OSCILLATORS WITH ACTIVE HIGHER-IN-ORDER PHASE SHIFT FILTERING

摘要

The present invention proposes a new way of improving the phase stability and frequency selectivity of a phase shift oscillator (100). By introducing a filter-order enhancing feedback loop (124) in association with a phase shift filter (122) in the oscillator, higher-order phase shift filtering can be achieved without using inductive elements as in conventional higher-order LC phase shift filters. This is a great advantage, since a high Q-value can be obtained without limited by the relatively high internal losses of inductive elements (L).