EV0171 Datasheet, PDF (12/16 Pages) CML Microcircuits – Evaluation Kit User Manual

Evaluation Kit User Manual for CMX017
EV0171
1.6 Detailed Description
The EV0171 Evaluation Kit comprises a single board containing the CMX017 UHF FM/FSK
transmitter, frequency and gain potentiometers, VCO tank circuitry and miniature control switches.
A multi turn potentiometer allows the user to select an RF operating frequency between 860-
935MHz. The operating bandwidth and centre frequency can be adjusted by simply modifying the
VCO tank components.
The board is powered from a single 6 - 12 V dc power supply. Regulation circuitry sets the
analog(AV_DD) supply for 3V operation. CMX017 supply currents may be measured by removing
appropriate jumpers.
A low profile 2-way DIL switch controls the device enable lines, to obtain CMX017 powersave and
zero-power modes.
Links, test points and SMA connector provide access to various points in the circuit.
This open-loop configuration is not recommended for the majority of customer applications. A
closed-loop PLL design is required to improve controllability and overcome stability and drift
problems.
External PLL circuitry could be connected to test points TP8 (OSCOUT) and TP9 after removal of
RV2.
1.6.1 Hardware Description
1.6.1.1 Operating Voltage
The supply regulation circuitry contains a single regulator and associated components to provide the
analog supply (AV_DD). The operating voltage is set to 3.0V.
The supply feed is split three ways to reduce interference and to enable the user to separately
measure various device/circuitry currents.
The supply regulation can be bypassed and external supplies applied, via jumpers JP1-JP3.
Note, due to the inductors dc resistance which is approximately 0.5Ω (100nH), small voltage drops will
occur across inductors L3 and L1.
1.6.1.2 Current Measurement
Supply currents for the evaluation device and other board circuitry can be measured by removing the
appropriate jumper and replacing it with a multimeter.
1.6.1.3 VCO Tank Circuitry
The tank resonator circuit is formed by two capacitors, C16 and C19, RG405 coaxial resonator, PR1,
and varacter diode, D1, which is driven by the frequency control potentiometer, RV2.
The dc control voltage derived from the frequency control potentiometer, RV2, can be measured at
TP9. Alternatively the potentiometer can be removed and control voltage applied to the VCO tank
circuitry via the test point TP9.
© 1999 Consumer Microcircuits Limited
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