| 摘要 |
A variable attenuator is provided, which includes at least one step attenuator circuit. The attenuator circuit includes at least a signal input end, a signal output end, a conjunct grounding end. The first cascade resistor is connected between the signal input end and the signal output end, and a main signal circuit is formed. The first parallel resistor is connected between a point of the main signal circuit and the conjunct grounding end. The attenuator further includes: the first parallel switch connected with the first cascade resistor; the first cascade switch connected with the first parallel resistor. The parallel switch is connected in parallel to the two ends of the cascade resistor in the variable attenuator, and the cascade switch is connected in series to the two ends of the parallel resistor. At the same time when the parallel switch is controlled to turn on to disable the certain step attenuation, the cascade switch is controlled to turn off to eliminate the influence to the main signal circuit by the parallel resistor. |
