Methods and apparatus for generating a frequency comb and for its use in analyzing materials and in telecommunications. The level shifter can enhance the levels of a first and second clock signals, and output a first and a second control signal corresponding to the enhanced signals. The deposited layer preferably is a molybdenum containing alloy including about 50 atomic percent or more molybdenum, 0. These values are used to efficiently index locations within one or more data packets, such that processing performance is improved. A headphone that can be thinned while suppressing lowering of the attachment property is provided.