| 摘要 |
PURPOSE:To make circuit integration for a filter circuit, by picking up a low-pass output or a sampling output of input signal at a capacitor, through the switching of a constant current of a constant current source. CONSTITUTION:When a transistor (TR) Q7 is always turned off, a signal current flows through TRs Q1, Q2 and a signal current alfo flows through TRs Q4, Q5. When a pulse P1 is fed to a TR Q7 from a pulse generating circuit 1, the TR Q7 is switched on or off in synchronizing with the pulse P1 and the collector current 2I of a TR Q3 is switched on or off in synchronizing with the pulse P1, allowing to multiply the cut-off frequency by a factor of K, resulting in being lower. |
