There is described a low-corner frequency high pass filter circuit comprising: an operational amplifier (12) having an inverting input (14), a non-inverting input (24) and an ouput (22), a series capacitor (26) having a first end connected to the non-inverting input (24) of the operational amplifier (12) and a second end connected to an input signal (Vin, 28), a first resistor (16) having a first end connected to the inverting input (14) of the operational amplifier (12) and a second end connected to a reference potential, a feedback resistor (20) having a first end connected to the inverting input (14) of the operational amplifier (12) and a second end connected to the output (22) of the differential amplifier (12), and a low gain amplifier circuit (30) having a first input connected to the reference voltage, a second input connected to the output (22) of the operational amplifier (12) and an output (32) connected to the non-inverting input (24) of the operational amplifier (12).