X3C07P1-04S Datasheet, PDF (18/19 Pages) Anaren Microwave – Production Friendly

Model X3C07P1-04S
Rev A
Application Information
The X3C07P1-04S is an “X” style 4dB coupler. Port configurations are defined in the table on page 2 of this data sheet
and an example driving port 1 is shown below. The change was made to allow better placement of the termination
resistors when the coupler is used in a serial splitter/combiner network.
Ideal Coupler Operation
1V
1
4
0.631V  (-4dB)
Isolated port 2
3
0.776V  (-2.2dB)
The primary application for 4dB couplers is in serial splitting and combining networks. These networks are often
employed when the combining of 3 amplifiers is required. Unlike corporate networks, serial networks are not limited to
binary divisions (corporate networks are limited to 2 ⁿ number of splits, where n is an integer). Serial networks can be
designed with [3, 4, 5, …, n] splits, but have a practical limitation of about 8 splits.
2-Way Splitter for Doherty Power Amplifer
Main
°
Amplifier
°
Input
3dB/4dB/5dB
Hybrid Coupler
°
Peaking
Amplifier
°
35 90°
Output
Hybrid coupler can be used in Doherty power amplifier to split the input power into the desired power ratio and phase
delay. In above symmetrical Doherty power amplifier (main and peaking amplifier delivers equal amount output power at
max drive condition), 3dB hybrid splits the input power into 1:1 ratio with 90 degree phase difference.
When the peaking amplifier is off, or when peaking amplifier is dramatically different than main amplifier due to bias,
matching, difference between transistors, the 3dB hybrid coupler does not see equally unmatched termination, the
mismatch is then reflected not only to isolated port, but also shows up at input port as return loss mismatch.
4dB hybrid splits the input power into 1:15 ratio with 90 degree phase difference. It can be used in asymmetrical (1:1.5)
Doherty power amplifier architecture as splitter. The 4dB hybrid is also used in some symmetrical Doherty power
amplifier to compensate the gain difference between main and peaking amplifiers. It is worth noting that 3dB and 4dB
hybrid react differently to the termination mismatch, resulting in different return loss at input port.
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