CN-0285 Datasheet, PDF (1/5 Pages) Analog Devices – Broadband Low Error Vector Magnitude (EVM) Direct Conversion Transmitter

Circuit Note
CN-0285
Circuits from the Lab™ reference circuits are engineered and
tested for quick and easy system integration to help solve today’s
analog, mixed-signal, and RF design challenges. For more
information and/or support, visit www.analog.com/CN0285.
Devices Connected/Referenced
ADF4351 Fractional-N PLL IC with Integrated VCO
ADL5375 Wideband Transmit Modulator
ADP150
Low Noise 3.3 V LDO
ADP3334 Low Noise Adjustable LDO
Broadband Low Error Vector Magnitude (EVM) Direct Conversion Transmitter
EVALUATION AND DESIGN SUPPORT
Circuit Evaluation Boards
CN-0285 Evaluation Board (EVAL-CN0285-EB1Z)
Design and Integration Files
Schematics, Layout Files, Bill of Materials
CIRCUIT FUNCTION AND BENEFITS
This circuit is a complete implementation of the analog portion
of a broadband direct conversion transmitter (analog baseband
in, RF out). RF frequencies from 500 MHz to 4.4 GHz are
supported using a phase-locked loop (PLL) with a broadband,
integrated voltage controlled oscillator (VCO). Harmonic filtering
of the local oscillator (LO) from the PLL ensures excellent
quadrature accuracy, sideband suppression, and low EVM.
5.5V
1µF
ADP150
V_VCO
3.3V
1µF
V_DD
FREF_IN
16 17 28 10 4 26 6 32
V_VCO DV_DD AV_DD CE PDB_RF V_P SDV_DD
1nF 1nF
29 REFIN
51Ω
1 CLK
2 DATA
RF_OUTB+ 14
RF_OUTB– 15
3 LE
ADF4351
RF_OUTA+ 12
V_VCO
Z_BIAS
4.7kΩ
22 R_SET
RF_OUTA– 13
V_TUNE 20
CP_OUT 7
SW 5
CP_GND SD_{GND AGND} A_GNDVCO DGND
8
31 9 11 18 21 27
2.7nF
Z_BIAS
1kΩ
47nF
360Ω
680pF
5.5V
1µF
I/Q SMA INPUTS
IBBP
IBBN
ADP3334
1µF
5.0V
VPS1, VPS2
ADL5375
LOIP
LOIN
QUADRATURE
PHASE
SPLITTER
QBBP
QBBN
I/Q SMA INPUTS
Figure 1. Direct Conversion Transmitter (Simplified Schematic: All Connections and Decoupling Not Shown)
RFOUT
Rev. 0
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