| 摘要 |
PURPOSE:To reduce variation depending upon whether the boost quantity of a frequency band to be increased by providing a level adjusting circuit which adjusts an input signal, a low-pass filter circuit which cuts off its output signal at some specific angular frequency omega0, a band-pass filter circuit which equalizes the center angular frequency of the output signal almost to the angular frequency omega0, and the 1st adding circuit which sums up signals of respective circuits. CONSTITUTION:The 1st adding circuit 44 sums up signals obtained by multiply ing output signals of the band-pass filter circuit and low-pass filter circuit 31 by a proper constant alpha, signals obtained by multiplying them by a constant betadetermined properly by using the constant alpha, and an input signal to an input terminal 10. A low frequency range adjusting circuit increases the low frequency range and the angular frequency omega1 at the start of the increase is determined unequivocally depending upon omega1=omegao.(1+alpha)<nu2> an angular frequency omega0 deter mined unequivocally during the increase, and constant alpha determining the boost quantity, so a variable adjustment of the low frequency range is made while its frequency band is held constant. |
