Small Cells: Femtocell — Microcell — Picocell

The femtocell, a miniature communication base station, has placed extreme demands on the reference oscillator for timing solution. To provide a seamless interface to the macro base stations, the frequency reference device of the femtocell must provide similar performance but at a reduced size and a greatly reduced cost.

A few years ago, the needed performance could only be achieved with an Ovenized Crystal Oscillator (OCXO) where the oven would hold the crystal at a fixed temperature. With the evolution of precision analog CMOS ICs and superbly processed quartz crystal resonators, similar performance can now be achieved with our Temperature Compensated crystal oscillators (TCXOs). These TCXOs are simple in construction, exceptionally reliable and result in a cost effective timing device.

Pletronics has worked with the Femtocell chip set makers to provide a frequency control device that will meet the industry needs. Pletronics devices work well with Airvana, Percello and picoChip chip sets.

Pletronics TCD4 Series for Femtocell Applications

Parameter Test Condition Specification
Frequency stability versus temperature Fixed supply voltage and load 0°C to 80°C ±100ppb
Holdover for 24 hours Includes temperature change, supply voltage and short term aging ±100ppb
Long term frequency stability Frequency change versus time at 25°C 1 month ±175ppb
1 year ±1 ppm
5 years ±3 ppm
Vcontrol Pull Ability Vcontrol from 0.5 to 3.0V ±5 ppm minium

 

TCD4 Femtocell Performance

Graph of typical TCD4 Femtocell Performance
Graph of typical TCD4 Femtocell Performance

The one challenge that the quartz crystal technology can not solve is the long term aging of the resonator. This aging must be corrected by referencing the TCXO to a precision timing signal. The TCXO's holdover capabilities of 24 hours, retention of the precise output frequency, permits using the IEEE 1588 Precision Time Protocol standard via the Femtocell's internet connection. Use of GPS can also provide the needed correction for aging.

Pletronics has also Ovenized Crystal Oscillators (OCXOs) available for Enterprise or corporate FemtoCell/PicoCell/MicroCell applications.

 

Download Datasheets

Model Frequency (MHz) ±100ppb over the Temperature range
TCD4012 19.2, 26.0 +20°C to +60°C
TCD4025 19.2 0°C to 70°C
TCD4027 26.0 0°C to 70°C
TCD4029 26.0 0°C to 80°C
TCD4032 19.2 0°C to 80°C

Contact Pletronics: Our support staff with many years of experience in supplying precision frequency control devices are available to assist you in your application.