| 摘要 |
PROBLEM TO BE SOLVED: To obtain the band split amplifier circuit by which low distortion amplification is conducted by maximizing the effect of amplification of signals at each split band. SOLUTION: A low frequency component passing through a low pass filter 17 is subtracted from an input signal to cancel distortion. Furthermore, a high frequency component passing through a high pass filter 23 is subtracted from the input signal to cancel distortion. Moreover, 1st and 2nd preamplifiers 16, 22 are used to match an output impedance of a photo diode 12 and an input impedance of each filter. After low and high frequency signals are individually amplified by the amplifiers 21, 26 and the resulting signals are combined by a coupling circuit, which provides an output. A steep cut-off characteristic is obtained by feeding back negatively an output of each filter, the frequency bands are split almost completely and low distortion amplification is attained. Furthermore, the frequency characteristic within the pass band of each filter is made flat by impedance matching and low distortion is enhanced. |
