FAST ComTec MCA4A, User Manual

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Hardware Description
3 Hardware Description
3.1 Overview
The MCA4A series is a family of USB 3.0 (compatible with USB 2.0) connected multichannel analyzers. All
settings are software selectable. No jumper (except for the optional ADC full scale ranges), switch etc.
configurations are necessary.
A 1GBit internal DDR2 RAM is configurable as large FIFO buffer for listmode data transfer or as
histogramming memory for onboard spectrum acquisition.
Four onboard discriminators at the four rightmost BNC connectors allow for either positive or negative
GATE / MCS input signals. The input voltage range is from -1.2 V to + 5.0V. The corresponding threshold
voltages are software selectable in steps of 1mV. The input impedance can be switched between 50 Ohm to
GND and 4.7kOhm with either pull-down or pull-up to +3.3V.
Four outputs at the feature connector provide several selectable signals (e.g. SCA, BUSY, etc.) for external
usage.
The legendary 'GO'-line (compatible with other FAST ComTec products) allows for easy synchronization or
triggering of other measurement equipment.
Furthermore a versatile 8 bit digital I/O port allows for a whole bunch of experimental control, monitoring or
whatsoever other tasks. Moreover, the 8 bit digital I/O port can be used for event and spectra tagging to
allow for multi-detector configurations, sequential data acquisition etc.
3.2 Front Panel Connectors
3.2.1 Analog ADC Inputs
The analog ADC inputs are 4 BNC type connectors on the front panel of the MCA4A. Each is paired with a
green LED that indicates that the input is active. They accept negativ or positiv uni-polar or bi-polar signals.
The input signal is continuously sampled by a 125MHz / 16bit (11, 12, 13 bit options are available) analog-to-
digital converter. The converted data is buffered in a 32k x 16bit FIFO for subsequent evaluation. This buffer
FIFO can be segmented in 1, 2, 4 or 8 equal partitions. Each segment holding the complete data of a
detected input pulse for evaluation. This allows for virtually dead-time-less conversion as incoming pulses
can be stored while a previous pulse is still processed by the PHA fitting algorithms. In absolute maximum
mode (no fit) actually no conversion induced dead time exists.
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Fig. 3.1: MCA4 front panel