Inside the 8086 processor, tiny charge pumps create a negative voltage
http://www.righto.com/2020/07/inside-8086-processor-tiny-charge-pumps.html [www.righto.com]
2020-07-26 21:25
You might wonder how a charge pump can turn a positive voltage into a negative voltage. The trick is a “flying” capacitor, as shown below. On the left, the capacitor is charged to 5 volts. Now, disconnect the capacitor and connect the positive side to ground. The capacitor still has its 5-volt charge, so now the low side must be at -5 volts. By rapidly switching the capacitor between the two states, the charge pump produces a negative voltage.