EV9900 Datasheet, PDF (15/27 Pages) CML Microcircuits – Evaluation Kit

Evaluation Kit for CMX990
EV9900
6. Detailed Description
The CMX990 datasheet (not included but available at www.cmlmicro.com) should be referred to
for a detailed description of the CMX990 device.
The EV9900 functionality includes:
• Demonstration of the CMX990 RF functionality at ≈400MHz or ≈800MHz
• Implementation of the 1^st receive mixer bypass mode
• Demonstration of EN 300 113 receive performance in mixer bypass mode
• Interfaces that allow the card to be connected to a host µController, to allow real-time control,
or to a PC (a separate interface may be required)
• An interface allowing the connection of an external reference clock
In summary, the EV9900 allows the user to create experiments to investigate all aspects of the
CMX990 device. The EV9900 is designed to allow user modification, to support detailed
investigation of each user’s specific and different applications.
6.1 Hardware Description
Front End LNA
The PCB includes a broad band MMIC LNA operating 400MHz to 1GHz, for evaluation at
different operating frequencies. Also provided is an LNA using TR5, which is designed for 440-
453MHz and to meet EN 300 113 requirements. The LNA includes the front end image reject
filtering (L26, L27, C186, C187, C188, C189, C192, C193 and C194). This is not configured in
the default version of the EV9900.
1^st Rx Mixer
By fitting or not fitting certain capacitors the user is able to select the CMX990 image reject mixer
or an external mixer (U15) compliant with EN 300 113 requirements. The external mixer is a
diode ring type. U15 is followed by a buffer (TR4). This buffer has a flexible configuration to
allow optimisation by the user if required. The outputs of the mixer sections may be connected to
test equipment or to the IF filter section. (Note: if the user wishes to interface to test equipment
they will need to match the ports to the impedance of the test equipment, typically 50Ω).
IF Filter
The IF filter (F2) is a 45MHz 4-pole crystal filter. The pass-band of the filter fitted to the EV9900
is +/-6kHz, however other filters are available in the same package outline, offering different
bandwidths. Correct matching of the filter is necessary to achieving optimum performance.
Reference Oscillator
A 19.2MHz VCTCXO is provided on the PCB. If C4 is removed and C3 fitted an alternative clock
source can be applied to J1.
© 2005 CML Microsystems Plc
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UM9900/1