Bandgap reference with input amplifier for noise reduction

A bandgap reference circuit, comprising:

• a first bipolar junction transistor (BJT) having a first emitter, a first base, and a first collector, the first base shorted to the first collector;
• a second BJT coupled to the first BJT via a first resistor, the second BJT having a second emitter, a second base, and a second collector;
• a third BJT coupled to the first BJT, the third BJT having a third emitter, a third base, and a third collector, the third base coupled to the first base, and the third collector coupled to the first collector;
• a fourth BJT coupled to the third BJT, the fourth BJT having a fourth emitter, a fourth base, and a fourth collector, the fourth base shorted to the fourth collector, and the fourth base coupled to the second base;
• a second resistor coupled to the fourth emitter;
• a third resistor coupled to the first and third collectors;
• and
• an operational amplifier having a first input coupled to the first resistor and the second collector, a second input coupled to the third emitter and the fourth collector, and an output coupled to the second emitter and to the second resistor.