In this application note transceiver refers to these types of transceivers.
Vcxo circuit design.
This is almost invariably achieved using varactor or varicap diodes.
Included is a temperature sensor that when the temperature changes will apply a small correct voltage to a varactor which then produces a frequency that is equal and opposite to the change in frequency produced by the temperature.
Vcxo clock generators are used in many areas such as digital tv modems transmitters and computers.
Exploring the vcxo circuit.
This application note provides the general structure for a vcxo clk generator key performance measurements guidelines for pcb design and a test setup for max9485 a vcxo clk gen chip for mpeg2 and ac 3 audio applications.
Which can act as vco.
This must be taken into consideration during the electronic design phase to ensure a vcxo with a suitable.
Vcxo clock clk generators have been used in various applications such as digital tv digital audio adsl and stb.
This is almost invariably achieved by using varactor or varicap diodes.
Oscillator circuit nonlinearities cause low frequency noise components to be up converted and to appear as noise sidebands on the vco output.
Consideration of the circuit components used and the layout all play a role in determining the performance.
The basic circuit for an vcxo comprises a standard crystal oscillator but with an electronic means of tuning or pulling the frequency slightly.
There are many types of vco circuits.
Apart from that there are dedicated ic packages like lm566 lm567 etc.
A very basic one can be built by just utilising a capacitor inductor and resistor to make a tank circuit.
A common design requirement is to frequency or phase lock a transceiver output to an input source known as loop recovered or slave timing.
The design of a high performance voltage controlled oscillator vco is not is not a trivial task.
This requires sound theoretical design followed by careful choice of all the components and then a good pcb layout.
Tcxos use an element known as a voltage controlled crystal oscillator vcxo.
Also op amps multivibrator transistors 555 timers can also be utilised to build oscillating circuits.
Misbehaving vcxo will bring down the whole system the trick will be to prove that the vcxo is the culprit easier said than done.
Design parameters for a vcxo clock generator are tuning voltage range center frequency frequency tuning range and the timing jitter.
A clock generator is an oscillator that provides a timing signal to synchronize operations in digital circuits.
Crystal oscillator vcxo circuits by utilizing functionality within each serial gigabit transceiver.
Although this statement is intuitively obvious quantifying this mechanism is much more complex.
In most vcxos a pair of back to back diodes is placed across the crystal.
