| 摘要 |
PURPOSE: To improve the performance of a comb-line filter and an SSB generating circuit or the like at a low cost with comparatively simple configuration by providing a difference between phase characteristics of two all-pass filters exhibiting an individual phase characteristic. CONSTITUTION: All-pass filters APF1, APF2 are a kind of active filters and transmit an input signal Vin at a prescribed gain and shift the phase of the input signal. The AFP1 has a phase characteristic a1 (=1/R1.C1) and the AFP2 has a phase characteristic a2 (=1/R2.C2). The APF1 having the phase characteristic a1 applies a phase shift of -π/4 at an angular frequencyω=a1 to the signal Vin as an output voltage signal V1 propagating through a signal path 1. Furthermore, the APF2 having the phase characteristic a2 applies a phase shift of -π/4 at an angular frequencyω=a2 to the signal Vin as an output voltage signal V2 transmitting through a signal path 2. When the phase characteristic is selected to be a1<a2, a phase difference between the signals V1, V2 becomes a prescribed value.
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