US 7,321,256 B1 | ||
Highly reliable and zero static current start-up circuits | ||
Narasimhan Vasudevan, Los Angeles, Calif. (US) | ||
Assigned to Xilinx, Inc., San Jose, Calif. (US) | ||
Filed on Oct. 18, 2005, as Appl. No. 11/252,679. | ||
Int. Cl. G05F 3/04 (2006.01) |
U.S. Cl. 327—539 [323/313] | 15 Claims |
1. A circuit for generating a bandgap reference voltage for an integrated circuit (IC) device, the circuit comprising:
a bandgap circuit including an op-amp coupled to a resistor network, wherein the bandgap circuit is configured to maintain
the bandgap reference voltage at a specified level;
a start-up circuit having an output coupled to the resistor network, wherein upon power-on of the device the start-up circuit
turns on and provides a start-up current to initialize the bandgap circuit to a valid state, and when the bandgap circuit
enters the valid state, the start-up circuit turns off and reduces the start-up current to a negligible level; and
a recovery circuit having an output coupled to the resistor network, wherein if the bandgap circuit enters an invalid state,
the recovery circuit turns on and provides a recovery current to the bandgap circuit to return the bandgap circuit to the
valid state,
wherein the recovery current is different from the start-up current, and
wherein the start-up circuit comprises:
a first PMOS transistor coupled between a voltage supply and a control node, and having a gate to receive the bandgap reference
voltage;
a first NMOS transistor coupled between the control node and ground potential, and having a gate to receive the bandgap reference
voltage; and
a source-follower circuit coupled between the voltage supply and the resistor network and having a control terminal coupled
to the control node.
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