25年前，我在处理类似H8系列的器件，这些器件采用当时相当先进的工艺技术，使用1.0μm甚至0.8μm CMOS技术。今天的石英晶体振荡器器件使用更先进的工艺技术，我们RA微控制器系列的最新器件采用40纳米技术，线宽比我以前使用的H8小25倍。

随着最新器件中的晶体管尺寸变得更小，并且更重要的是，晶体管开关频率变得更快，噪声成为导致器件故障的一个越来越大的因素。遥遥领先Renesas Oscillator噪音来源.

在上图中，您可以看到使用旧技术的器件与最新器件之间的简单比较，前者的晶体管工作沟道长度为1μm，器件通常采用当时的快速8 MHz时钟工作，晶体管开关速度较慢，后者的晶体管沟道长度为40 nm，工作频率高达200 MHz或更高。

在这种情况下，您可以看到切换时间要快得多，对于最新的晶体振荡器设备，我们试图处理的信号可能比噪声信号更快。因此，随着我们向更小的工艺几何发展，噪声已经成为一个更大的问题。瑞萨在我们的设备上采取了许多措施，设计了有助于在这种环境下工作的功能，精心设计的电源电路和优化的I/O缓冲器以及专业保护电路，但尽可能将设计中的任何影响降至最低仍然非常重要，因为最终，如果噪声进入设备，就很难消除。

Mfr Part #	Mfr	Description	Series	Frequency	Output	Voltage - Supply
XLH738000.921600X	Renesas晶振	XTAL OSC XO 921.6000KHZ HCMOS	XL	921.6 kHz	HCMOS	3.3V
XLH336029.500000I	Renesas晶振	XTAL OSC XO 29.5000MHZ HCMOS SMD	XL	29.5 MHz	HCMOS	3.3V
XLH735015.360000I	Renesas晶振	XTAL OSC XO 15.3600MHZ HCMOS SMD	XL	15.36 MHz	HCMOS	3.3V
XLH736045.000000X	Renesas晶振	XTAL OSC XO 45.0000MHZ HCMOS SMD	XL	45 MHz	HCMOS	3.3V
XAH526033.300000I	Renesas晶振	XTAL OSC XO 33.3000MHZ LVCMOS	XA	33.3 MHz	LVCMOS	2.5V
XLH336013.330000I	Renesas晶振	XTAL OSC XO 13.3300MHZ LVCMOS	XL	13.33 MHz	LVCMOS	3.3V
XLH336037.125000I	Renesas晶振	XTAL OSC XO 37.1250MHZ LVCMOS	XL	37.125 MHz	LVCMOS	3.3V
XLH336002.048000I	Renesas晶振	XTAL OSC XO 2.0480MHZ LVCMOS SMD	XL	2.048 MHz	LVCMOS	3.3V
XLH336032.051655I	Renesas晶振	XTAL OSC XO 32.051655MHZ LVCMOS	XL	32.051655 MHz	LVCMOS	3.3V
XLH328033.333000X	Renesas晶振	XTAL OSC XO 33.3330MHZ LVCMOS	XL	33.333 MHz	LVCMOS	2.5V
XLH336033.330000I	Renesas晶振	XTAL OSC XO 33.3300MHZ LVCMOS	XL	33.33 MHz	LVCMOS	3.3V
XLH336031.948512I	Renesas晶振	XTAL OSC XO 31.948512MHZ LVCMOS	XL	31.948512 MHz	LVCMOS	3.3V
XLH336019.000000I	Renesas晶振	XTAL OSC XO 19.0000MHZ LVCMOS	XL	19 MHz	LVCMOS	3.3V
XLH730030.875520I	Renesas晶振	XTAL OSC XO 30.87552MHZ LVCMOS	XL	30.87552 MHz	LVCMOS	3.3V
XLH535003.686000I	Renesas晶振	XTAL OSC XO 3.6860MHZ LVCMOS SMD	XL	3.686 MHz	LVCMOS	3.3V
XLH736078.125000X	Renesas晶振	XTAL OSC XO 78.1250MHZ LVCMOS	XL	78.125 MHz	LVCMOS	3.3V
XLH736025.750000X	Renesas晶振	XTAL OSC XO 25.7500MHZ LVCMOS	XL	25.75 MHz	LVCMOS	3.3V
XLH535013.330000I	Renesas晶振	XTAL OSC XO 13.3300MHZ LVCMOS	XL	13.33 MHz	LVCMOS	3.3V
XLH338040.953873X	Renesas晶振	XTAL OSC XO 40.953873MHZ LVCMOS	XL	40.953873 MHz	LVCMOS	3.3V
XLH300000.000000K	Renesas晶振	XTAL OSC XO HCMOS SMD	XL	-	HCMOS	-
XLH335006.005284K	Renesas Oscillator	XTAL OSC XO 6.005284MHZ HCMOS	XL	6.005284 MHz	HCMOS	3.3V
XLH528031.250000X	Renesas晶振	XTAL OSC XO 31.2500MHZ LVCMOS	XL	31.25 MHz	LVCMOS	2.5V
XLH526031.250000I	Renesas晶振	XTAL OSC XO 31.2500MHZ LVCMOS	XL	31.25 MHz	LVCMOS	2.5V
XLH53V026.000000I	Renesas晶振	XTAL OSC VCXO 26.0000MHZ LVCMOS	XL	26 MHz	LVCMOS	3.3V
XLH535133.333333I	Renesas晶振	XTAL OS XO 133.333333MHZ LVCMOS	XL	133.333333 MHz	LVCMOS	3.3V
XLH535133.330000I	Renesas晶振	XTAL OSC XO 133.3300MHZ LVCMOS	XL	133.33 MHz	LVCMOS	3.3V
XLH736122.906000I	Renesas晶振	OSC 122.906MHZ SMD	*	-	-	-
XLH335074.250000K	Renesas晶振	XTAL OSC XO 74.2500MHZ LVCMOS	XL	74.25 MHz	LVCMOS	3.3V
XLH335037.125000K	Renesas晶振	XTAL OSC XO 37.1250MHZ LVCMOS	XL	37.125 MHz	LVCMOS	3.3V
XLH330002.097152K	Renesas晶振	XTAL OSC XO 2.097152MHZ LVCMOS	XL	2.097152 MHz	LVCMOS	3.3V
XLH335008.000000K	Renesas晶振	XTAL OSC XO 8.0000MHZ LVCMOS SMD	XL	8 MHz	LVCMOS	3.3V
XLH335003.200000K	Renesas晶振	XTAL OSC XO 3.2000MHZ LVCMOS SMD	XL	3.2 MHz	LVCMOS	3.3V
XLH335126.488100K	Renesas晶振	XTAL OSC XO 126.4881MHZ LVCMOS	XL	126.4881 MHz	LVCMOS	3.3V
XLH335100.000000K	Renesas晶振	XTAL OSC XO 100.0000MHZ LVCMOS	XL	100 MHz	LVCMOS	3.3V
XAH335033.333000X	Renesas晶振	CLCC 3.20X2.50X0.90 MM, 2.10MM P	XA	33.333 MHz	HCMOS	3.3V
XAH335033.333333X	Renesas晶振	CLCC 3.20X2.50X0.90 MM, 2.10MM P	XA	33.333333 MHz	HCMOS	3.3V
XAH335060.000000X	Renesas晶振	CLCC 3.20X2.50X0.90 MM, 2.10MM P	XA	60 MHz	HCMOS	3.3V
XLH535036.000000K	Renesas晶振	XTAL OSC XO 36.0000MHZ LVCMOS	XL	36 MHz	LVCMOS	3.3V
XAH335080.000000K	Renesas晶振	OSC XO 80.0000MHZ LVCMOS SMD	XA	80 MHz	LVCMOS	3.3V
XLH3AA100.000000I	Renesas晶振	XTAL OSC XO 100.0000MHZ HCMOS	XL	100 MHz	HCMOS	-
XLH3AA125.000000I	Renesas晶振	XTAL OSC XO 125.0000MHZ HCMOS	XL	125 MHz	HCMOS	-
XLH3AA025.000000I	Renesas晶振	XTAL OSC XO 25.0000MHZ HCMOS SMD	XL	25 MHz	HCMOS	-
XLH536001.843200I	Renesas晶振	XTAL OSC XO 1.8432MHZ HCMOS SMD	XPRESSO  FXO-HC53	1.8432 MHz	HCMOS	3.3V
XLH536033.000000I	Renesas晶振	XTAL OSC XO 33.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	33 MHz	HCMOS	3.3V
XLH536004.000000I	Renesas晶振	XTAL OSC XO 4.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	4 MHz	HCMOS	3.3V
XLH536062.500000I	Renesas晶振	XTAL OSC XO 62.5000MHZ HCMOS SMD	XPRESSO  FXO-HC53	62.5 MHz	HCMOS	3.3V
XLH736060.000000I	Renesas晶振	XTAL OSC XO 60.0000MHZ HCMOS SMD	XPRESSO  FXO-HC73	60 MHz	HCMOS	3.3V
XLH736062.500000I	Renesas晶振	XTAL OSC XO 62.5000MHZ HCMOS SMD	XPRESSO  FXO-HC73	62.5 MHz	HCMOS	3.3V
XLH736066.000000I	Renesas晶振	XTAL OSC XO 66.0000MHZ HCMOS SMD	XPRESSO  FXO-HC73	66 MHz	HCMOS	3.3V
XLH536016.384000I	Renesas晶振	XTAL OSC XO 16.3840MHZ HCMOS SMD	XPRESSO  FXO-HC53	16.384 MHz	HCMOS	3.3V
XLH536066.000000I	Renesas晶振	XTAL OSC XO 66.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	66 MHz	HCMOS	3.3V
XLH736014.318180I	Renesas晶振	XTAL OSC XO 14.31818MHZ HCMOS	XPRESSO  FXO-HC73	14.31818 MHz	HCMOS	3.3V
XLH736016.384000I	Renesas晶振	XTAL OSC XO 16.3840MHZ HCMOS SMD	XPRESSO  FXO-HC73	16.384 MHz	HCMOS	3.3V
XLH736003.686400I	Renesas晶振	XTAL OSC XO 3.6864MHZ HCMOS SMD	XPRESSO  FXO-HC73	3.6864 MHz	HCMOS	3.3V
XLH320180.000000I	Renesas晶振	XTAL OSC XO 180.0000MHZ HCMOS	XPRESSO  FXO-HC32	180 MHz	HCMOS	2.5V
XLH335250.000000I	Renesas晶振	XTAL OSC XO 250.0000MHZ HCMOS	XPRESSO  FXO-HC33	250 MHz	HCMOS	3.3V
XLH526100.000000I	Renesas晶振	XTAL OSC XO 100.0000MHZ HCMOS	XPRESSO  FXO-HC52	100 MHz	HCMOS	2.5V
XLH535225.060000I	Renesas晶振	XTAL OSC XO 225.0600MHZ HCMOS	XPRESSO  FXO-HC53	225.06 MHz	HCMOS	3.3V
XLH535156.250000I	Renesas晶振	XTAL OSC XO 156.2500MHZ HCMOS	XPRESSO  FXO-HC53	156.25 MHz	HCMOS	3.3V
XLH536156.250000X	Renesas晶振	XTAL OSC XO 156.2500MHZ HCMOS	XPRESSO  FXO-HC53	156.25 MHz	HCMOS	3.3V
XLH536135.000000X	Renesas晶振	XTAL OSC XO 135.0000MHZ HCMOS	XPRESSO  FXO-HC53	135 MHz	HCMOS	3.3V
XLH536114.775489I	Renesas晶振	XTAL OSC XO 114.775489MHZ HCMOS	XPRESSO  FXO-HC53	114.775489 MHz	HCMOS	3.3V
XLH536098.304000I	Renesas晶振	XTAL OSC XO 98.3040MHZ HCMOS SMD	XPRESSO  FXO-HC53	98.304 MHz	HCMOS	3.3V
XLH536088.000000I	Renesas晶振	XTAL OSC XO 88.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	88 MHz	HCMOS	3.3V
XLH536066.666000I	Renesas晶振	XTAL OSC XO 66.6660MHZ HCMOS SMD	XPRESSO  FXO-HC53	66.666 MHz	HCMOS	3.3V
XLH536044.545000I	Renesas晶振	XTAL OSC XO 44.5450MHZ HCMOS SMD	XPRESSO  FXO-HC53	44.545 MHz	HCMOS	3.3V
XLH536033.330000I	Renesas晶振	XTAL OSC XO 33.3300MHZ HCMOS SMD	XPRESSO  FXO-HC53	33.33 MHz	HCMOS	3.3V
XLH536013.300000I	Renesas晶振	XTAL OSC XO 13.3000MHZ HCMOS SMD	XPRESSO  FXO-HC53	13.3 MHz	HCMOS	3.3V
XLH536006.000000I	Renesas晶振	XTAL OSC XO 6.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	6 MHz	HCMOS	3.3V
XLH536002.048000I	Renesas晶振	XTAL OSC XO 2.0480MHZ HCMOS SMD	XPRESSO  FXO-HC53	2.048 MHz	HCMOS	3.3V
XLH538100.000000X	Renesas晶振	XTAL OSC XO 100.0000MHZ HCMOS	XPRESSO  FXO-HC53	100 MHz	HCMOS	3.3V
XLH538074.250000X	Renesas晶振	XTAL OSC XO 74.2500MHZ HCMOS SMD	XPRESSO  FXO-HC53	74.25 MHz	HCMOS	3.3V
XLH538050.000000X	Renesas晶振	XTAL OSC XO 50.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	50 MHz	HCMOS	3.3V
XLH538048.000000X	Renesas晶振	XTAL OSC XO 48.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	48 MHz	HCMOS	3.3V
XLH538040.000000X	Renesas晶振	XTAL OSC XO 40.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	40 MHz	HCMOS	3.3V
XLH538033.000000X	Renesas晶振	XTAL OSC XO 33.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	33 MHz	HCMOS	3.3V
XLH538030.720000X	Renesas晶振	XTAL OSC XO 30.7200MHZ HCMOS SMD	XPRESSO  FXO-HC53	30.72 MHz	HCMOS	3.3V
XLH538025.000000X	Renesas晶振	XTAL OSC XO 25.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	25 MHz	HCMOS	3.3V
XLH538020.000000X	Renesas晶振	XTAL OSC XO 20.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	20 MHz	HCMOS	3.3V
XLH538019.200000X	Renesas晶振	XTAL OSC XO 19.2000MHZ HCMOS SMD	XPRESSO  FXO-HC53	19.2 MHz	HCMOS	3.3V
XLH538013.500000X	Renesas晶振	XTAL OSC XO 13.5000MHZ HCMOS SMD	XPRESSO  FXO-HC53	13.5 MHz	HCMOS	3.3V
XLH538013.000000X	Renesas晶振	XTAL OSC XO 13.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	13 MHz	HCMOS	3.3V
XLH538012.288000X	Renesas晶振	XTAL OSC XO 12.2880MHZ HCMOS SMD	XPRESSO  FXO-HC53	12.288 MHz	HCMOS	3.3V
XLH538012.000000X	Renesas晶振	XTAL OSC XO 12.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	12 MHz	HCMOS	3.3V
XLH538010.000000X	Renesas晶振	XTAL OSC XO 10.0000MHZ HCMOS SMD	XPRESSO  FXO-HC53	10 MHz	HCMOS	3.3V

In my ideal digital world, of which I often dream, signal voltage margins are always positive, signal timing margins are always positive, power supply voltages are always within the operating voltage range, and our environment is completely benign.

Unfortunately, none of us live in this ideal world, no matter how much I would like to. The real world is dirty and noisy, and the power distribution in our designs is never perfect. The supply voltage can drop below the operating voltage range resulting in system malfunction or failure, switching transients create noise and reduce signal margins, and impedance discontinuities distort signals reducing signal margins.

Then to make matters worse, we have radiated or conducted noise from internal and external sources to contend with, electrostatic discharge and lightning surges interrupt or destroy systems, and thermal stress, mechanical stress, and component aging all can cause systems to fail. In this short series of blogs, I’d like to look at some of these issues and the measures we can apply to our designs to remove or at least minimize some of these issues.

In this first blog, I’d like to look at some of the typical sources of noise. The table shown here shows the two types of Electromagnetic compatibility or EMC. EMC is defined as the ability of electronic devices to function properly in their intended electromagnetic environment.

EMC comprises two distinct types: EMI or electromagnetic interference, and EMS or electromagnetic susceptibility. EMI is generally known as radiated noise and refers to the disturbances caused by noise, whereas EMS is known as Noise Susceptibility and refers to the damage done to the system due to noise.

In the table below, you can see the different types of EMC and the typical sort of phenomena that they cause. The third column lists some typical products that can be affected by EMI and EMS, resulting in disturbance in operation or damage to the system. This list is by no means complete and is meant only to show some typical examples.

Twenty-five years ago, I was dealing with devices like those in our H8 family, which were implemented on what was then quite advanced process technology, using 1.0μm or even 0.8μm CMOS technology. Today’s devices use significantly more advanced process technology, the latest devices in our RA microcontroller family being implemented on 40 nm technology, with line widths 25 times smaller than the H8 I used to use.

As the transistor size in the latest devices becomes smaller and, probably, more importantly, the transistor switching frequency becomes faster, noise becomes an increasing factor in terms of causing a device to malfunction.

In the diagram above, you can see a simplified comparison between a device using older technology, showing transistor operation with a channel length of 1μm, with the device typically operating from what was then a fast 8 MHz Clock, with a slow transistor switching speed and the latest devices operating at up to 200 MHz or beyond, with a transistor channel length is 40 nm.

In this case, you can see that the switching time is much faster, and for the latest devices, the signal we are trying to deal with can be faster than the noise signal. Therefore, noise has become a larger concern as we move toward smaller process geometry. Renesas has taken many steps on our devices, designing them with features to help operate in such an environment, with carefully designed power supply circuits and optimized I/O buffers and specialist protection circuitry, but it’s still very important to minimize any effects in our designs as much as possible, as at the end, if noise enters the device, it’s much harder to remove.