Glossary of Oscillator Terms

Glossary of Oscillator Terms


A systematic average change of an oscillators output frequency as a function only of time. Aging does not include effects of changing environments

Calibration or Adjustment Tolerance

The setting tolerance is the maximum allowable deviation from the nominal frequency at 25°C +- 3°C. It is normally specified in parts per million (ppm)

Duty Cycle

The percentage of each period that a signal is in logic high. This parameter is measured at a specified voltage treshold or at a percentage of the output waveform amplitude

Fall Time

The waveform fall time from high to low transition

Input Current

The amount of current consumption by an oscillator from the power supply, typically specified in milliamperes (mA)


The modulation in phase or frequency of the clock oscillator output


The departure from a straight-line relationship of control voltage to output frequency

Load (fan out)

The capacity of the oscillator to drive other devices

Nominal Frequency

The nominal frequency of the oscillator is expressed in Megahertz ( Mhz) for frequencies of 1.0 Mhz and over. Frequencies may be specified to seven significant figures. If less are specified, then we may assume any digits that follow are zero

Operating Temperature Range

This is the temperature range over wich the quoted temperature stability is specified


The output of a hybrid crystal clock oscillator is a highly stable reference signal

Phase noise

The ratio of the power density of one phase modulation sideband to the total signal. It is usually specified as the single side band (SSB) power density in a 1Hz bandwidth at a specified offset frequency from the carrier. It is measured in dBc/Hz


The frequency shift of a VCXO as a function of control voltage

Rise Time

The rise time of an oscillator is defined as the transition time of the output wave form from a low to a high state. The transition time is measured between 90% and 10% of the falling edge of the switching wave form for TTL and CMOS devices

Start-up Time

The period from the instant voltage is applied to the oscillator until the oscillator output is stabilized

Storage Temperature Range

The temperature range in which the oscillator can be stored without damage, i.e. it will resume operation as normal once it is restored to within its operable temperature range

Temperature Stability

Deviation from the nominal frequency including the frequency deviations due to manufacturing process, temperature, power source variation and load variation


The tristate function allows the oscillator to be isolated from the circuit upon application of a command signal. When this feature is activated, the output of the oscillator is in tristate mode. The tristate mode allows the customer to remove the oscillator from their circuit without physically removing it. Useful for tuning, testing or trouble shooting their board