| 摘要 |
PURPOSE:To obtain a circuit having a characteristic of a low center frequency and linear phase by means of a few number of transversal filters by connecting a linear phase emphasis circuit of middle/high frequencies comprising the transversal filter and a low frequency emphasis circuit in cascade. CONSTITUTION:The input signal is fed to a low frequency pre-emphasis circuit 2 having a gain-frequency characteristic whose center frequency is several hundreds kHz and comprising an operational amplifier circuit 2a. The output side of the low frequency pre-emphasis circuit 2 is connected to an output terminal 6 via a middle/high frequency linear phase pre-emphasis circuit 1 whose center frequency is 1MHz. The circuit 1 consists of seven taps symmetrical transversal filter. In selecting weighting coefficients a0, a1-a3, the gain-frequency characteristic shown in figure B is obtained. Then the pre-emphasis circuit device whose center frequency is as low as several hundreds kHz with a broad band and an object gain-frequency characteristic is obtained. In this case, since the peak value for pre-shoot and overshoot made equal is nearly realized, the phase of the circuit 2 is comparatively made linear.
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