Bandgap reference circuit for producing fixed reference signals

A circuit, comprising:

• a start-up circuit;
• a load circuit;
• and
• a reference circuit coupled to the start-up circuit and the load circuit and
• configurable to provide a reference current to the load circuit;
• wherein the reference circuit comprises:
• a first transistor;
• a second transistor;
• a first resistor;
• a second resistor;
• a third resistor;
• and
• an operational amplifier including a positive input terminal and a negative input terminal;
• wherein the first transistor includes a current path terminal, and a control terminal coupled to an output of the operational amplifier;
• wherein the first resistor includes a first terminal coupled to the current path terminal of the first transistor, and a second terminal coupled to the positive input terminal of the operational amplifier;
• wherein the second resistor includes a first terminal coupled to the current path terminal of the first transistor, and a second terminal coupled to the negative input terminal of the operational amplifier;
• wherein the second transistor includes a current path terminal coupled to the negative input terminal of the operational amplifier, and a control terminal coupled to the current path terminal of the second transistor;
• and
• wherein the third resistor includes a first terminal coupled to the positive input terminal of the operational amplifier, and a second terminal coupled to a ground terminal.

A reference circuit, comprising:

• a first transistor;
• a second transistor;
• a first resistor;
• a second resistor;
• a variable resistor;
• and
• an operational amplifier;
• wherein the first transistor includes a current path terminal, and a control terminal coupled to an output of the operational amplifier;
• wherein the first resistor includes a first terminal coupled to the current path terminal of the first transistor, and a second terminal coupled to the operational amplifier;
• wherein the second resistor includes a first terminal coupled to the current path terminal of the first transistor, and a second terminal coupled to the operational amplifier;
• wherein the second transistor includes a current path terminal coupled to the operational amplifier, and a control terminal coupled to the current path terminal of the second transistor;
• and
• wherein the variable resistor includes a first terminal coupled to the operational amplifier, and a second terminal coupled to a ground node, and is configurable to control a first current through the first resistor and a second current through the second resistor.