Bandgap Reference

To avoid noise on the output, you just need to filter your power source ! Bandgap references are described as critical analog designs, so you need to do everything you can to protect this part of your circuit. We often put capacitors in parallel of the main power source to reduce noise on internal references of ICs. It’s the circuit designer to do the job for you :) The cascode technique is a good application. You will often see cascode in current mirrors to compensate the L modulation and most importantly to compensate your process fluctuation once you will produce your chip.

@blob Thank you for your response !

Can you please explain how this circuit works?

Ima little confused but cool

@PatrickJoseph This circuit has 2 parts. The first one is the floating mirror on the left. The pack of current mirror garantee the voltage at the collector of the diode connected PNP to be equal. This will generate PTAT current I = thermal voltage * ln(6) / 47 kohm. **(ln(6) cannot be used in every circuit. It depends on circuit) topology. This current is power supply independent. The second part (on the most left side) is for generating supply indepentdent voltage by using PTAT curent mentioned earlier. The equation is Vref = Vbe(most left diode connected PNP) + (PTAT current*690 kohm). This voltage is the supply independent voltage. You can change 5V to 6 7 8 V ... and so on. This voltage will be constant at 1.23 V. Sorry for the late. I am not so confident to explain it that it took me many weeks to read more about it. If I mention something wrong, please, tell me :)