MAX2620EVKIT Maxim Integrated Products, MAX2620EVKIT Datasheet - Page 2

• Manufacturer Part Number: MAX2620EVKIT
• Description: RF Modules & Development Tools MAX2620 EVAL KIT MAX2620 EVAL KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX2620EVKIT

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1) Verify that the shunt on jumper SHDN is installed
2) Connect the spectrum analyzer to either OUT or
3) Connect a +2.7V to +5.25V supply across V
4) Connect the tuning voltage supply to either VCONT
1) Using the spectrum analyzer, observe the voltage-
2) Allow the oscillator to operate for about 5 minutes
3) Center the fundamental on the spectrum analyzer
4) Set the spectrum analyzer for single sweep. This
5) Set the marker on the waveform’s peak.
MAX2620 Evaluation Kit
2
____________Connections and Setup
____________________________Analysis
between pins 1 and 2 (SHDN = V
the shunt between pins 2 and 3 (SHDN = GND)
puts the MAX2620 into low-current shutdown mode.
OUT. Connect a 50Ω terminator to the output (OUT
or OUT) not connected to the spectrum analyzer.
GND. V
or JU1. This supply should be positive when refer-
enced to ground.
HP8561E spectrum analyzer, or equivalent high-
sensitivity spectrum analyzer with approximately
3GHz frequency range. Contact the instrument
manufacturer for information regarding phase-noise
measurement capabilities.
Digital multimeter (DMM) to monitor DC supply and
VCONT, if desired
Male SMA 50Ω terminator
Network analyzer such as HP8753D (required only
if additional device characterization for oscillator
tank design at other frequencies is desired)
_______________________________________________________________________________________
controlled oscillator’s output. With 1.5V applied to
VCONT, the fundamental output frequency will be
near 900MHz. The output power level will be
approximately -2dBm at OUT, or -12.5dBm at OUT.
Varying the voltage applied to VCONT between 0V
and V
quency. (Increasing the voltage applied to VCONT
increases the frequency, and vice versa.) The typi-
cal tuning range is a 30MHz band centered near
900MHz with VCONT between 0.5V and 3V. To
avoid damaging the varactor, do not apply voltages
greater than 15V to VCONT. (The varactor on the
EV kit board has a 15V breakdown specification.)
to thermally stabilize the frequency. Since the fre-
quency is not phase-locked to a reference, this
minimizes frequency drift and measurement error.
and set the frequency span to 100kHz.
minimizes errors due to oscillator frequency drift.
CC
CC
changes the fundamental oscillation fre-
should be the most positive terminal.
CC
). Placing
CC
to
6) Set another marker to measure the difference
7) Under the Marker function, select marker noise and
8) Verify that the resolution bandwidth is 1kHz.
9) Verify that the video bandwidth is 1kHz.
10) Read the measurement directly from the screen.
_____________________________Outputs
The MAX2620 EV kit is assembled with OUT matched
to 50Ω (at approximately 900MHz) using L3 and C13.
OUT is resistively pulled up to the supply with a 51Ω
resistor, R5. R5 provides a simple broadband 50Ω out-
put match but offers less output power than OUT. The
EV kit provides additional component pads at R4, C14,
L4, and C11 to accommodate any output match config-
uration for OUT and OUT. Refer to the Output Matching
Configuration section in the MAX2620 data sheet for
more information.
The resonator tank circuit is critical in determining VCO
performance. It typically contains a varactor (voltage-
variable capacitance) for voltage-tuning the center fre-
quency. For best performance, use high-Q components
and choose values carefully.
The external resonant circuit on the MAX2620 EV kit
has been designed to operate near 900MHz. To syn-
thesize the component values for other frequency
ranges, use the following procedure.
On the EV kit, C3 and C4 are feedback capacitors that
set the oscillator’s negative resistance and impedance.
Their values have been chosen to provide adequate
performance over a 650MHz to 1050MHz frequency
range. To optimize the values of these components for
a specific application, refer to the Feedback Capacitors
section in the MAX2620 data sheet.
Measure the MAX2620 TANK pin’s input impedance
with feedback capacitors C3 and C4 but without the
resonant circuit. This measurement takes into account
parasitic circuit elements that are specific to board lay-
___________Resonator and Varactor
between this peak and the signal level at 25kHz off-
set from the peak. (Phase noise can be observed at
frequencies other than 25kHz offset.)
turn it on. This automatically scales the spectrum
analyzer’s output to take into account the resolution
BW filter’s non-ideal characteristics. If your spectrum
analyzer does not offer this feature, contact the man-
ufacturer for proper scaling for noise measurements.
Phase noise will be about -110dBc/Hz. In some envi-
ronments that have ambient pulse noise, this mea-
surement may be difficult to achieve without addi-
tional shielding or the use of a shielded enclosure.