Saturday, January 8, 2011
【 Weak current College 】 Crystal main parameters 】
Frequency accuracy in nominal supply voltage, nominal load impedance, reference temperature (252 ° c), as well as other conditions remain the same, the technology ' > crystal oscillator frequency relative to its provisions on nominal value of the maximum permissible deviation, i.e. (fmax-fmin)/f0;
Temperature stability other conditions remain the same, in a specified temperature range crystal oscillator output frequency of maximum variation relative to the temperature range of output frequency extremes of allowed frequency offset values, i.e. (fmax-fmin)/(fmax + fmin);
Frequency range by regulating a variable component of crystal oscillator output frequency range.
FM (voltage controlled) features include polls frequently offset, sensitivity, FM FM linearity.
① transferred frequently offset: voltage-controlled crystal oscillator control voltage from the nominal value of the maximum to minimum value output frequency deviation.
② FM sensitivity: voltage-controlled crystal oscillator change units plus control voltage of the output frequency of the change.
③ FM linearity: is an ideal line (PLS) modulation system transmission characteristics of the measure.
Load characteristics of the other conditions remain unchanged, the load changes within the crystal oscillator output frequency relative to the nominal load of the output frequency of the maximum permissible frequency deviation.
Voltage characteristics other conditions remain unchanged, the power supply voltage changes in provisions within the crystal oscillator output frequency relative to the nominal supply voltage of the output frequency of the maximum permissible frequency deviation.
Clutter output signal with frequency without harmonic (except Deputy harmonic) relationship of discrete spectrum components and frequency of the power ratio, expressed by dBc.
Harmonic harmonic components power Pi and carrier power ratio of P0, dBc.
Frequency aging in prescribed circumstances, because components (primarily Quartz resonator) aging and output frequency of the system drift over time. Usually a time interval measured in the frequency difference. For high stability crystal oscillator, because the output frequency in longer working time is approximate linear single direction drift, often with aging rate (unit of time of changes in the relative frequency) to measure.
Day volatility refers to the oscillator warm-up time through regulations, every hour, measurement time, 24 hours of continuous measurements, the test data by S = (fmax-fmin)-calculation, get/f0 daily fluctuation.
Power on the system properties in the warm-up period, the oscillator frequency is the maximum change value, v = (fmax-fmin)/f0 said.
Phase noise in the frequency domain measurements of short-term stability. With sideband noise and carrier-noise ratio (f), (f) and noise fluctuations spectrum density S φ (f) and frequency fluctuation spectrum density Sy (f) directly related to the following type:
F-Fourier frequency or deviate from the carrier frequency; f0-carrier frequency.