Abstract
Single-amplifier filter biquads and especially Sallen-Key filters are widely used to build higher-order filter cascades. This paper investigates high-frequency current amplifier non-idealities and their effects on all-pole Sallen-Key filter biquads. It is shown that a non-ideal current amplifier input causes parasitic zeros in the filter transfer function, and thus imposes fundamental limitations on the realizable pole frequency. Design equations are given, providing compensation for the amplifier's port impedances and its phase lag, by predistortion of the component values. It is also shown how design specifications for a current-amplifier can be derived from the filter specification, minimizing the amplifier's power dissipation. Finally, a video-frequency lowpass filter is discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 57-60 |
| Number of pages | 4 |
| Journal | Proceedings - IEEE International Symposium on Circuits and Systems |
| Volume | 1 |
| State | Published - 1998 |
| Externally published | Yes |
| Event | Proceedings of the 1998 IEEE International Symposium on Circuits and Systems, ISCAS. Part 5 (of 6) - Monterey, CA, USA Duration: 31 May 1998 → 3 Jun 1998 |