| 摘要 |
A differential PIN diode attenuator (450) that selectively attenuates a differential analog input signal. The two parts of the differential signal are applied to separate input lines (452, 454) and are 180° out of phase with each other. One input line (452) is coupled to a first attenuation path (456) including a resistor and a first non-attenuation path (458) including a PIN diode (462). The other input line (454) is coupled to a second attenuation path (466) including a resistor and a second non-attenuation path (468) including a PIN diode (472). The diodes (462, 472) are biased by a DC bias signal so that the differential analog signal can bypass the attenuation paths (456, 466). The DC bias signal is applied halfway between the input lines (452, 454) where the two parts of the differential signal cancel. A shunt diode (490, 492,) and parallel shunt resistors are provided in combination with the attenuation resistor to allow it to have a relatively small value.
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