| 摘要 |
A start-up circuit 2 initialises a circuit portion 4 having a zero stable point and a non-zero stable point (fig 1, 200, 202) and 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 that is connected to the output of a differential amplifier. Differential amplifier inputs 20,22 are connected to two start-up outputs at the drains of driver transistors 12,14 whose gates are also connected to the divider node 48. The differential amplifier controls the divider bias voltage and drives the circuit portion to the non-zero stable point. The differential amplifier can be a long tailed pair having differential n-channel metal-oxide semiconductor (NMOS) transistors 20,22 whose sources are connected to a current mirror current source 28; and p-channel metal-oxide semiconductor (PMOS) mirror transistors 26,24, one of which 26 is diode-connected, the drain of each mirror transistor being connected to the drain of a differential transistor. Circuit portion 4 having two stable points may be part of a bandgap reference circuit which produces a temperature-stable reference voltage at the non-zero stable point, an oscillator or a flip-flop. |
