Ripple rejection for amplifier

#(1) Field of the Invention

#The invention relates to a mobile telephone circuit, and more particularly, to a specially filtered power supply voltage for the signal processing module feeding the output stage of a mobile phone to reduce distortions by filtering noise on the regulated voltage line.

#(2) Description of the Prior Art

#In the accompanying drawings forming a material part of this description, there is shown:

#FIG. 1 Prior art illustrates a typical circuit for signal processing modules and related output stages in a bridge configuration.

#FIG. 2 illustrates a schematic illustration of a receive path of a wireless phone.

#The preferred embodiments disclose a novel circuit as part of a mobile phone to reduce distortions caused by the power supply rejection ratio of the power supply voltage and simplifying the layout and the manufacturing process. FIG. 2 shows a schematic illustration of a receive path of a mobile phone. In the shown conception of an embodiment the receive path of a mobile phone comprises the antenna 20, an RF receiver 21, a signal processing module 22, an output stage 23 and a speaker 24. Said novel circuit is comprising the signal processing module 22 and the related power supply.

#FIG. 3 illustrates a preferred embodiment of the invention. The circuit is done in a symmetrical bridge configuration. The positive 1 and negative 2 audio signals and the power supply voltage Vbat 5 comprise the input to the signal processing modules 31 and 32. The output of the signal processing modules are the voltages 35 resp. 35′. Said output voltages of said signal processing modules is fed into the amplifiers 36 resp. 37 of the output stage. Another input of said amplifiers is the reference voltage Vref 9. The power supply for said amplifiers is provided by said voltage Vbat 5. The output of said amplifiers are the voltages Vout 38 resp. Vout 38′ used to drive the loudspeaker 8.

#The power supply required by the signal processing modules is provided by the output voltages Vfilt 34 resp. Vfilt 34′ of the Low Drop Out (LDO) linear voltage regulators 33. The input of said LDOs 33 is the voltage Vbat 5.