Patent ID: 11296665

Abstract:
For converting analog audio signals captured by a microphone into digital audio data, the analog audio signals are first amplified in a pre-amplifier and then fed to an analog-to-digital converter (ADC). For better utilizing the dynamic range of the ADC, a DC coupled dual amplifier circuit may be used herein that automatically switches between two amplifier branches with different gain factors. To avoid switching noise, both signals must have the same DC component before the analog-to-digital conversion. To achieve this, the amplifier arrangement comprises a first amplifier branch having a higher first gain factor (G1) and providing a first output voltage (VOUT1) and a second amplifier branch having a lower second gain factor (G2) and providing a second output voltage (VOUT2). Both amplifier branches are DC coupled and receive as a common input signal an audio signal with a predetermined DC component (Vk). The amplifier arrangement further comprises a differentiating member (D) for generating a voltage difference between the two output voltages (VOUT1,VOUT2). From the voltage difference, a control voltage (Vbias) is generated for controlling the DC component (Vk) of the input signal such that the DC components of the output voltages (VOUT1, VOUT2) are aligned to each other.