| 摘要 |
According to the invention a controllable passive circuit element including: a first terminal and a second terminal; a passive circuit control input to which a control signal is applied; a first passive circuit component having a first impedance type and a first impedance value; a second passive circuit component of the same type as the first passive circuit component, the second passive circuit component having the same impedance type as the first passive circuit component and a second impedance value different to the first impedance value of the first passive circuit component; and a control means for dithering the first passive circuit component and the second passive circuit component over a period of time in accordance with a control state derived from the control signal so as to produce an impedance between the first and second terminals with an effective time- averaged impedance value which lies at the first impedance value or second impedance value, or between the first impedance value and the second impedance value, dependent upon the control signal applied to the control circuit input. |
