Erläuterung MEMS Oszillatoren
Introduction
Micro Electro Mechanical Systems or MEMS as it is commonly known is the latest technology to be used in the Frequency Products market as an alternative to quartz based devices.
MEMS devices use a “silicon-beam” rather than quartz as the frequency control element which provides advantages such as small package size and good environmental performance for shock and vibration.
IQD’s series of MEMS devices use an internal MEMS resonator and a factory programmable oscillator circuit to provide the output frequency required by the customer.
Our range of devices includes clock oscillators (IQMS series) and voltage controlled devices (IQMV series) in 4 package sizes and 4 supply voltage options.
The IQMS-100 & IQMV-300 series of oscillators provide standard specification performance while the IQMS-200 & IQMV-400 series provide enhanced performance including low jitter, better frequency stability and for the IQMV series, a choice of pullability options.
Fast Make Capability
Due to the fact that MEMS oscillators are programmable, we are able to offer a fast make capability for this range of devices
Specification
A typical surface mount MEMS 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 clock oscillator frequency should be specified 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 16.6666.
Model Number
The model number incorporates information which describes output compatibility and holder style.
Frequency Stability
The frequency stability of a surface mount oscillator includes the initial adjustment tolerance at room temperature and the tolerance over operating temperature range. This value is specified as ‘parts per million’ (ppm) and is available in the ranges as shown below.
The following codes apply:
A = ±25ppm
B = ±50ppm
C = ±100ppm
Operating Temperature Ranges
–10 to 70°C
–20 to 70°C
–40 to 85°C
Although in general clock 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.
Frequency Pullability (IQMV-300 & 400 series)
As standard the centre trim voltage is +0.8V. The pullability is specified as the change in frequency when the trim voltage is varied by ±0.8V. This value is specified in ‘parts per million’ (ppm). Please see individual data sheets for further details.
Tri-State/Standby
The IQMS series of MEMS has the option of specifying either Tri-State (code TS) or Standby (code ST) as a function of the output signal. When in tri-state mode the output goes to the high impedance state while in standby mode the internal oscillator stops and the output signal goes to a low level.
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.