Isolation Techniques Used On The Adrv9001 Evaluation Card - Analog Devices ADRV9001 User Manual

UG-1828
Schematic Net Name
SPI_DO
MODE
RESET_TRX
DEV_MCS_FPGA_IN+
DEV_MCS_FPGA_IN-
DGPIO_0
DGPIO_1
DGPIO_2
DGPIO_3
DGPIO_4
DGPIO_5
DGPIO_6
DGPIO_7
DGPIO_8
DGPIO_9
DGPIO_10
DGPIO_11
GP_INT
VADJ_TEST_1 (VADJ_ERR)
VADJ_TEST_2 (PLATFORM_STATUS)
FPGA_MCS_IN+
FPGA_MCS_IN-

ISOLATION TECHNIQUES USED ON THE ADRV9001 EVALUATION CARD

Given the density of sensitive and critical signals, significant isolation challenges are faced when designing a PCB for the ADRV9001.
Isolation requirements listed below were followed to accurately evaluate the ADRV9001 device performance. Analytically determining
aggressor-to-victim isolation in a system is very complex and involves considering vector combinations of aggressor signals and coupling
mechanisms.
Isolation Goals
Table 96 lists the isolation targets for each RF channel-to-channel combination type. To meet these goals with significant margin,
isolation structures were designed into the ADRV9001 evaluation board.
Table 96. Port to Port Isolation Goals
Tx1 to Tx2
Tx1 to Rx1A/Rx1B
Tx1 to Rx2A/Rx2B
Rx1A/Rx1B to Rx2A/Rx2B
Rx1A to Rx1B
Isolation Between RF IO Ports
These are the primary coupling mechanisms between RF IO paths on the evaluation board:
Magnetic field coupling
•
Surface propagation
•
Cross domain coupling via ground
•
To reduce the impact of these coupling mechanisms on the ADRV9001 customer evaluation board, several strategies were used. Large
slots are opened in the ground plane between RF IO paths. These discontinuities prevent surface propagation. These structures consist of
a combination of slots and square apertures. Both structures are present on every copper layer of the PCB stack. The advantage of using
square apertures is that signals can be routed between the openings without disturbing the isolation benefits that the array of apertures
provides. A careful designer will notice various bends in the routing of differential paths. These routes were developed and tuned
FMC Connector Mappings
G16-FMC_LA12_N
D17-FMC_LA13_P
D18-FMC_LA13_N
C18-FMC_LA14_P
C19-FMC_LA14_N
G18-FMC_LA16_P
G19-FMC_LA16_N
H20-FMC_LA15_N
H17-FMC_LA11_N
D15-FMC_LA09_N
C15-FMC_LA10_N
C26-FMC_LA27_P
D26-FMC_LA26_P
H31-FMC_LA28_P
H32-FMC_LA28_N
H16-FMC_LA11_P
C27-FMC_LA27_N
H34-FMC_LA30_P
G33-FMC_LA31_P
G34-FMC_LA31_N
H37-FMC_LA32_P
H38-FMC_LA32_N
30 MHz to 1 GHz
75 dB
75 dB
75 dB
70 dB
70 dB
Rev. PrA | Page 222 of 253
Preliminary Technical Data
1 GHz to 6 GHz
70 dB
70 dB
70 dB
65 dB
65 dB