A circuit for improving process robustness of sub-threshold SRAM memory cells serves as an auxiliary circuit for a sub-threshold SRAM memory cell. In particular, embodiments address situations in which a receiver, designed to handle spread spectrum clocking, may not always or continuously encounter spread spectrum signals. The LED lamp is adapted to be powered by an external power source and includes an input power circuit receiving an input voltage from the external power source. The comparing circuit is configured to determine whether the amplified voltage is greater than a first predetermined value when the comparing circuit is coupled to the power supply unit.