Raltron振荡器设计优化

Oscillator Design Optimization Negative Resistance and Oscillator Circuit Margin
振荡器设计最佳化负阻和振荡器电路裕度

Negative Resistance and Oscillator Circuit Margin
负电阻和振荡器电路裕量

CIRCUIT MODIFICATION FOR DETERMINATION OF NEGATIVE RESISTANCE “NegR”
用于确定负电阻“NegR”的电路修改

Negative Resistance/Circuit Margin is performed with a balance of good frequency match (least amount of measured frequency shift from a crystals measured accurately on a test system and then in circuit). The load capacitor values in circuit (C1 and C2) directly effect the amount of Negative Resistance and the Frequency, so this is balanced with the CL (capacitive load) of the crystal for optimum performance.
负电阻/电路裕度是在良好的频率匹配(最少的测量频率)的平衡下实现的从在测试系统上精确测量然后在电路中测量的石英晶振的偏移)。电路中的负载电容值(C1和C2) 直接影响负电阻的大小和频率，因此这与的CL(容性负载)相平衡最佳性能的晶体。

Negative Resistance and Circuit Margin Calculation
负电阻和电路裕量计算

To start the calculations a good known crystal is needed; if the ESR of the crystal is not known, the values for C0 and CL of the crystal unit must be known in order to determine ESR along with the R1(RR) which is the measured Resistance at Frequency Resonance. (Formula A)
为了开始计算，需要一个已知的晶体；如果贴片晶振的ESR未知，则C0和CL的值为了确定ESR和R1(RR ),必须知道晶体单元的频率共振时的电阻。(公式A)

(1) Determine ESR of crystal unit确定晶体单元的ESR：

R1 = RR = Rs of crystal unit晶体单位的Rs

C0 = shunt capacitance of crystal unit晶体单元的并联电容

In order to determine the negative resistance a variable resistor(10 to 20 turn potentiometers for better adjustment accuracy) is added in series to the crystal unit. A 500 Ω resistor is a good value to start with. but could go up to 10 k? for MHz crystals or 1 M? for kHz crystals using.
为了确定负电阻，可变电阻器(10至20转电位计，以便更好地调整精度)被串联添加到石英晶体单元。500ω电阻是一个不错的起始值。但是对于MHz可以达到10kω 晶体或1Mω(kHz晶体使用)。

Increase the resistance of the variable resistor until oscillation stops, slowly turn it back until the oscillation just starts up again. Stop at this point.
增加可变电阻器的电阻，直到振荡停止，慢慢将其转回，直到振荡再次开始。到此为止。

Take the variable resistor 'RTEST' out and measure the adjusted resistance using a resistance meter.

取出可变电阻器“RTEST ”,用电阻计测量调整后的电阻。

Add the value of 'RTEST' into the equation to determine Negative Resistance of the circuit and then calculate the Circuit Margin (CM). (Formulas B and C)

将“RTEST”的值加入等式，确定电路的负电阻，然后计算电路裕量(厘米)。(公式B和C)

(2) Calculate Negative Resistance计算负电阻

(3) Determine Circuit Margin确定电路余量

(4) RESULT发生

RTEST = Measured value of variable resistor可变电阻器的测量值

ESRAVG = Average ESR of typical crystal lot典型晶体批次的平均ESR

For an optimally designed circuit the 'Negative Resistance' would be better than 100 ?; while the Circuit Margin would be greater than 10. A Circuit Margin between 5 to 10 would be acceptable. A Circuit Margin below 5 could have 'start-up' problems and failuresin manufacturing and in the field may occur

对于优化设计的电路,“负电阻”将优于100ω；而电路裕度将是大于10。5到10之间的电路裕度是可以接受的。低于5的电路裕量可能有“启动” 制造和现场可能会出现问题和故障

Crystal Spec Parameters晶体规格参数

Recommended Steps to Increase Negative Resistance and Improve Circuit Margin
增加负电阻的建议步骤提高电路裕度

If the Negative Resistance is too low and or the crystal ESR is too high, the Circuit Margin can be too low if less than 5.0. To increase the Negative Resistance/Circuit Margin:
如果负电阻过低和/或晶振ESR过高，则小于5.0的电路裕量可能过低。要增加负电阻/电路裕量:

1. Lower the value of Rx (current limiting resistor) to increase the crystal drive if this is an option.

如果可以选择，降低Rx(限流电阻)的值以增加晶振驱动

2. Lower the values of C1 and C2 to increase Negative Resistance.

降低C1和C2的值以增加负电阻

a. A decrease in C1 and C2 capacitive value will increase the on-board frequency.

C1和C2电容值的降低将增加车载频率

b. Using a crystal plated to a lower CL (Capacitive Load) will need smaller values of C1 and C2

for a good frequency match.

使用电镀到较低CL(容性负载)的晶体将需要较小的C1和C2值为了良好的频率匹配。

3. Use a crystal with a lower ESR. Lower ESR when divided into NegR will give a higher CM.

使用ESR较低的晶体。当划分为NegR时，较低的ESR将产生较高的CM。

4. Where possible use a different IC with ALC (Automatic Level Control) which adjusts the drive

level as needed to ensure there is enough drive and negative resistance to have a consistent

crystal signal amplitude level.

在可能的情况下，使用带有ALC(自动水平控制)的不同IC来调节驱动根据需要调整水平，以确保有足够的驱动力和负阻力晶体信号振幅水平。

元器件详情	频率	频率稳定性	电源电压	包装
CO4310-24.576-EXT-TR	24.576MHz	±100ppm	3.3V	卷盘
Raltron进口晶振
CO43 Series 24.576 MHz 7 x 5 mm 3.3 V ±100 ppm Surface Mount Clock Oscillator
CO4310-25.000-EXT-TR	25MHz	±100ppm	3.3V	卷盘
Raltron
CO43 系列 3.3 V ±100 ppm -40 至 +85°C 7 x 5 mm 表面贴装时钟振荡器
CO4310-25.000-TR	25MHz	±100ppm	3.3V	卷盘
Raltron
CO43 系列 25 MHz ± 100 ppm 7 x 5 mm 3.3 V 表面贴装时钟振荡器
CO4310-29.4912-TR	29.4912MHz	±100ppm	3.3V	卷盘
Raltron
CO4 Series 29.4912 MHz 3.3 V ±100 ppm -20°C TO +70°C SMT CMOS Clock Oscillator
CO4310-32.000-EXT-TR	32MHz	±100ppm	3.3V	卷盘
Raltron
CO4 Series 32 MHz 3.3 V ±100 ppm -40°C TO +85°C SMT CMOS Clock Oscillator
CO4310-40.000MHZ	40MHz	±100ppm	3.3V	卷盘
Raltron
CO4 Series 40 MHz 3.3 V ±100 ppm -20°C TO +70°C SMT CMOS Clock Oscillator
CO4310-48.000-T-TR	48MHz	±100ppm	3.3V	卷盘
Raltron
CO43 系列 48 MHz 3.3 V ±100 ppm 表面贴装时钟振荡器
CO4310-5.000-EXT-TR	5MHz	±100ppm	3.3V	卷盘
Raltron
CO4 Series 5 MHz 3.3 V ±100 ppm -40°C TO +85°C SMT CMOS Clock Oscillator
CO4310-5.000-T-TR	5MHz	±100ppm	3.3V	卷盘
Raltron
CO43 系列 7 x 5 mm 5 MHz ±50 ppm -10 至 70°C 表面贴装时钟振荡器
CO4310-50.000-EXT-T-TR	50MHz	±100ppm	3.3V	卷盘
Raltron
CO4 Series 50 MHz 3.3 V ±100 ppm -40°C TO +85°C SMT CMOS Clock Oscillator
CO4310-50.000-T-TR	50MHz	±100ppm	3.3V	卷盘
Raltron
CO43 系列 50 MHz 7 x 5 mm 3.3 V ±50 ppm 表面贴装时钟振荡器
CO4310-6.000-T-TR	6MHz	±100ppm	3.3V	剪切卷带
Raltron
CO43 系列 6 MHz 7 x 5 mm 3.3 V ±100 ppm 表面贴装时钟振荡器
CO4310-8.000-EXT-T-TR	8MHz	±100ppm	3.3V	卷盘
Raltron
CO4 Series 8 MHz 3.3 V ±100 ppm -40°C TO +85°C SMT CMOS Clock Oscillator
CO4310S-16.384-TR	16.384MHz	±100ppm	3V to 3.6V	袋装
Raltron
CO43 Series 16.384 MHz 7 x 5 mm 3.6 V ±100 ppm SMT CMOS/TTL Clock Oscillator
CO4310S-50.000-EXT-TR	50MHz	±100ppm	3.3V	卷盘
Raltron石英晶体振荡器
CO4 Series 50 MHz 3.3 V ±100 ppm -40°C TO +85°C SMT CMOS Clock Oscillator
CO46025S-100.000-TR	100MHz	±25ppm	3.3V	卷盘
Raltron
CO46 Series 100 MHz 7 x 5 mm 3.3 V ±25 ppm Surface Mount Clock Oscillator
CO46025S-66.670-EXT-TR	66.67MHz	±25ppm	3.3V	卷盘
Raltron
CO4 Series 66.67 MHz 3.3 V ±25 ppm -40°C TO +85°C SMT CMOS Clock Oscillator
CO4605-100.000-EXT-T-TR	100MHz	±50ppm	3.3V	散装
Raltron
CO46 系列 100 MHz 7 x 5 mm 3.3 V ±50 ppm 表面贴装时钟振荡器
CO4605-125.000-EXT-TR	125MHz	±50ppm	3.3V	卷盘
Raltron
CO46 系列 125 MHz 7 x 5 mm 3.3 V ±50 ppm 表面贴装时钟振荡器
CO4605-60.000M-EXT-TR	60MHz	±50ppm	3.3V	卷盘
Raltron
CO46 Series 60 MHz 7 x 5 mm 3.3 V ±50 ppm Surface Mount Clock Oscillator
CO4605-62.500-T-TR	62.5MHz	±50ppm	3.3V	卷盘
Raltron
CO4 Series 62.5 MHz 3.3 V ±50 ppm -20°C TO +70°C SMT CMOS Clock Oscillator
CO4605-66.000-EXT-T-TR	66MHz	±50ppm	3.3V	卷盘
Raltron
CO46 系列 66 MHz ±50 ppm 3.3 V -40 至 +85°C 表面贴装时钟振荡器
CO4605-66.000-T-TR	66MHz	±50ppm	3.3V	卷盘
Raltron
CO4 Series 66 MHz 3.3 V ±50 ppm -20°C TO +70°C SMT CMOS Clock Oscillator
CO4605-80.000-EXT-TR	80MHz	±50ppm	3.3V	卷盘
Raltron
CO46 系列 80 MHz ± 50 ppm 7 x 5 mm 3.3 V 表面贴装时钟振荡器
CO4605S-66.600-EXT-T-TR	66.6MHz	±50ppm	3.3V	卷盘
Raltron
CO4 Series 66.6 MHz 3.3 V ±50 ppm -40°C TO +85°C SMT CMOS Clock Oscillator
CO4610-133.33-T-TR	133MHz	±100ppm	3.3V	剪切卷带
Raltron
CO46 系列 133.33 MHz 7 x 5 mm 3.3 V ±100 ppm 表面贴装时钟振荡器

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