| 摘要 |
<p>PURPOSE:To obtain a high-quality picture by inserting a filter, which eliminates a switching noise, to a power supply line of an analog circuit in a personal computer where the analog circuit and digital circuit share a common operating power source. CONSTITUTION:A low-pass filter 40 is inserted between a power supply part 30 and an analog circuit (composite circuit) 20 and prevents the switching noise, which is generated from a processor part 10 using the same power supply part 30, from inputting the analog circuit 20 through a power supply line 31. Individual TTL-level logical signals outputted to signal lines 11-14 of the processor part 10 are synthesized by resistances R1-R4 of the circuit 20, and the output signal is converted to an analog signal and is impressed to the base of a transistor TRQ1. The voltage drop between the base and the emitter of the TRQ1 is outputted as an emitter output to an output terminal OUT as it is. By this constitution, the switching noise is prevented from coming around to the analog circuit to output stable high-quality pictures, sounds, etc.</p> |
