The invention discloses a signal conditioning circuit having a vector demodulator for breaking down a signal applied to the input into a first component and a second component. The outputs of the vector demodulator having at least one first amplifier circuit comprising a first and a second input connected thereto which may be configured to amplify signals applied to the input using an adjustable gain. The outputs of the at least one first amplifier circuit are connected to a first analog/digital converter. A polyphase filter may be connected between outputs of the vector demodulator and the input of the first amplifier circuit. The polyphase filter has an adjustable filter bandwidth.