A filter network , comprising: an amplifier having an input and an output; a passive filter coupled to the output of the amplifier and configured to add at least one pole to a transfer function of the filter network; a voltage buffer having an input coupled to the passive filter and an output ; a resistor coupled between the output of the voltage buffer and the input of the amplifier ; a capacitor coupled between the output of the amplifier and the input of the amplifier ; and a circuit package housing at least the amplifier , the passive filter , and the voltage buffer ; characterized in that the voltage buffer comprises: a first current source connected between a supply voltage (Vs) and a first node: a first transistor , having a gate terminal connected to the input of the voltage buffer, a drain terminal connected to the first node, and a source terminal connected to the output of the voltage buffer; a second transistor , having a gate terminal connected to a second node, a drain terminal connected to the output of the voltage buffer, and a source terminal connected to a reference potential; a third transistor , having a gate terminal operable to receive a bias voltage, a drain terminal connected to the second node, and a source terminal connected to the first node; and a second current source connected between the second node and the reference potential. an amplifier having an input and an output; a passive filter coupled to the output of the amplifier and configured to add at least one pole to a transfer function of the filter network; a voltage buffer having an input coupled to the passive filter and an output ; a resistor coupled between the output of the voltage buffer and the input of the amplifier ; a capacitor coupled between the output of the amplifier and the input of the amplifier ; and a circuit package housing at least the amplifier , the passive filter , and the voltage buffer ; characterized in that the voltage buffer comprises: a first current source connected between a supply voltage (Vs) and a first node: a first transistor , having a gate terminal connected to the input of the voltage buffer, a drain terminal connected to the first node, and a source terminal connected to the output of the voltage buffer; a second transistor , having a gate terminal connected to a second node, a drain terminal connected to the output of the voltage buffer, and a source terminal connected to a reference potential; a third transistor , having a gate terminal operable to receive a bias voltage, a drain terminal connected to the second node, and a source terminal connected to the first node; and a second current source connected between the second node and the reference potential. a first transistor , having a gate terminal connected to the input of the voltage buffer, a drain terminal connected to the first node, and a source terminal connected to the output of the voltage buffer; a second transistor , having a gate terminal connected to a second node, a drain terminal connected to the output of the voltage buffer, and a source terminal connected to a reference potential; a third transistor , having a gate terminal operable to receive a bias voltage, a drain terminal connected to the second node, and a source terminal connected to the first node; and a second current source connected between the second node and the reference potential. <EOS>