US Patent 8941959 ESD protection apparatus

An electrostatic discharge (ESD) protection structure comprises a first NPN transistor and a second NPN transistor connected in parallel. The bases of the first NPN transistor and the second NPN transistor are coupled together and further coupled to a first voltage potential and a second voltage potential through two deep trench capacitors respectively. The ESD protection structure further comprises a third deep trench capacitor and a fourth deep trench capacitor coupled between the first voltage potential and the second voltage potential.