Bias circuit and a bias generator circuit comprising such a bias circuit. The bias circuit (10, 11) comprises a switched capacitor resistor circuitry (C1, C2, M12-M17), and an operational amplifier (M1-M4, M10) with an input differential transistor pair (M1, M2). The bias circuit further comprises additional source follower transistors (M5, M6) associated with the first and second input differential transistors (M1, M2). The bias generator circuit has a PMOS switched capacitor reference circuit (11) and a NMOS switched capacitor reference circuit (10) and a transconductor reference cell (15). The transconductor reference cell (15) is a replica of a basic reference cell used in a further circuit.