An instrumentation amplifier includes a first amplifier having one input connected to a first input of the instrumentation amplifier, a second amplifier having one input connected to a second input of the instrumentation amplifier, and a feedback network. The feedback network including an active filter having a first low pass filter characteristic with a first cut-off frequency in respect of differential mode signals at the first and second inputs of the instrumentation amplifier, and a second low pass filter characteristic with a second cut-off frequency in respect of common mode signals at the first and second inputs of the instrumentation amplifier. The disclosure also relates to a device for acquiring biopotential signals and a signal amplification method.