Multi-band amplifier

摘要

The preferred embodiment of the invention provides a dual-band amplifying apparatus, particularly for use in a cellular telephone, in which first and second amplifying sections are electrically connected to each other at a common input and a common output. When the respective amplifier of one amplifying section is disabled, the disabled amplifying section is arranged to present an impedance at the common input and common output which is substantially open-circuit to signals in the frequency band of the other amplifying section. This arrangement eliminates the need to provide switching circuitry to isolate the amplifying sections. <IMAGE>