Circuit for Use with a Loudspeaker for Portable Equipments

The invention relates to a circuit (100) for use with a loudspeaker (104) having a first differential input terminal (t1) and a second differential input terminal (t2), the circuit (100) comprising: a differential power amplifier (103) having a first differential output terminal (t3) operatively connected to the first differential input terminal (t1) of the loudspeaker (104) and a second differential output terminal (t4) operatively connected to the second differential input terminal (t2) of the loudspeaker (104);-a first resistor (RS1) disposed between the first differential output terminal (t3) of the differential power amplifier (103) and the first differential input terminal (t1) of the loudspeaker (104); a second resistor (RS2) disposed between the second differential output terminal (t4) of the differential power amplifier (103) and the second differential input terminal (t2) of the loudspeaker (104). The circuit (100) further comprises: a first resistive module (RR1, RR2) arranged to generate on a respective output terminal (t5) a first control voltage (VIN), the first resistive module (RR1, RR2) having a first input terminal (t6) connected to the first differential output terminal (t3) of the power amplifier (103) and a second input terminal (t7) connected to the second differential input terminal (t2) of the loudspeaker (104), a second resistive module (RR3, RR4) arranged to generate on a respective output terminal (t8) a second control voltage (VIP), the second resistive module (RR3, RR4) having a first input terminal (t9) connected to the second differential output terminal (t4) of the power amplifier (103) and a second input terminal (t10) connected to the first differential input terminal (t1) of the loudspeaker (104). The loudspeaker circuit (100) being arranged to control the differential power amplifier (103) on the basis of the first control voltage (VIN) and the second control voltage (VIP).