Band gap reference using a low voltage power supply

A band gap reference comprising:

• an operational amplifier (opamp) having a (+) input, a (-) input, and an output, the opamp comprising:
• a first transistor (524) having a gate forming the (+) input of the opamp;
• a second transistor (525) having a gate forming the (-) input of the opamp, and a source to drain path connected on a first end to a first end of the source to drain path of the first transistor (524);
• and
• a current mirror comprising:
• a third transistor (521) having a source to drain path coupling V.sub.DD to a second end of the source to drain path of the first transistor (524), and having a gate;
• and
• a fourth transistor (522) having a source to drain path coupling V.sub.DD to a second end of the source to drain path of the second transistor (525), and having a gate coupled to the gate of the third transistor (521);
• a current sink having a first terminal coupled to V.sub.SS, and a second terminal coupled to the first end of the source to drain path of the first transistor (524) and the second transistor (525);
• a first bipolar transistor (511) having an emitter to collector path coupling the (+) input of the opamp to V.sub.SS, and a base coupled to the second terminal of the current sink;
• a first current source transistor (501) having a source to drain path coupling V.sub.DD to the (+) input of the opamp, and having a gate coupled to the output of the opamp;
• a first resistor (R.sub.1) having a first terminal coupled to the (-) input of the opamp, and a second terminal;
• a second bipolar transistor (512) having an emitter to collector path coupling the second terminal of the first resistor (R.sub.1) to V.sub.SS, and a base coupled to the base of the first bipolar transistor (511);
• a second current source transistor (502) having a source to drain path coupling V.sub.DD to the (-) input of the opamp, and having a gate coupled to the output of the opamp;
• a second resistor (R.sub.2) having a first terminal forming the output of the band gap reference, and a second terminal;
• a third bipolar transistor (513) having an emitter to collector path coupling the second terminal of the second resistor (R.sub.2) to V.sub.SS, and having a base coupled to V.sub.SS ;
• and
• a third current source transistor (503) having a source to drain path coupling V.sub.DD to the output of the band gap reference, and having a gate coupled to the output of the opamp.

A band gap reference comprising:

• an operational amplifier (opamp) having a (+) input, a (-) input, and an output, the opamp comprising:
• a first transistor (524) having a gate forming the (+) input of the opamp;
• a second transistor (525) having a gate forming the (-) input of the opamp, and a source to drain path connected on a first end to a first end of the source to drain path of the first transistor (524);
• and
• a current mirror comprising:
• a third transistor (521) having a source to drain path coupling V.sub.DD to a second end of the source to drain path of the first transistor (524), and having a gate;
• and
• a fourth transistor (522) having a source to drain path coupling V.sub.DD to a second end of the source to drain path of the second transistor (525), and having a gate coupled to the gate of the third transistor (521);
• a first resistor (Rn) having a first terminal coupled to V.sub.SS and a second terminal coupled to the first end of the source to drain path of the first transistor (524);
• a fifth transistor (528) having a source to drain path with a first end coupled to the second terminal of the first resistor (Rn), a second terminal, and having a gate coupled to the (+) input of the opamp;
• a first bipolar transistor (511) having an emitter to collector path coupling the (+) input of the opamp to V.sub.SS, and a base coupled to the second end of the source to drain path of the fifth transistor (528);
• a first current source transistor (501) having a source to drain path coupling V.sub.DD to the (+) input of the opamp, and having a gate coupled to the output of the opamp;
• a second resistor (R.sub.1) having a first terminal coupled to the (-) input of the opamp, and a second terminal;
• a second bipolar transistor (512) having an emitter to collector path coupling the second terminal of the second resistor (R.sub.1) to V.sub.SS, and a base coupled to the base of the first bipolar transistor (511);
• a second current source transistor (502) having a source to drain path coupling V.sub.DD to the (-) input of the opamp, and having a gate coupled to the output of the opamp;
• a third resistor (R.sub.2) having a first terminal forming the output of the band gap reference, and a second terminal;
• a third bipolar transistor (513) having an emitter to collector path coupling the second terminal of the third resistor (R.sub.2) to V.sub.SS, and having a base coupled to V.sub.SS ;
• and
• a third current source transistor (503) having a source to drain path coupling V.sub.DD to the output of the band gap reference, and having a gate coupled to the output of the opamp.