START-UP CIRCUITS

A start-up circuit (2) arranged to initialise a circuit portion (4) with a zero stable point (200) and a non-zero stable point (202). The start-up circuit comprises: a capacitive voltage divider including a first capacitor (16) and a second capacitor (18) that generate a divider bias voltage at a divider node (48); a differential amplifier including first and second amplifier inputs (20, 22) and an amplifier output connected to the divider node; a first driver transistor (12) with its gate terminal connected to the divider node, and its drain terminal connected to a first start-up output and the first amplifier input; and a second driver transistor (14) with its gate terminal connected to the divider node, and its drain terminal connected to a second start-up output and the second amplifier input. The differential amplifier controls the divider bias voltage and drives the circuit portion to the non-zero stable point.