# Terms, definitions and characteristics

Oscilátors types |
Definitions |

CXO ( PXO, MXO ) | Single crystal oscillator, has frequency stability of the crystal units |

VCXO | Voltage controlled crystal oscillators, can change the oscillation frequency with external voltage |

TCXO | Temperature compensated crystal oscillator, compensated for frequency changes caused by the external temperature |

OCXO | Oven control crystal oscillator, includes a temperature stabilized resonator |

Term |
Unit |
Definitions |

Nominal frequency f_{o}( Output frequency ) |
[MHz] |
Nominal value of the frequency described in specifications. It is the output
frequency at the standard temperature (usually 25^{o}C), specified power
supply voltage and load. |

Frequency stability | [ppm] | The frequency range before and after specific ambient conditions such as temperature, power supply input variations, load variations, operation time (aging, long-term stability), etc. |

Aging ( Long-term stability ) |
[ppm/year] |
The frequency deviation with the lapse of time during normal operation |

Frequency stability vs. supply voltage |
[ppm/V] | Frequency deviation when the power supply input voltage is varied. |

Frequency stability vs. mechanical environment | [ppm] | Specified by the deviation before and after shock, dropping, sine wave vibration, constant acceleration, etc. applied. |

Frequency stability vs. load |
[ppm] / Z |
Frequency deviation when the load conditions have varied from the standard value. |

Operation temperature range |
[ °C ] |
The temperature range which the oscillator can safely operate. The frequency tolerance cannot be maintained outside the specified limits. |

Storage temperature range |
[ °C ] | Maximum absolute temperatures allowed in the discharged state. Exposure to temperatures outside these limits may result in damage. |

Supply voltage | [ V ] | The DC input voltage necessary for oscillator operation. |

Input current | [ mA ] | The amount of current consumption by an oscillator from the power supply. |

Deviation (for VCXO type) |
[ V ] | This range indicates the width of output frequency that can be adjusted by control voltage. |

Start-Up time | [msec], [sec] |
The specified time from oscillator power-up to the time the oscillator reaches steady state oscillation. |

Logic levels | [ 0, 1 ] | Defined as the Output Voltage Logic High or "Logic 1" and the Output Voltage Logic Low or "Logic 0". |

Rise time ( Tr ) | [ µs ] | The time taken for the output waveform to change from the low voltage level to the high voltage level. |

Fall time ( Tf ) | [ µs ] |
The time taken for the output waveform to change from the high voltage level to the low voltage level. |

Duty cycle ( symmetry ) |
[ % ] | Measured at +1.4V for TTL oscillators and ½ Vdd level for universal, HCMOS and CMOS oscillators, this is the ratio of full and half cycles. |

Internal Trim | This range indicates the width of frequency that can be adjusted by a trimmer built in the oscillator. | |

Phase noise | The frequency domain measure of short term frequency stability of an oscillator. | |

Short term stability | The random fluctuations of the frequency of an oscillator over short periods of time. |

## Measuring circuit

**Cliped Sine**

C

R

_{L}= 10 pF (including fixture and probe capacitances)R

_{L}= 10 kΩ- CMOS

C

_{L}= 10 pF (including fixture and probe capacitances)- TTL

C

*T.P = Test Point

_{L}= 15 pF max (including fixture and probe capacitances)*T.P = Test Point

## Other courses

- Output waveform

- Phase noise

- REFLOW diagram