CIRCUIT, SYSTEM AND METHOD FOR ISOLATING A TRANSDUCER FROM AN AMPLIFIER IN AN ELECTRONIC DEVICE

摘要

A circuit, device and method for controlling an output signal of an amplifier are provided. The output signal may be controlled through a first stage located before a digital to analog converter and / or a second stage located after it. The first stage boosts the digital signal to match with the full signal range of the converter. For the second stage, the circuit comprises: a first resistor coupled to an output of the amplifier in series, the first resistor having a resistance value Rs; a second resistor coupled to the first resistor in series, the second resistor having a resistance value Rp; and an output terminal for a transducer connected to the electronic device, the output terminal connected in parallel to the second resistor. In the circuit, the resistance values Rs and Rp are related by an inversely proportional relationship. The circuit provides an output signal at the output terminal having a noise floor that varies with an output level of the amplifier and a constant output impedance as seen from the transducer.