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Bergoz Beam Position Monitors, BPM
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 The
Bergoz Beam Position Monitor Analog Front End (BPM-AFE) is an analog front end to process RF signals from beam position pickup electrodes. It delivers an output signal which can be directly entered into fast 14-bit ADCs. It is specially developed for transfer lines and linacs. It can be customized to any RF frequency up to 1 GHz.
For Beam Position Monitoring in electron and positron
Storage Rings, please refer to the MX-BPM.
The BPM-AFE is in use at <<Insert customers using
the LR-BPM here>>.
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BPM-AFE features |
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Non-interceptive beam position measurement |
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Four input signals are processed in parallel, allowing fast, single-pass position measurement |
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Customizable to any bunch frequency up to 1GHz |
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Mezzanine board to PCI specifications |
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Input signals are down-converted by independent superheterodyne receivers to an intermediate frequency (IF)
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The IF output signals are differential and galvanically isolated, for direct input into fast ADC (e.g.AD6644) |
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IF bandwidth adjustable by separate independent highpass and low-pass filters provide flexibility |
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Output signals are adjustable up to 4Vpp to take advantage of full ADC input aperture |
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High phase accuracy and low harmonic distortion by current feedback amplifiers |
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Low power dissipation and temperature drift are achieved with passive mixers |
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Excellent in-band transient response Abuse-tolerent by design |
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Hot-swappable |
Signal Processing
The input signals that are fed in to each superheterodyne channel can either be the Calibration signal or the signal from the lobe. The selwction is controlled by the lobe, Input and Calibration switches, and each of the channel switches are controlled individually.
Calibration signals are balanced to identical levels for each receiver, and can be sent to any lobe for detection by another channel as selected by the state of the control switches.
Calibration signal frequency is independent of the superheterodyne receiver frequency
Switch-selected input signals are summed to produce a phase reference signal. Each channel is otherwise processed independently. Two successive trap filters reject unwanted harmonics, and a passive double-balanced mixer processes the signal with a common Local Oscillator (LO) signal. The common LO signal is distributed to each mixer after buffering. The resulting Intermediate Frequency (IF) is filtered by two cascaded high-pass and low-pass filters to reject the unwanted mixing products.
The IF filtered signal is amplified by two stages of high gain x bandwidth current-feedback amplifiers. The first stage can be switched between two gain levels, while the second stage gain is adjustable by potentiometer in a range 1:4.
A balun at the output produces a balanced signal with floating ground reference from each single-ended IF signal. |
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