| 摘要 |
PURPOSE:To make input impedance constant within a specified frequency band in a circuit that takes out a signal of specified frequency by connecting an element that constitutes a reverse circuit of input impedance in parallel to an input terminal of the circuit. CONSTITUTION:A tuning circuit of high Q tuned to a sound carrier is constituted of capacitors C12, C13, C14 and a coil L8, and a trap circuit of high Q tuned to a video carrier of adjoining channels is constituted of capacitors C10, C11 and L7. A series circuit of a coil L10 that constitutes an inverse circuit of input impedance of above-mentioned circuit and a resistance R20 is connected to a terminal 21. Such constitution can be expressed by an equivalent circuit separately shown. In this circuit, an inserted element is selected to satisfy specified conditions, and input impedance is made to a fixed value irrespective of frequency. |
