AMC vector modulator card for the LLRF system

The LLRF system used for linear accelerator control uses a vector modulator module to change the amplitude and phase of the electromagnetic field in accelerating cavities. Recent system development assumes using of the modular xTCA standard as a hardware platform for the LLRF components. The AMC modules are specified by the xTCA standard. The ATCA version of the LLRF system uses double-board AMC modules where one board contains universal digital hardware, and the second board the functional, analog part. This paper describes the conception, design and performance test results of the analog AMC board prototype with 1.3 GHz Vector Modulator functionality. The board can be used to modulate a 1.3 GHz signal provided from either the AMC connector or from a front-panel SMA connector. Integrated programmable attenuator, power amplifier and power level monitoring circuits allow for automatizing of the device calibration and test procedures. A Remotely controlled RF gate was foreseen for accelerator system protection. The board contains two fast, high-precision DACs which are driven in real time by the digital part of the AMC module.