Tech Talk

These Ecliptek series oscillators are VCXO's. The term VCXO refers to a voltage controlled crystal oscillator. These product series are simply a crystal oscillator where the output frequency is controlled by an external control voltage applied to the input of the oscillator.

A VCXO is a crystal controlled oscillator where the output frequency of the oscillator is being controlled by the crystal and an external control voltage. VCXO's are designed with a varactor replacing a fixed capacitor internal to the oscillator. A varactor diode is a semiconductor device that behaves as a variable capacitor when a voltage is applied to it. Thus, when a change in the control voltage is applied to the control pad of the oscillator, it causes a change in the capacitance of the varactor diode. This results in a change in the overall load capacitance seen by the crystal internal to the oscillator. These changes in the circuit load capacitance cause changes in the oscillator output frequency due to crystal loading. As a result, variations in output frequency are achieved by variations in the external control voltage. This phenomenon is often called frequency modulation.

These product series oscillator can be used in the following circuit applications:

• Clock Recovery
• Phase-Locked Loops (PLL's)
• Frequency Modulation/Demodulation
• Reference Signal Tracking
• Synthesizers
• Digital Switching

These series of oscillators are commonly used in the following customer products:

• xDSL Customer Premise Equipment (CPE)
• Hybrid Fiber Coax Equipment (HFC)
• Cable Modems
• SONET/ATM/SDH Equipment
• MPEG Audio/Video Equipment
• 1G, 2G, 4G, 10G Fiber Channel

These product series offer:

• Improved frequency stability through the use of a fundamental mode BAW (bulk acoustic wave) crystal
• Output frequencies up to 77.760MHz
• Supply Voltages of 3.3V_DC and 5.0V_DC
• ±50ppm, ±80ppm, and ±100ppm Minimum Absolute Pull Ranges (APR)
• Tight Duty Cycle (45%/55%)
• 10% typical and 20% maximum Linearity
• Excellent rms phase jitter performance
• Low Phase Noise
• Commercial and industrial temperature ranges
• Tri-state function high impedance output
• Low profile six pad ceramic SMD package
• RoHS Compliant (Pb-free) with high temperature 260°C reflow capability

These series oscillators (EV31C3, EV32C3, EV31C6, and EV32C6) are offered in the industry standard six-pad leadless ceramic SMD package.

The EV31C3 and EV31C6 series are 5.0Vdc versions. The EV32C3 and EV32C6 series are offered at 3.3Vdc for lower voltage applications.

The input current specification is listed as a maximum on the respective datasheet (EV31C3, EV32C3, EV31C6, and EV32C6). These current ratings are for oscillators with the specified output load connected.

These series feature standard frequencies ranging from 1.544MHz to 77.760MHz. Certain frequencies can be provided above this frequency range on a case-by-case basis. Please contact us with your custom requirements.

These product series consist of a single ASIC and fundamental mode BAW quartz crystal packaged inside a hermetically sealed ceramic leadless SMD package. The leadless SMD package has six gold plated contact I/O pads. The package has a seam sealed metal cover that is case grounded for improved EMI performance.

There are two common methods customers and suppliers use for specifying VCXO's. The first method is to specify the performance of the device inclusive of all operating conditions. This is called the APR Method. The second method is to specify device performance under specific operating conditions and to specify separate operating parameters such as frequency deviation, frequency tolerance, frequency stability over operating temperature range, supply voltage, output load, and aging. This is called the Separate Method. These oscillator series oscillators use the APR Method for specifying the VCXO. This method utilizes the absolute pull range (APR) definition. The advantage of the APR Method is that a customer can simply specify one parameter, APR, rather than specifying many individual parameters such as frequency deviation, temperature stability over operating temperature range, output load, supply voltage, and aging. See Table 1 below for a comparison of the APR Method and the Separate Method.

Table 1: APR vs. Separate Method

VCXO Output Parameter	APR Method	Separate Method
Calibration Tolerance		±10ppm MAX
Stability over OTR		±40ppm MAX
Stability vs. Supply Voltage		±5ppm MAX
Stability vs. Output Load		±5ppm MAX
Aging over 10 years		±10ppm MAX
Pullability/Frequency Deviation		±150ppm MIN
Absolute Pull Range (APR)	±80ppm Minimum
Operating Temperature Range (OTR)	-40°C to +85°C	-40°C to +85°C

As shown in Table 1 above, the APR Method of ±80ppm minimum in the second column is equivalent to the Separate Method of ±150ppm pullability in the third column.

APR stands for absolute pull range. APR is defined as the minimum guaranteed frequency deviation (specified in ±ppm) from the nominal frequency (F₀) over all operating parameters. These operating parameters include: frequency tolerance, frequency stability over operating temperature range, supply voltage, output load, and aging. For example, a 35.328MHz VCXO used in a PLL clock recovery circuit that has a ±50ppm minimum APR specification will track or capture a ±50ppm maximum 35.328MHz source oscillator under all operating conditions.

For frequencies from 1.544MHz to 36.000MHz , these product series offers the following APR options: ±50ppm, ±80ppm, and ±100ppm minimum. For frequencies greater than 36.00MHz to 51.840MHz, these product series offers both the ±50ppm APR and ±80ppm APR option. For frequencies greater than 51.840MHz, these product series only offer the ±50ppm APR option.

The control voltage range (V_CR) is the minimum and maximum voltage that can be applied to the voltage control pad (pad 1) of the oscillator. The control voltage range is 0.0V_DC to V_DD (Supply Voltage) for these series oscillators. The control coltage (V_C) is the voltage applied to the voltage control pad (pad 1) of the oscillator for the measurement of the APR test conditions. The control voltage is dependent upon the specific product series. For VCXO's with a power supply voltage of 5.0V_DC (EV31C3 and EV31C6 series), the control voltage is 0.5V_DC to 4.5V_DC. For VCXO's with a power supply voltage of 3.3V_DC (EV32C3 and EV32C6 series), the control voltage is 0.3V_DC to 3.0V_DC.

The pullability or frequency deviation of a VCXO refers to the amount of frequency change (in ppm) with respect to a change in the control voltage (V_C). These parameters are specified when using the Separate Method mentioned above. These product series do not specify VCXO pullability or frequency deviation. These series specifies the APR Method. As a matter of interest, the total pullability or frequency deviation of these Ecliptek product series is typically 200ppm to 400ppm over the control voltage test conditions, depending upon the APR option specified by the customer. If a customer would like to specify a VCXO using the Separate Method, please contact an Ecliptek sales representative.

Ecliptek offers a commercial temperature range of 0°C to +70°C and an industrial temperature range of -40°C to +85°C.

These product series do not specify a maximum frequency tolerance/stability option. The frequency tolerance/stability for these series is typically ±50ppm over the operating temperature range of -40°C to +85°C or 0°C to +70°C.

Aging is the systematic change in frequency with time due to internal changes in the crystal and/or oscillator. Aging is often expressed as a maximum value in parts per million per year [ppm/year]. The rate of aging is logarithmic in nature. The following factors effect crystal aging: adsorption and desorption of contamination on the surfaces of the quartz, stress relief of the mounting and bonding structures, material outgassing, and seal integrity. At a rated operating temperature of 25°C, these series of products typically age at a rate of ±2ppm over the first year, ±1ppm over the following year, logarithmically declining each year there after. The aging parameters can be found on the EV31C3, EV32C3, EV31C3, and EV32C6 series specification sheets. It should be noted that oscillator aging is inclusive of the APR.

Jitter is the measure in the time domain and is specified in picoseconds (pSec) as a maximum RMS value. Phase noise is a measure in the frequency domain and is specified in decibels at various offset points from the carrier (-dBc/Hz). Ecliptek uses a proprietary design, exclusive processing methods, and a unique output driver circuit enabling these oscillator series to have exceptionally low jitter and phase noise. The RMS phase jitter and phase noise parameters can be found on the EV31C3, EV32C3, EV31C6, and EV32C6 series specifications sheets.

Yes, these series offers tri-state output capability. For the EV31C3 and EV32C3 series, pad five (5) is the tri-state input pad. For the EV31C3 and EV32C6 series, pad two (2) is the tri-state input pad. The output is three-stated (tri-state condition) when the voltage at the control pad is set to a logic low state. In this condition, the oscillator continues to operate, but the output pad is now in a high impedance state. If the voltage at the control pad is set to no connect or a logic high state, the output is enabled (clocking). Note: The oscillator has an internal pull up resistor on the control pad.

Tight duty cycle, specified as a maximum value, is not available for these product series. The duty cycle for these series is typically 45% minimum to 55% maximum. However, the specification limit is 40% minimum, 60% maximum (under all operating conditions).

These oscillators have a high speed CMOS output driver that enables the output signal to swing from ground to V_DD. Ecliptek offers the 5.0V_DC EV31C3 and EV31C6 VCXO series with a 10TTL compatible or 30pF HCMOS output load. The 3.3V_DC EV32C3 and EV32C6 VCXO series offer a 10TTL compatible or 30pF HCMOS output load for output frequencies less than or equal to 12.288MHz and 15pF HCMOS output load for frequencies greater than 12.288MHz. Ecliptek does not currently offer this product in True TTL or ECL logic outputs. If a customer requires a different load from that specified above, please consult the factory with your custom requirements.

Often called slope, the transfer function of a VCXO is the direction the frequency changes with respect to the control voltage. Positive slope means the output frequency is increasing with increasing control voltage. Negative slope means that the output frequency is increasing with decreasing control voltage. The transfer function for these oscillator series is positive.

Often called monotonic linearity, this parameter is the calculation of the frequency error expressed in percentage with reference from the best straight line curve fit drawn on the output frequency versus control voltage graph. The linearity curve is the relationship between output frequency versus control voltage. The linearity specifications can be found on the applicable Ecliptek specification sheets (EV31C3, EV32C3, EV31C6, and EV32C6). In a phase locked loop application the linearity requirements may be very loose. While in a frequency modulation application the linearity requirement may be very stringent.

Often called tuning or video bandwidth, modulation bandwidth (MBW) is the modulation frequency at the input of the VCXO at which the output frequency deviation decreases to -3dB of its DC value. Input Impedance specifies the load of the VCXO control input pad (pad 1). The MBW and Input Impedance parameters can be found on the applicable Ecliptek specification sheet (EV31C3, EV32C3, EV31C6, and EV32C6)

Start-up time for these series is specified at 10mSec maximum. Note: In order to ensure proper start-up, the power supply start-up should have an exponential curve typical of a capacitive charge of a linear voltage ramp. If you have a special voltage start-up profile (i.e. odd ramp steps or shapes), please contact us to discuss possible oscillator performance issues.

It is recommended that the customer use the test fixture specified by Ecliptek. This information is available in 'Other Resources' section on the applicable series specification datasheet(EV31C3, EV32C3, EV31C6, and EV32C6).

If the part number is specified with the TR option, these product series oscillators are delivered to the customer in EIA481A compliant tape and reel packaging. Without the TR option, these products are delivered to the customer in industry standard plastic tubes. See the applicable specification (EV31C3, EV32C3, EV31C6, and EV32C6) for packaging dimensions and suggested solder reflow diagrams. These product series are capable of withstanding industry standard high temperature (260°C, 10 seconds) convection reflow processes.

These product series are RoHS compliant and Pb-free as defined in the Ecliptek Pb-free Roadmap and are capable of withstanding industry standard high temperature convection reflow processes. See the recommended solder reflow methods listed on the applicable specification data sheet.

A RoHS product certification letter can be obtained directly from our website by using our Ecliptek RoHS Certification Letter Generator.

Ecliptek recommends that the customer first determine if the tri-state output feature is required. This will determine if a four pad or six pad (with tri-state feature) board layout is needed. See the applicable specification (EV31C3, EV32C3, EV31C6, and EV32C6) for suggested solder pad layout.

Please see the Ecliptek Competitor Part Number Crosser.

Obtaining a quote on-line is simple. Simply fill in the required information in the part number constructor for the specific series that you would like to order. This part number will define the specifications you desire. After you construct a part number, you can request a quote or check stock by following the prompts on our website. You can go to a part number constructor now by selecting a link below:

EV Series	Package Type	Supply Voltage	Tri-State Option
EV31C3	Ceramic Six Pad	5.0VDC	Pad 5
EV32C3	Ceramic Six Pad	3.3VDC	Pad 5
EV31C6	Ceramic Six Pad	5.0VDC	Pad 2
EV32C6	Ceramic Six Pad	3.3VDC	Pad 2

You can go to the specific series you desire now by selecting a link below. At the bottom of the page under Other Resources, select Download Specification.

EV Series	Package Type	Supply Voltage	Tri-State Option
EV31C3	Ceramic Six Pad	5.0VDC	Pad 5
EV32C3	Ceramic Six Pad	3.3VDC	Pad 5
EV31C6	Ceramic Six Pad	5.0VDC	Pad 2
EV32C6	Ceramic Six Pad	3.3VDC	Pad 2

Simply fill in the required information in the part number constructor for the specific series that you would like to order. This part number will define the specifications you desire. After you construct a part number, you will be prompted with the following: Get a data sheet for this part number (PDF).

The engineering staff at Ecliptek can provide applications engineering support or answer customer technical questions.

Complete the Ecliptek Custom Oscillator Request Form from our website. From this page you will be able to enter custom specifications that are unavailable from the standard part number constructor forms. These parameters will be sent to our Engineering team where they will be evaluated. Upon acceptance, a custom part number will be assigned and an engineering document created to represent your product.

The environmental and mechanical specifications for each product series is listed on the applicable specifications.

Failure in Time (FIT) and Mean Time To Failure (MTTF) reliability data is available from the factory. Please contact us with your request for this data.

θ_JA and θ_JC values are available for these product series. Please see the Oscillator Thermal Resistance information provided.

IBIS modeling information is available for these product series.

• EV31C3 IBIS Model
• EV31C6 IBIS Model
• EV32C3 IBIS Model
• EV32C6 IBIS Model