An amplifier includes an input stage with one or more input terminals for receiving a signal to be amplified, and an output terminal. An inverting gain stage includes an input terminal connected to the output terminal of the input stage, an output terminal for delivering an amplified signal, and a variable feedback resistor connected between the output terminal and input terminal thereof. The input stage is a transconductor stage biased by a current source. A transconductance thereof is set by a resistor of the current source so that the amplifier has a gain proportional to the product of the variable feedback resistor multiplied by the transconductance.
展开▼