| 摘要 |
PURPOSE:To obtain an output with reduced secondary distortion by forming plural current paths of series-connected active elements corresponding to whether an input signal is positive or negative, and holding the AC resistance of the current paths unchanged without reference to the polarity of the input signal. CONSTITUTION:In an amplitude limiting circuit 1, NPN transistors (TR)Q and Q4 are connected in the same direction and NPNTRs Q2 and Q5 are connected in series in the opposite direction. When a positive, half-cycle input signal Vin is supplied, a current flows through the TRs Q and Q4 as shown by an arrow I1. The TRs Q and Q4 are therefore used in normal states and when the emitter resistance of the TRQ is re, the AC resistance of this current path is re+rcs. When a negative, half-cycle input signal Vin is applied, on the other hand, a current flows through the TRs Q2 and Q5 as shown by an arrow I2. At this time, when the emitter resistance of the TRQ2 is re, the AC resistance of this current path is re+rcs, which is the same as above. |
