CMX998 DATASHEET PDF
As a state-of-the-art design for an integrated CFBL, the CMX improves the . connecting circuitry, details of which are given in the product datasheet. The CMX is an integrated solution for a Cartesian Feedback Loop based linear transmitter. Acting as a direct conversion quadrature mixer from I and Q to RF. CMX datasheet, CMX circuit, CMX data sheet: CMLMICRO – The Product Data Amendment series of documents,alldatasheet, datasheet, Datasheet.
|Published (Last):||18 July 2006|
|PDF File Size:||19.61 Mb|
|ePub File Size:||17.78 Mb|
|Price:||Free* [*Free Regsitration Required]|
Typical changes are variations in antenna VSWR and thermal effects. The error signal produced by the instability detector should be accessed for a particular design and an appropriate threshold set.
The PA device is not protected and enabling this device without the load may irreparably dame the device. Technical Portal No additional information available. The measurements include the effects of the non-ideal PA that is corrected by the Cartesian loop. The wideband noise of the CMX alone at 5MHz offset is typically somewhat better than shown in this plot. Do you have any recommended signal-levels that will allow me to see the CMX at its best? The degradation is due to the gain-expansion caused by the linearity correction for the non-ideal PA.
The output power will decrease once the PA is powered down, and this results in a lower signal level fed back into the CMX The recommended way to avoid this is to power-down the CMX down-converter before powering down the PA. This means a common shift is applied to DC offset correction signal and modulator reference.
The effect is shown in Table 1 below:.
CMX – Cartesian Feedback Loop Transmitter – CML Microcircuits
Are there any particular aspects of power-up or down sequence of the EV that I should be aware of? Datasheets CMX Datasheet rev Can you help explain how the instability detector on the CMX operates and how it can be used?
A simple guide to help users get started evaluating the DE The results from this improved configuration are also shown in Table 1 and although a dataseet degradation is still observed the carrier leakage is still dBc, which datxsheet considered more than adequate for most applications. A simple guide to help users get started evaluating the EV As phase error increases, the instability detector will show a worsening level of out-band energy. These scripts require the following evaluation boards: Both Single Ended and Differential modes are shown.
This App Note discusses these issues using the DE in a worked example. The error amplifier input signal levels will diverge, so the error signal to the up converter will increase, and the signal level to the PA input will also increase.
In the form of a populated Ddatasheet, this flexible platform enables users, using a control interface, to configure and evaluate the CMX to various applications and frequency bands. The CMX includes gain adjustment to make threshold setting easier. The data will appear in the grayed-out data box. Such effects are unlikely to cause a phase shift as large as degrees.
We dagasheet tailor an existing product to your unique requirements Learn more Contact us. Included are forward and feedback paths; local oscillator circuitry including loop phase control; an instability detector and uncommitted op-amps for input signal conditioning. I am looking to develop a high quality non-constant envelope transmitter and am looking to improve the linearity of my current design.
CMX998 – Cartesian Feedback Loop Transmitter
What can I do to ensure a stable carrier leakage when I enable the RF detector? If instability is detected then normal procedure is to power down the transmitter. The instability detector comprises a high-pass filter followed by a peak-detector circuit and this combination indicates the presence of this high frequency energy.
This can over-drive the PA which may over-current and fail. If the loop is set up degrees out of phase the loop will oscillate and will generally produce a maximum level carrier. The datasheeg detector is designed to detect minor phase variations and resultant instability following initial phase correction. If a design supports dynamic loop phase calibration then an instability detector event normally triggers loop re-calibration.
This issue can be greatly reduced if the alternative configuration for applying a bias voltage to the input signal is used, as documented in EV Datasheet version 5 and above. It is important to read the included readme. This effect can be avoided by using BVREF to bias the input signal rather than using a resistor network tied to 3. The modulation accuracy of a CMX transmit is determined by the down-converter feedback path.
There are dataasheet CMX internal registers that are key for this discussion: Using a Cartesian transmitter in TDMA systems can be challenging when supporting multiple modulation formats. This process will continue as the PA output ramps down, with the up converter output and PA input signal level continuously increasing.
The instability detector found on the CMX is a relatively simple mechanism that measures the level of out-of band energy of the feedback cx998. As this is effectively a stable oscillating condition the instability detector will not detect this operating state.
If you continue to use this site we will assume that you are happy with it.