Raltron振蕩器設(shè)計(jì)優(yōu)化

Oscillator Design Optimization Negative Resistance and Oscillator Circuit Margin
振蕩器設(shè)計(jì)最佳化負(fù)阻和振蕩器電路裕度

Negative Resistance and Oscillator Circuit Margin
負(fù)電阻和振蕩器電路裕量

CIRCUIT MODIFICATION FOR DETERMINATION OF NEGATIVE RESISTANCE “NegR”
用于確定負(fù)電阻“NegR”的電路修改

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.
負(fù)電阻/電路裕度是在良好的頻率匹配(最少的測(cè)量頻率)的平衡下實(shí)現(xiàn)的從在測(cè)試系統(tǒng)上精確測(cè)量然后在電路中測(cè)量的石英晶振的偏移)。電路中的負(fù)載電容值(C1和C2) 直接影響負(fù)電阻的大小和頻率，因此這與的CL(容性負(fù)載)相平衡最佳性能的晶體。

Negative Resistance and Circuit Margin Calculation
負(fù)電阻和電路裕量計(jì)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)
為了開(kāi)始計(jì)算，需要一個(gè)已知的晶體；如果貼片晶振的ESR未知，則C0和CL的值為了確定ESR和R1(RR ),必須知道晶體單元的頻率共振時(shí)的電阻。(公式A)

(1) Determine ESR of crystal unit確定晶體單元的ESR：

R1 = RR = Rs of crystal unit晶體單位的Rs

C0 = shunt capacitance of crystal unit晶體單元的并聯(lián)電容

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.
為了確定負(fù)電阻，可變電阻器(10至20轉(zhuǎn)電位計(jì)，以便更好地調(diào)整精度)被串聯(lián)添加到石英晶體單元。500ω電阻是一個(gè)不錯(cuò)的起始值。但是對(duì)于MHz可以達(dá)到10kω 晶體或1Mω(kHz晶體使用)。

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.
增加可變電阻器的電阻，直到振蕩停止，慢慢將其轉(zhuǎn)回，直到振蕩再次開(kāi)始。到此為止。

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

取出可變電阻器“RTEST ”,用電阻計(jì)測(cè)量調(diào)整后的電阻。

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)

將“RTEST”的值加入等式，確定電路的負(fù)電阻，然后計(jì)算電路裕量(厘米)。(公式B和C)

(2) Calculate Negative Resistance計(jì)算負(fù)電阻

(3) Determine Circuit Margin確定電路余量

(4) RESULT發(fā)生

RTEST = Measured value of variable resistor可變電阻器的測(cè)量值

ESRAVG = Average ESR of typical crystal lot典型晶體批次的平均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

對(duì)于優(yōu)化設(shè)計(jì)的電路,“負(fù)電阻”將優(yōu)于100ω；而電路裕度將是大于10。5到10之間的電路裕度是可以接受的。低于5的電路裕量可能有“啟動(dòng)” 制造和現(xiàn)場(chǎng)可能會(huì)出現(xiàn)問(wèn)題和故障

Crystal Spec Parameters晶體規(guī)格參數(shù)

Recommended Steps to Increase Negative Resistance and Improve Circuit Margin
增加負(fù)電阻的建議步驟提高電路裕度

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:
如果負(fù)電阻過(guò)低和/或晶振ESR過(guò)高，則小于5.0的電路裕量可能過(guò)低。要增加負(fù)電阻/電路裕量:

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

如果可以選擇，降低Rx(限流電阻)的值以增加晶振驅(qū)動(dòng)

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

降低C1和C2的值以增加負(fù)電阻

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

C1和C2電容值的降低將增加車(chē)載頻率

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

for a good frequency match.

使用電鍍到較低CL(容性負(fù)載)的晶體將需要較小的C1和C2值為了良好的頻率匹配。

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

使用ESR較低的晶體。當(dāng)劃分為NegR時(shí)，較低的ESR將產(chǎn)生較高的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.

在可能的情況下，使用帶有ALC(自動(dòng)水平控制)的不同IC來(lái)調(diào)節(jié)驅(qū)動(dòng) 根據(jù)需要調(diào)整水平，以確保有足夠的驅(qū)動(dòng)力和負(fù)阻力晶體信號(hào)振幅水平。

元器件詳情	頻率	頻率穩(wěn)定性	電源電壓	包裝
CO4310-24.576-EXT-TR	24.576MHz	±100ppm	3.3V	卷盤(pán)
Raltron進(jìn)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	卷盤(pán)
Raltron
CO43 系列 3.3 V ±100 ppm -40 至 +85°C 7 x 5 mm 表面貼裝時(shí)鐘振蕩器
CO4310-25.000-TR	25MHz	±100ppm	3.3V	卷盤(pán)
Raltron
CO43 系列 25 MHz ± 100 ppm 7 x 5 mm 3.3 V 表面貼裝時(shí)鐘振蕩器
CO4310-29.4912-TR	29.4912MHz	±100ppm	3.3V	卷盤(pán)
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	卷盤(pán)
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	卷盤(pán)
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	卷盤(pán)
Raltron
CO43 系列 48 MHz 3.3 V ±100 ppm 表面貼裝時(shí)鐘振蕩器
CO4310-5.000-EXT-TR	5MHz	±100ppm	3.3V	卷盤(pán)
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	卷盤(pán)
Raltron
CO43 系列 7 x 5 mm 5 MHz ±50 ppm -10 至 70°C 表面貼裝時(shí)鐘振蕩器
CO4310-50.000-EXT-T-TR	50MHz	±100ppm	3.3V	卷盤(pán)
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	卷盤(pán)
Raltron
CO43 系列 50 MHz 7 x 5 mm 3.3 V ±50 ppm 表面貼裝時(shí)鐘振蕩器
CO4310-6.000-T-TR	6MHz	±100ppm	3.3V	剪切卷帶
Raltron
CO43 系列 6 MHz 7 x 5 mm 3.3 V ±100 ppm 表面貼裝時(shí)鐘振蕩器
CO4310-8.000-EXT-T-TR	8MHz	±100ppm	3.3V	卷盤(pán)
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	袋裝
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	卷盤(pán)
Raltron石英晶體振蕩器
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	卷盤(pán)
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	卷盤(pán)
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	散裝
Raltron
CO46 系列 100 MHz 7 x 5 mm 3.3 V ±50 ppm 表面貼裝時(shí)鐘振蕩器
CO4605-125.000-EXT-TR	125MHz	±50ppm	3.3V	卷盤(pán)
Raltron
CO46 系列 125 MHz 7 x 5 mm 3.3 V ±50 ppm 表面貼裝時(shí)鐘振蕩器
CO4605-60.000M-EXT-TR	60MHz	±50ppm	3.3V	卷盤(pán)
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	卷盤(pán)
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	卷盤(pán)
Raltron
CO46 系列 66 MHz ±50 ppm 3.3 V -40 至 +85°C 表面貼裝時(shí)鐘振蕩器
CO4605-66.000-T-TR	66MHz	±50ppm	3.3V	卷盤(pán)
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	卷盤(pán)
Raltron
CO46 系列 80 MHz ± 50 ppm 7 x 5 mm 3.3 V 表面貼裝時(shí)鐘振蕩器
CO4605S-66.600-EXT-T-TR	66.6MHz	±50ppm	3.3V	卷盤(pán)
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	剪切卷帶
Raltron
CO46 系列 133.33 MHz 7 x 5 mm 3.3 V ±100 ppm 表面貼裝時(shí)鐘振蕩器

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