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.

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The results from this daasheet configuration are also shown in Table 1 and although a small degradation is still observed the carrier leakage is still dBc, which ratasheet considered more than adequate for most applications.

If the loop becomes unstable due to phase inaccuracies the feedback loop will tend to spill energy out-of band. The effect is shown in Table 1 below: A simple guide to help users get started evaluating the DE The degradation is due to the gain-expansion caused by the linearity correction for the non-ideal PA.

The modulation accuracy of a CMX transmit is determined by the down-converter feedback path. 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. These scripts require the following evaluation boards: Are there any particular aspects of power-up or down sequence of the EV that I should be aware of?

In cmx9998 form of a populated PCB, this flexible platform enables users, using a control interface, to configure and evaluate the CMX to various applications and frequency bands. This effect can be avoided by using BVREF to bias the input signal rather than using a resistor network tied to 3. We use cookies to ensure that we give you the best experience on our website.


This means a common shift is applied dwtasheet DC offset correction signal and modulator reference. This can over-drive the PA which may over-current and fail.

Using a Cartesian transmitter in TDMA systems can be challenging when supporting multiple modulation formats. The PA device is not protected and enabling this device without the load may irreparably dame the device.

CMX998 – Cartesian Feedback Loop Transmitter

The CMX includes gain adjustment to make threshold setting easier. If instability is detected then normal procedure is to power down the transmitter.

If a design supports dynamic loop phase calibration then an instability detector event normally triggers loop re-calibration. There is nothing specific to be aware of when powering the EV up for the first time, however it is very important to ensure that a 50ohm load is attached to J9 before enabling the power amplifier.

CMX – Cartesian Feedback Loop Transmitter – CML Microcircuits

This process will continue as the PA output ramps down, with the up converter output and PA input signal level continuously increasing. 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.


If the loop is set daasheet degrees out of phase the loop will oscillate and will generally produce a maximum level carrier. Technical Portal No additional information available. Note that a different loop-filter might be required for the datashee and kHz channels.

CMX Datasheet(PDF) – CML Microcircuits

I am looking to develop a high quality non-constant envelope transmitter and am looking to improve the linearity of my current design. If you continue to use this site we will assume that you are happy with it. Can you ratasheet explain how the instability detector on the CMX operates and how it can be used?

Such effects are unlikely to cause a phase shift as large as degrees. There is a preferred method of dattasheet down the EV to also avoid damage to the power amplifier PA.

A simple guide to help users get started evaluating the EV This App Note discusses these issues using the DE in a worked example.

The instability detector is designed to detect minor phase variations and resultant instability following initial phase correction. Datasheets CMX Datasheet rev The instability detector found on the CMX is a relatively simple mechanism that measures the level of out-of band energy of the feedback loop.

EV high resolution schematics and component overlay. Three scripts for evaluating performance of a multi-mode modem using the DE