US 6,720,755 B1 · Band gap reference circuit

Abstract

A band gap reference includes circuitry providing a reference voltage (VDIODE) at 1.0 volt or below to provide a stable reference for 1.3 volt or lower circuits, which would otherwise not function accurately with a typical band gap reference of 1.2 volts. The band gap reference includes an op-amp equally driving the gate of various current source transistors. A first current source drives a BJT transistor connected in a diode fashion, while a second current source drives a further diode connected BJT transistor through a resistor. An output VDIODE is provided from a further resistor connected to two additional current sources. The first of these current sources is driven by the op-amp output to increase output with temperature, while the second of these current sources is driven by a replicating op-amp connected to a resistor providing current decreasing with temperature, both current sources functioning to provide a stable low voltage VDIODE on the resistor with variations in temperature and supply voltage.

Claims14

Dependent claims

A band gap reference comprising:

a first amplifier having a (+) input, a (−) input and an output;
a first current source having a current control input connected to the output of the first amplifier, the first current source connected to the (+) input of the first amplifier;
a first diode connecting the first current source to a ground line;
a second current source having a current control input connected to the output of the first amplifier, the second current source connected to the (−) input of the first amplifier;
a first resistor having a first terminal connected to the second current source and the (−) input of the first amplifier, and having a second terminal;
a second diode connecting the second terminal of the first resistor to the ground line;
a second resistor;
and
means for adjusting current based on temperature variations, the means for adjusting being connected to the output of the first amplifier and the second resistor, and providing an output which minimizes current change due to temperature variations by combining the output from the first amplifier with current provided through the second resistor.

6 more elements

A current reference comprising:

a first amplifier having an input, and an output;
a first current source having a current control input connected to the output of the first amplifier;
a first diode connecting the first current source to a ground line;
a second current source having a current control input connected to the output of the first amplifier;
a first resistor having a first terminal connected to the second current source, and the input of the first amplifier, and having a second terminal;
a second diode connecting the second terminal of the first resistor to a ground line;
a second amplifier having an first input connected to the first terminal of the first resistor, and having an output;
a third current source having a current control input connected to the output of the second amplifier;
a second resistor having a first terminal connected to the third current source, and a second input of the second amplifier;
a fourth current source having a current control input connected to the output of the first amplifier, and having an output forming an output for the current reference;
and
a fifth current source having a current control input connected to the output of the second amplifier, and an output connected to the output of the current reference.

9 more elements

A band gap reference comprising:

an operational amplifier (opamp) having a (+) input, a (−) input and an output;
a first diode connected transistor having a first terminal connected to a ground line and having a second terminal;
a first current source transistor having a source-drain path with a first terminal connected to a power supply terminal and a second terminal, and having a gate connected to the output of the opamp;
a first gating transistor having a source-drain path coupling the second terminal of the first current source transistor to the second terminal of the first diode connected transistor, and having a gate;
a second diode connected transistor having a first terminal connected to the ground line, and having a second terminal;
a first resistor having a first terminal connected to the second terminal of the second diode connected transistor, and having a second terminal connected to the (−) input of the opamp;
a second current source transistor having a source-drain path with a first terminal connected to the power supply terminal and a second terminal, and having a gate connected to the output of the opamp;
a second gating transistor having a source-drain path coupling the second terminal of the second current source transistor to the second terminal of the first resistor, and having a gate connected to the gate of the first gating transistor;
a third current source transistor having a source-drain path with a first terminal connected to the power supply terminal, and a gate connected to the output of the op-amp;
and
a third gating transistor having a source-drain path with a first terminal connected to a second terminal of the third current source transistor, a second terminal forming a reference node (VBSNRF), and having a gate connected to the gate of the first and second gating transistors.

8 more elements

Dependencies are inferred from the claim text.

Band gap reference circuit

Life of this patent

Band gap reference circuit

Life of this patent

Abstract

Claims14