Verfahren und Vorrichtung zum Unterbinden von Einschaltgeräuschen am Ausgang eines Funktelefonhörers

摘要

A wireless telephone (10) including audio amplifier circuitry (20) that produces reduced "pop" noise in speakers such as in handsfree headsets (HS) is disclosed. The audio amplifier circuitry (20) includes an audio amplifier (22) that drives the headset speaker (HSS). A first transistor (26) has its source-drain path connected between an output (HSO) of the audio amplifier (22) and a power supply voltage (Vdd), and a second transistor (28) has its source-drain path connected between the amplifier output (HSO) and a reference voltage such as ground. The first and second transistors (26, 28) are controlled by control logic (24), in response to the state of various register locations (30) that indicate the powered-up and enabled state of the audio amplifier circuitry (20). Normal and automatic modes for the precharge control are available, with the automatic mode eliminating the need for the precharge enable register location (30d) being written during operation.