Method of forming an audio amplifier voltage reference and structure therefor

A method of forming an audio amplifier voltage reference comprising:

• forming an internal reference voltage having a first internal reference voltage value;
• comparing an output voltage of the audio amplifier voltage reference to the first internal reference voltage value;
• and
• filtering the output voltage using a first cut-off frequency when the output voltage is less than the first internal reference voltage value and using a second cut-off frequency when the output voltage is at least equal to the first internal reference voltage value wherein the second cut-off frequency is less than the first cut-off frequency.

An audio amplifier voltage reference comprising:

• a power input and a power return;
• a comparator having a non-inverting input coupled to a first reference node, an inverting output coupled to an output of the audio amplifier voltage reference, and an output;
• a filter resistor having a first terminal coupled to a second reference node and a second terminal;
• a capacitor having first terminal coupled to the second terminal of the filter resistor and to the output of the audio amplifier voltage reference, and a second terminal coupled to the power return;
• and
• a transistor coupled in parallel across the filter resistor and having a control electrode coupled to the output of the comparator.