Specifying VCXOs
A typical VCXO specification reads like this:
The following notes define each element of the specification.
Frequency
Frequency is normally specified in kilohertz (kHz) up to 999.999kHz and in megahertz (MHz) from 1.0MHz. All our computer-generated transaction documents follow this standard convention automatically.
The VCXO frequency should be described to seven significant figures. If seven significant figures are not used, we assume that any figure that might follow those given may be taken as zero. Thus a frequency given as 16.6MHz will be taken as 16.60, not 16.66667.
Model Number
The model number incorporates information which describes output compatibility and holder style.
Frequency Stability
The frequency stability of a VCXO includes the initial adjustment tolerance at room temperature (with the control pin set to centre trim voltage: e.g. 2.5V) and the stability over the operating temperature range. This value is specified as ‘parts per million’ (ppm) and is available in three ranges; ±25ppm, ±50ppm and ±100ppm.
For standard oscillators the following codes apply:
A = ±25ppm
B = ±50ppm
C = ±100ppm
Frequency Pullability
The pullability is specified as the change in frequency when the voltage control is varied. This value is specified in ‘parts per million’ (ppm) and is available in various ranges depending upon the model number. The pullability may be specified as either APR (absolute pulling range) or relative pulling.
APR is the minimum pulling from nominal after an allowance is made for frequency shift due to factors such as temperature, ageing, supply voltage, load variation and environmental effects.
Operating Temperature Range
Standard operating temperature ranges for VCXO’s are:
0 to 70°C
–20 to 70°C
–25 to 85°C
–40 to 85°C
Although in general oscillators will continue to operate outside their normal temperature range with a degradation in frequency stability, damage can result if the temperatures reached are excessive.
For other temperature ranges please contact the IQD sales office.
Packaging Code
Tape and Reel packaging is available as an option on many of the products outlined in this chapter.
Unless individual data sheets state Tape and Reel packaging, items will be bulk packed. Please note: only complete reels are sold.
BU = Bulk packed
TR = Tape & Reel packed
Additional Text Code
If the product is non-standard, the letter ‘T’ will appear at the end of the product specification. This refers to additional text on the quotation/sales order to identify the non-standard requirements.
Outline Drawings
Dimensions on the oscillator outline drawings are shown only as a guide. Precise dimensions of oscillator holders are available from our Engineering Department upon request. All dimensions are shown in mm and are nominal unless otherwise stated.
Marking
Product will be marked as detailed in the individual data sheets. Where space is limited some or all of the information will be omitted/truncated at IQD’s discretion. Full product description will be found on the individual batch packaging.
Ordering Information
See individual data sheets