AD9361 Reference Manual UG-570
| Page 61 of 128
RF PORT INTERFACE
OVERVIEW
The purpose of this section is to define the expected AD9361
port impedance values and potential impedance matching
techniques.
The AD9361 has with two independent receive paths and two
independent transmit paths. Each receive path has three (A, B,
and C) LNA inputs and each transmit path has two (A and B)
Tx outputs. The LNA inputs and Tx outputs require external
impedance matching networks. The receiver LNA input ports
may be utilized in either a single-ended mode or differential
mode. The transmitter output ports may only be utilized in a
differential mode.
It is critical to have these interfaces working properly to achieve
data sheet performance levels. The main considerations are as
follows:
• Rx interface type: single ended or differential?
• Device to be interfaced: such as, filter, balun, T/R switch,
external LNA, external PA: Short to ground at DC?
• Rx LNA maximum (no damage) input power ( +2.5 dBm
Peak: single-ended: lossless match: 50 Ω source).
• Rx LNA input port DC voltage level (~ +0.6 V
DC
).
• Tx output port bias (+1.3 V
DC
@ 75 mA per side @
maximum output power).
• Board design: such as reference-planes, transmission lines,
impedance matching.
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