| 摘要 |
PURPOSE:To completely cancell a phenomenon of stepped signal potentials, by detecting the frequency component a half of a horizontal scanning frequency and constituting a negative feedback loop, through the provision of a sampling hold circuit of an output pedestal potential in the porality inversion and non-inversion amplifier. CONSTITUTION:An input signal (a) amplified at an input amplifier 1 is inverted and non-inverted for the polarity with switches 2, 3 and an output amplifier 4, and the pedestal potential of an output signal (d) is stored in a sample hold circuit 13. In this case, if there is an inversion error, a rectangular wave of 1/2 frequency is outputted at the output of the circuit 13. The rectangular wave passes through a band pass filter 15, the output is applied to a rectifier 16, and the output of the rectifier 16 is applied to a switcher 19 via an amplifier 17. The output of the amplifier 17 is inverted at an inverting amplifier 18 and applied to the switch 19. An output signal (d) of the amplifier 4 is stored in a sampling hold circuit 10 in a pulse (f), this output is compared with a reference voltage 12 at a voltage comparator 11, the switch 19 is switched with the output of the comparator 11, the polarity of rectified output is fed back to the amplifier 1 to completely cancel the step. |
