A biosignal apparatus, comprising: an amplifier configured to alternate between an operating state and a low power state based on a periodically changing control signal; and a sampler configured to sample a signal output from the amplifier in response to the amplifier being in the operating state and maintain the sampled signal in response to the amplifier being in the low power state, wherein the sampled signal is fed back to the amplifier characterized in that the amplifier comprises: a transconductance, TC, input terminal configured to convert and amplify a modulated input voltage to a current; a transimpedance, TI, output terminal configured to convert and amplify a current to an output voltage; a first direct current servo loop, DSL,; a second DSL; a first sample and hold circuit configured to perform sampling and hold of an output voltage at the TC input terminal; and a second sample and hold circuit configured to perform sampling and hold of an output voltage at the TI output terminal, wherein the first DSL is configured to feed back the output voltage of the second sample and hold circuit to the TC input terminal, and wherein the second DSL is configured to feed back the output voltage of the third sample and hold circuit to the TC input terminal. an amplifier configured to alternate between an operating state and a low power state based on a periodically changing control signal; and a sampler configured to sample a signal output from the amplifier in response to the amplifier being in the operating state and maintain the sampled signal in response to the amplifier being in the low power state, wherein the sampled signal is fed back to the amplifier characterized in that the amplifier comprises: a transconductance, TC, input terminal configured to convert and amplify a modulated input voltage to a current; a transimpedance, TI, output terminal configured to convert and amplify a current to an output voltage; a first direct current servo loop, DSL,; a second DSL; a first sample and hold circuit configured to perform sampling and hold of an output voltage at the TC input terminal; and a second sample and hold circuit configured to perform sampling and hold of an output voltage at the TI output terminal, wherein the first DSL is configured to feed back the output voltage of the second sample and hold circuit to the TC input terminal, and wherein the second DSL is configured to feed back the output voltage of the third sample and hold circuit to the TC input terminal. a transconductance, TC, input terminal configured to convert and amplify a modulated input voltage to a current; a transimpedance, TI, output terminal configured to convert and amplify a current to an output voltage; a first direct current servo loop, DSL,; a second DSL; a first sample and hold circuit configured to perform sampling and hold of an output voltage at the TC input terminal; and a second sample and hold circuit configured to perform sampling and hold of an output voltage at the TI output terminal, wherein the first DSL is configured to feed back the output voltage of the second sample and hold circuit to the TC input terminal, and wherein the second DSL is configured to feed back the output voltage of the third sample and hold circuit to the TC input terminal.