Band-pass filter

A band-pass filter comprising:

• a first first-order filter stage comprising a first resistor characterised by a first impedance and connected to a first node, referred to as a filter input node, and, through a second node, to a first reactive component connected to a third node, the first impedance being such that a first current therethrough is dependent on the difference between the voltages at the first and second nodes when the first current flows from the first node to the second node;
• a second first-order filter stage comprising a second resistor characterised by a second impedance and connected to the second node, and, through a fourth node, to a second reactive component connected to a fifth node, the second impedance being such that a second current therethrough is dependent on the negative of the sum of the voltages at the second and fourth nodes when the second current flows from the second node to the fourth node;
• and
• a summing element for summing the voltages at the second and fourth nodes to output a voltage at a sixth node.