A switching amplifier includes a level shifting circuit for adjusting a voltage level of an original input signal to generate a first input signal and a second input signal. The UE is configured to connect to both a wireless local area network and a wireless wide area network. Other amino acids can be added, provided that their sum is a percentage lower than 20 wt % with respect to the sum of the other active ingredients, and less than 10 wt % for each individual amino acid.