| 摘要 |
PURPOSE:To obtain a slice signal having high accuracy by controlling the gain in response to the slice level. CONSTITUTION:A slicing circuit 16 is formed between a terminal T11 and an earth with resistances R21 and R22, a constant current source Q14, transistors Q11-Q13, Q31, Q32, etc. A current mirror circuit 21 is formed with a constant source Q25, TRQ21-Q24, etc., and at the same time a double balance type multiplying circuit 22 is formed with TRQ41, TRQ42 and a constant current source Q43, etc. Thus the gamma-compensated 5 luminance signal voltage Vy(Sy) is compared with the reference voltage VB and sliced 16 to produce a signal Ss. Therefore the variation of the signal Vy at a slice level VB becomes sharp and can be clearly sliced. In addition, the accuracy of the slice level can be improved since the signal is sliced by the comparison of voltage through TRQ11- Q13 without using the VBE of TR. |
