| 摘要 |
<p>A switching circuit for connecting transceivers (TX, TX') for different frequencies alternatively to a common antenna (1). Each frequency disposes of a set comprising a plurality of PIN diodes (D1, D2; D1', D2') connected in series, and the PIN diodes in a set may be activated by a DC current (from VC1), which DC current is led through a bias resistor (3), creating a bias voltage. This bias voltage is used for reverse biasing the PIN diodes in another set, thus eliminating quiescent PIN diodes therein from creating spurious signals. The circuit is particularly suited for cellular mobile telephones using two frequency bands.</p> |
