A band-gap reference circuit includes a proportioned current generating circuit, a startup circuit, a current mirror circuit, a high-order temperature compensation generating circuit and a reference generating circuit. The mobile communication apparatus includes a communication module and a processing module. The dummy pattern is formed on the insulating layer to suppress a bending of the insulating layer. An input is provided for a signal for updating the visual display; and an update agent, such as a power source, is provided for operating the visual display in response to the input signal, such that the visual display comprises an updated persistent visual display label. These methods and apparatus include broadband and multi-band techniques for speech detection, estimation of near-end transmission path attenuation, and estimation of far-end transmission path attenuation and delay.