A system and method for improving the prompt dose radiation response of mixed-signal integrated circuits is disclosed. An internal analog circuit inside a mixed-signal integrated circuit generates an internal analog reference voltage that has been used for various purposes in the integrated circuit. At least one external capacitor is added either internal or external to a device package of the integrated circuit. The external capacitor reduces any change in the internal reference voltage due to prompt dose radiation by stabilizing the internal reference voltage and thus improves prompt dose radiation response of mixed-signal integrated circuits. A much greater value of capacitance may be provided without increase in dielectric rupture suceptability or decrease in manufacturing yield which may be associated with added on-chip capacitance. This increased capacitance primarily reduce the amount of disturbance caused to the internal node during a prompt dose radiation event.