Vector Modulator AMC board
Marcin Smelkowski
marcin.smelkowski@desy.de
Presentation is based on
„Draft Requirements for a new Vector Modulato On a AMC Card” by Henning Weddig
Warsaw University od Technology
PERG – ISE
3.12.07
Purpose of VM board
„
Changing the amplitude and phase of the 1.3GHz reference signal from the
master oscillator. Then modulated signal goes via a preamplifier to the
klystron which then drives the accelerating cavities.
„
The generation of the LO signal for the down converters.
„
Generation of new frequencies.
Marcin Smelkowski
marcin.smelkowski@desy.de
Warsaw University of Technology ISE - PERG
Block diagram
Marcin Smelkowski
marcin.smelkowski@desy.de
Warsaw University of Technology ISE - PERG
Sub-Modules
„
DAC – two-channel AD9777 – convertion of digital I and Q signal
„
Interface Between AD9777 and ADL5385 with 50 Ω resistors to ground to establish the 500 mV DC Bias for the
ADL5385 baseband Inputs. Also resistor is placed in shunt between each side of the differential pair. It has the
effect of reducing the ac swing to 1.4 V p-p differential without changing the dc bias already established by the 50
Ω resistors.
„
5-pole Chebychev filter with a corner frequency of 36 MHz - When driving a modulator from a DAC, it is
necessary to introduce a low-pass filter between the DAC and the modulator to reduce the DAC images
„
Vector Modulator - ADL5385 – 50 to 2200 MHz, Noise floor -159dBm/Hz, Sideband suppression -44dBm and
Carrier feedthrough -36 dBm while unadjusted. After optimization Ssup=-50dBm and Cft=-61dBm can be
achieved. Callibration can be simply done by adjusting the DAC output currents. By changing the DAC’s registers
the levels and offsets of those currents can be control.
„
4 x Power Detector – AD8362 Input dynamic range of >60 dB: −52 dBm to +8 dBm in 50 Ω, Linear-in-decibels
output, scaled 50 mV/dB They are placed to detect power of LO, RF after amplifier, RF after attenuator and RF
after RF-Gate.
„
Voltage switch - ADG733 + 16 bits ADC with SPI - AD7683 – to make the readouts from choosen power
detector. There is no need of making it from all detectors at the same moment.
„
Low noise amplifier HMC374 – gain of 13dB, low noise figure: 1.5dB, high output IP3: +35 dBm
„
Attenuator – HMC305 - 0.5 dB LSB Steps to 15.5 dB with control done by SPI
„
RF-Gate – HMC349 + OR logic gate – high isolation, non-reflective DC to 4 GHz switche plus aditional external
logic to calcualate the on/off signal
„
Leds and SMA inputs/outputs on the front panel (prototype board)
Marcin Smelkowski
marcin.smelkowski@desy.de
Warsaw University of Technology ISE - PERG
Summary
Controller Provides:
- self diagnostic and callibration
- in case of carrier break-down sterring signal is taken form Feed-Forward tables in EEPROM
- a lot of logic for custom algoritms
- on-line mesuare of power at every stage of signal procesing
- no output power if the system is off
- sending the mesuared values to the main FPGA
- diagnostic readouts
Stage of work:
- all schematics are already done
- layouts are half-made and are expected to be finished by the end of the year
- it is expected that by the end of the February the prototype board will have been started and tested
Background:
- all schematics of AMC Vector Modulator board were made as a result of research and development of the first
version of Vector Modulator board for ACB1 board
Marcin Smelkowski
marcin.smelkowski@desy.de
Warsaw University of Technology ISE - PERG
Thank You For Your Attention, All Comments And Remarks
Marcin Smelkowski
marcin.smelkowski@desy.de
Warsaw University of Technology ISE - PERG