Low-pass filter circuit

A low-pass filter circuit comprising:

• a low-pass filter input terminal;
• a low-pass filter output terminal;
• a reference terminal;
• at least three filter resistors connected in series with each other between the low- pass filter input terminal and the low-pass filter output terminal, such that there is a resistor-connecting-node between each adjacent pair of filter resistors;
• a plurality of filter capacitors, one for each of the resistor-connecting-nodes, wherein each of the filter capacitors is connected between an associated resistor- connecting-node and the reference terminal;
• and
• a branch connected in parallel with the at least three filter resistors, wherein the branch comprises a bridging capacitor and a bridging resistor in series with each other;
• wherein the branch comprises:
• a bridging-connection-node between the series connection of the bridging capacitor and the bridging resistor;
• and
• a tuning resistor connected between the bridging-connection-node and the reference terminal, wherein the tuning resistor is a variable resistor.