EV0171 Datasheet, PDF (13/16 Pages) CML Microcircuits – Evaluation Kit User Manual

Evaluation Kit User Manual for CMX017
EV0171
1.6.1.4 FM/FSK Modulator
The modulation input, MODIN, TP1, is designed to be directly driven by a dc-coupled baseband input
signal, to generate a frequency modulated (FM or FSK) RF signal.
Please refer to the CMX017 device datasheet for specifications on maximum modulation
frequency/voltage at the device input (MODIN, pin 18).
The resistors R6 and R5 can be modified depending on the modulation source and required frequency
deviation.
The output impedance at the CMX017 MODOUT pin is typically 50Ω. Using microstrip techniques the
MODOUT track on the 4-layer PCB has been designed to provide a line impedance of 50Ω.
The CMX017 Modulator output signal can be routed to an SMA connector (not fitted), J3, by modifying
components C14, C15, C31 and L7.
1.6.1.5 Power Amplifier
The input/output impedances at the CMX017 PAIN/PAOUT pins are typically 50Ω. Using microstrip
techniques their tracks on the 4-layer PCB have been designed to provide line impedances of 50Ω.
Additional power gain improvement is achieved by employing the simple output matching network, C2,
C3 and L2.
Both amplifier output stages, IPAOUT and PAOUT, must have a dc connection to the supply rail
through RF chokes, L4 and L5.
The evaluation device can be used as a standalone UHF Power Amplifier by modifying components
C14, C15, C31 and L7. The RF signal should be input via an SMA connector (not fitted), J3.
1.6.2 Adjustments and Controls
1.6.2.1 Frequency Control
The trimmer potentiometer, RV2, controls the RF operating frequency. The control voltage derived (0-
3V) from this potentiometer allows the RF operating frequency to be set between 860 - 935MHz. The
frequency control potentiometer draws a typical current of 150µA from the AV_DD3 supply.
1.6.2.2 Gain Control
The trimmer potentiometer, RV1, controls the gain of the CMX017 PA driver. The output power, at the
MODOUT pin, is variable over a 20dB range. The output power is maximum when the CMX017 GAIN
pin is connected to 3V and is reduced by typically 20dB when this pin is connected to 0V.
The gain potentiometer draws a typical current of 150µA from the AV_DD2 supply.
© 1999 Consumer Microcircuits Limited
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