shape on Idle Tones in Sigma-Delta Modulators
Work is presented that shows that the behaviour of idle tones in Sigma-Delta modulators depends on whether the noise transfer function has zeros at dc or not. Simulation results for a variety of transfer functions of the same order but a different shape are presented. In particular, no zeros at dc, equiripple zeros, and all zeros at dc. It shows that, without dither, the effects of different filter transfer function shapes on idle tones is minimal for a given order. However, when dither is applied noise transfer functions with all the zeros at dc, Butterworth shapes, are better because lower levels of dither are required to eliminate idle tones.
Click to purchase paper or login as an AES member. If your company or school subscribes to the E-Library then switch to the institutional version. If you are not an AES member and would like to subscribe to the E-Library then Join the AES!
This paper costs $20 for non-members, $5 for AES members and is free for E-Library subscribers.