A TechNote for Crystal
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Figure 3
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AT cut
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-100 Frequency Stability -200
-250
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BT cut
-400
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-500 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature in degrees C
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Figure 2 Mode of vibrations Thickness-share Crystal cuts AT Calculation formula for frequency 1670 / t Acceptable KDS products frequency range at KDS 1.8 ~ 200MHz HC-49/U, UM-1/5/4 rd th (Fund., 3 , 5 ) AT-49, SMD-49 AT-38, DMX-38 DSX SERIES MCFs OSCLLATORs BT Length-width flexure +2°X 2560 / t 700 x w / l2 40 ~ 60MHz (Fund.) 15 ~ 150kHz DSX840GAB DSX630G-B DT-38/381/26/261 DMX-38/26/26S SM-26F, SM-14J DST SERIES
AMERICA
DAISHINKU (AMERICA) CORP.
Technical notes for crystal units and crystal oscillator circuits n n n n Crystal cuts Modes of vibration Frequency vs. temperature stability in crystal cuts AT cut crystal units
n Oscillator circuits for crystal units
n Evaluation method for oscillator circuit
n A test report for crystal oscillator circuit
- An oscillator circuit evaluation for AT cut crystal units in MHz - An oscillator circuit evaluation for tuning fork crystal units in kHz - An oscillator circuit evaluation for AT cut crystal units in MHz - An oscillator circuit evaluation for tuning fork crystal units in kHz
n Modes of vibration in crystal
The crystal cuts as shown in Figure 1 vibrate in various modes; the most important modes are the flexure and thickness-shear. The mode of vibration determines the maximum frequency, frequency vs. temperature stability, and resistance of crystal units. The various modes of vibration are shown in Figure 2, and the various frequencies vs. temperature stability are shown in Figure 3.
n A test report for start up time of crystal oscillator circuit n Oscillator circuit evaluation at KDS (Example 1) n Oscillator circuit evaluation at KDS (Example 2) n Conclusion
80 60 Frequency Stability in PPM 40 20 0 -20 -40 -60 -80 -100 -50 -40 -30 -20 -10 0 100 80 60 Frequency Stability in PPM 40 20 0 -20 -40 -60 -80 -100 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature in degrees C
- Oscillator circuit examples for fundamental - Oscillator circuit examples for 3rd Overtone - Calculation formula of the load capacitance of oscillator circuit - Theory of oscillator circuit for crystal unit - To obtain the negative resistance of oscillator circuit - Confirmation method for abnormal oscillation - To obtain the drive level of oscillator circuit - Measurement equipment
Of the various crystal cuts, the "AT" cut has become the most popular that is available at higher frequencies than the others, it shows excellent frequency vs. temperature stability due to the cubic curves. The other cuts show the parabolic curves in frequency vs. temperature stability.
- Frequency vs. temperature stability - Inside structure examples - Fundamental and Overtone - Tuning fork crystal units - AT cut crystal units
n Drive level dependency in crystal units n n n n Activity dips in AT cut crystal units Crystal unit equivalent circuit Load capacitance Pullability and Pulling Sensitivity
n Crystal cuts
Crystal unit works for controlling the oscillation frequency of oscillator circuit by conversion of mechanical vibrations to electrical current at a specific frequency. This is called the "Piezoelectric" effect. In some materials, which the piezoelectric effect is found, crystal is suited for the manufacture of frequency control devices. Various crystal cuts for crystal units have been found as shown in Figure 1 over the years. Figure 1 shows the location of crystal cuts developed in synthetic quartz stone. Figure 1
4
n AT cut crystal units
Frequency vs. temperature stability
The frequencies vs. temperature curves of the "AT" cut crystal unit are shown in Figure 4. Figure 4 100
Inside structures (For example)
Figure 5
6
Fundamental and Overtone
AT cut crystal unit resonates at odd integer multiples of the fundamental frequency. (1,3,5, etc.) For example, with a fundamental crystal of 20MHz, the crystal unit has resonance frequencies at 20, 60, and 100MHz. As the frequency of crystal unit is higher, the thickness of internal crystal blank is thinner. To calculate the thickness of crystal blank, use the calculation formula in Figure 2. For example, 1. Fundamental crystal unit: 20MHz, the thickness of crystal blank is: 1670/t=20000(kHz), t=0.0835mm 2. Fundamental crystal unit: 30MHz, the thickness of crystal blank is: 1670/t=30000(kHz), t=0.0557mm Also, the AT-49 as an example, the fundamental crystal unit is acceptable up to 35MHz and the 3rd overtone crystal unit is used for higher frequencies than 35MHz, because the crystal blank becomes too thin for mechanical polishing. A resonance characteristic for a crystal unit of 20MHz in fundamental is shown in Figure 6. Figure 6
100
50
AT cut
0
-50
-100 Frequency Stability -200
-250
-300
-350
BT cut
-400
-450
-500 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature in degrees C
2
Figure 2 Mode of vibrations Thickness-share Crystal cuts AT Calculation formula for frequency 1670 / t Acceptable KDS products frequency range at KDS 1.8 ~ 200MHz HC-49/U, UM-1/5/4 rd th (Fund., 3 , 5 ) AT-49, SMD-49 AT-38, DMX-38 DSX SERIES MCFs OSCLLATORs BT Length-width flexure +2°X 2560 / t 700 x w / l2 40 ~ 60MHz (Fund.) 15 ~ 150kHz DSX840GAB DSX630G-B DT-38/381/26/261 DMX-38/26/26S SM-26F, SM-14J DST SERIES
AMERICA
DAISHINKU (AMERICA) CORP.
Technical notes for crystal units and crystal oscillator circuits n n n n Crystal cuts Modes of vibration Frequency vs. temperature stability in crystal cuts AT cut crystal units
n Oscillator circuits for crystal units
n Evaluation method for oscillator circuit
n A test report for crystal oscillator circuit
- An oscillator circuit evaluation for AT cut crystal units in MHz - An oscillator circuit evaluation for tuning fork crystal units in kHz - An oscillator circuit evaluation for AT cut crystal units in MHz - An oscillator circuit evaluation for tuning fork crystal units in kHz
n Modes of vibration in crystal
The crystal cuts as shown in Figure 1 vibrate in various modes; the most important modes are the flexure and thickness-shear. The mode of vibration determines the maximum frequency, frequency vs. temperature stability, and resistance of crystal units. The various modes of vibration are shown in Figure 2, and the various frequencies vs. temperature stability are shown in Figure 3.
n A test report for start up time of crystal oscillator circuit n Oscillator circuit evaluation at KDS (Example 1) n Oscillator circuit evaluation at KDS (Example 2) n Conclusion
80 60 Frequency Stability in PPM 40 20 0 -20 -40 -60 -80 -100 -50 -40 -30 -20 -10 0 100 80 60 Frequency Stability in PPM 40 20 0 -20 -40 -60 -80 -100 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 Temperature in degrees C
- Oscillator circuit examples for fundamental - Oscillator circuit examples for 3rd Overtone - Calculation formula of the load capacitance of oscillator circuit - Theory of oscillator circuit for crystal unit - To obtain the negative resistance of oscillator circuit - Confirmation method for abnormal oscillation - To obtain the drive level of oscillator circuit - Measurement equipment
Of the various crystal cuts, the "AT" cut has become the most popular that is available at higher frequencies than the others, it shows excellent frequency vs. temperature stability due to the cubic curves. The other cuts show the parabolic curves in frequency vs. temperature stability.
- Frequency vs. temperature stability - Inside structure examples - Fundamental and Overtone - Tuning fork crystal units - AT cut crystal units
n Drive level dependency in crystal units n n n n Activity dips in AT cut crystal units Crystal unit equivalent circuit Load capacitance Pullability and Pulling Sensitivity
n Crystal cuts
Crystal unit works for controlling the oscillation frequency of oscillator circuit by conversion of mechanical vibrations to electrical current at a specific frequency. This is called the "Piezoelectric" effect. In some materials, which the piezoelectric effect is found, crystal is suited for the manufacture of frequency control devices. Various crystal cuts for crystal units have been found as shown in Figure 1 over the years. Figure 1 shows the location of crystal cuts developed in synthetic quartz stone. Figure 1
4
n AT cut crystal units
Frequency vs. temperature stability
The frequencies vs. temperature curves of the "AT" cut crystal unit are shown in Figure 4. Figure 4 100
Inside structures (For example)
Figure 5
6
Fundamental and Overtone
AT cut crystal unit resonates at odd integer multiples of the fundamental frequency. (1,3,5, etc.) For example, with a fundamental crystal of 20MHz, the crystal unit has resonance frequencies at 20, 60, and 100MHz. As the frequency of crystal unit is higher, the thickness of internal crystal blank is thinner. To calculate the thickness of crystal blank, use the calculation formula in Figure 2. For example, 1. Fundamental crystal unit: 20MHz, the thickness of crystal blank is: 1670/t=20000(kHz), t=0.0835mm 2. Fundamental crystal unit: 30MHz, the thickness of crystal blank is: 1670/t=30000(kHz), t=0.0557mm Also, the AT-49 as an example, the fundamental crystal unit is acceptable up to 35MHz and the 3rd overtone crystal unit is used for higher frequencies than 35MHz, because the crystal blank becomes too thin for mechanical polishing. A resonance characteristic for a crystal unit of 20MHz in fundamental is shown in Figure 6. Figure 6
