These drawbacks led to studying the use of high-frequency AC current to drive the discharge lamps. High-frequency operation not only results in significant ballast volume and weight reduction, but also improves the performance of the discharge lamp. Figure 5 shows the measured voltage and current waveforms of the lamp operating with the same current level but at high frequency. The voltage and current waveforms are almost proportional with the same v-i characteristic of a resistor, although this resistor is not linear and varies as a function of time and lamp current. The re-strike voltage peak no longer exists. The recombination of ions and electrons in the discharge is very low. No re-ignition energy is needed. The lamp electrodes also sustain the electron density during the transition from cathode to anode function, resulting in additional energy savings. Therefore, the gas discharge itself is more efficient in high-frequency operation, contributing to an increased efficacy. Figure 6 shows the curve of fluorescent lamp