Noise shaping circuits and methods with feedback steering overload compensation and systems using the same

A method of noise shaping in a delta-sigma modulator having first and second feedback loops and an output block including a shared quantizer simultaneously responsive to outputs of the first and second feedback loops and steering circuitry comprising:

• steering a first feedback stream from the quantizer to the first feedback loop under normal operating conditions, the first feedback loop having a first filter having a first signal transfer function;
• filtering first feedback signal with the first feedback loop under the normal operating conditions;
• and
• steering a second feedback stream from the quantizer to the first feedback loop and simultaneously a third feedback stream from the quantizer to the second feedback loop under overload conditions to maintain stability of the first feedback loop, wherein the second and third feedback streams substantially sum to a total feedback stream from the quantizer and the second filter has a second signal transfer function differing from the first signal transfer function.

A delta-sigma data converter comprising:

• a delta-sigma modulator comprising:
• a first feedback loop including an input summer and a first filter of an order selected for filtering input first feedback signal under normal operating conditions;
• a second feedback loop including an input summer and a second filter of an order selected for passing energy during overload while remaining stable;
• a quantizer coupled to corresponding outputs of the first and second loops and simultaneously responsive to signals output from the first and second loops;
• and
• steering circuitry having a first output for driving the first loop and a second output for driving the second loop and operable to steer feedback to the summers of the first and second loops, wherein the steering circuitry steers the feedback such that the first loop passes a majority of the energy through the modulator under normal operating conditions and the second loop passes at least some of the energy through the modulator during overload.