pcb设计的100条规则(编辑修改稿)

pcb设计的100条规则(编辑修改稿)内容摘要：

ust spend $3000. Are you smart enough to figure out how to use a $.30 op amp instead? 3 The Q of an LC tank circuit is dominated by the losses in the inductor in terms of series R. Q=3 Leakage current doubles for every 10degC increase in temp. 3 When inputs to most JFET op amps exceed the monmode range for the part, the output may reverse polarity. This artifact will haunt the designers of these parts for the rest of their lives, as it should! 3 Understand the difference between makebeforebreak and breakbeforemake when you specify switches. 3 3 Terminal voltage regulators in the TO220 packages are wonderful parts. They are cheap, rugged, thermally protected and very versatile. Use them virtually any place where you need a protected power transistor. They also make nice AM powermodulators. 3 Use step recovery diode where you need fast edges under 100pS (hotcarrier is even faster) 3 The old 723 regulator is still one of the lowest noise regulators around! ( 100Hz10k) 3 You can make a very simple oscillator with one diac, cap and a resistor. 3 NPN transistors are normally superior to their PNP counterpart in performance. Typical spec in some databooks should read Seen it once. Always work with the worst spec of the part when doing a design. 4 Dont just copy circuits from application notes without understanding pletely how it operates, and the reason for the choice of values. 4 Dealing with crystals, make sure you understand the difference between series and parallel resonant. In a circuit, crystal frequency can generally be slightly lowered by placing a inductor in series and increased by a capacitor in series. 4 Power MOSFETS onresistance will have a ve temp coef and not +ve at low current levels. This is important to remember when paralleling devices. 4 Lowest noise figure of a RF transistor is not normally where the input is perfectly matched. 4 Many unstable RF devices can be made stable by loading the input or the output by a simple resistor, either in series or parallel. 4 You trade gain for bandwidth. 4 Pushpull power invertors using bipolars are risky and can saturate the core because of hysteresis stepping (use power fets) 4 The Al value of a core will increase up to 50% or more under current transients. 4 Be aware of leaka。