Amplifier circuit with reference circuit derived from input signal and correction signal from reference current, and filter capacitance current

摘要

An amplifier circuit (11) for amplifying electric signals, comprising controllable switching means (2) for generating a block wave signal whose amplitude varies between first and second supply voltage values during operation, filter means (9) for filtering the block wave signal so as to produce an output signal (10). The filter means (9) comprise a self-inductance (16) and a capacitance (17). The amplifier circuit (11) furthermore comprises modulating means (3) for pulse width modulation of the block wave signal by driving the switching means (2) in response to an input signal (16) to be amplified, and correction means (12) for providing from a reference value (U¿ref) derived from the input signal and an output signal value proportional to the output signal (10) a correction signal for controlling the modulating means (3). In order to correct for interferences in the output signal (10), means (13) are provided for deriving a reference current (I¿ref) from the input signal (6) as well as means (8) for providing a filter capacitance current proportional to the current through the filter capacitance (17). The correction means (12) are arranged for providing a current correction signal from the reference current (I¿ref) and the filter capacitance current (18).