The hinging device for pivotably attaching the links of a bracelet includes a bar comprising at at least one of its ends a hole provided with an inner thread, and a screw whose thread is engaged in said inner thread. In one embodiment, a power amplifier system includes a plurality of power amplifiers and an envelope tracking module for generating a supply voltage for the power amplifiers. At this time, the dot patterns are prepared to be different from each other for M times of scans in a multi-pass print of M passes.