Transmitter Rf Port Impedance Matching Network - Analog Devices ADRV9001 User Manual

Preliminary Technical Data

TRANSMITTER RF PORT IMPEDANCE MATCHING NETWORK

TX1± and TX2± Impedance Matching Network
For the TX path, the ADRV9001 evaluation board utilizes both the top and bottom layers of the PCB evaluation platform to
accommodate two balun footprints. The 0805 footprint accommodates the high frequency narrowband baluns while the backside
accommodates the larger AT224-1A case style transformer.
The ADRV9001 evaluation board provides two options in providing the DC common mode bias for the TX outputs. For transformers
that provide a DC feed pin, this can be used to bias the TX output. For transformers that do not provide a DC feed pin, the TX outputs
are biased to 1.8V through pull up inductors. Only one bias option should be chosen, and provisions should be made to disable the
unused path.
The PCB traces of the evaluation board were included in the simulation when designing the impedance match. Figure 178 and Table 87
provides impedance matching networks specific to the ADRV9001 evaluation board. The component values apply to TX1± and TX2±.
Placement of C335 should be as close to dc feed pin of balun T302 as its purpose is to eliminate TX spectrum spurs and dampen the
transients. Ground terminal of C335 should be tied to a ground plane and the cap should be oriented in the same direction of ground
plane surrounding TX input trace so that the return current forms as small a loop as possible with the ground plane.
C309
DNI
VANA2_1P8
L309
DNI
TX2_OUT–
L311 C311
DNI DNI
TX2_OUT+
RX2B_DC
L309
DNI
C310
DNI
VANA2_1P8
IMPEDANCE CHARACTERISTICS:
Tx OUTPUTS = 50Ω DIFFERENTIAL,
BALUN = 500Ω SET TO 500Ω DIFF
NOTES
1. MATCHING COMPONENTS APPLY TO RX1B± AND RX2B±
0 0.5 1.0
Figure 177. Insertion Loss – Simulated RX1(2)A Port – Red Curve RX1(2)B Port – Blue Curve
AGND
L312
DNI
R367
R312
DNI
DNI
C351
DNI
0805 FOOTPRINT
3
L339 C339
L313 BAL_OUT1
DNI DNI DNI
4
BAL_OUT2
R313 R368
GND_DC_FEED_RFGND
DNI DNI
R368
0Ω
C313
VANA2_1P8 DNI
DNI
C333 C334 C335
10µF 0.1µF 0.1µF
AGND
Figure 178. TX1 and TX2 Impedance Matching Network
Rev. PrA | Page 197 of 253
1.5 2.0 2.5 3.0
FREQUENCY (GHz)
BALUN LOCATED
ON BOTTOM
OF THE BOARD
C346 T312
TCM1-13M+
DNI
TX2_BAL–
1
SEC
3
C347 2
NC
DNI
TX2_BAL+
BALUN LOCATED
L341
ON TOP
DNI
OF THE BOARD
C341
1 DNI
RFO_2
T302
UNBAL_IN
DNI
R341
GND NC_6
DNI
2 5 6
3.5
6
PRI
4
L348 R348 C348
L315
DNI DNI DNI
DNI
C315
DNI
R315
DNI
L314 C314 L316
DNI DNI DNI
UG-1828
RF OUTPUT 2
J302
AGND
C316
DNI