Data Sheet

ADTR1107

INTERFACING THE ADTR1107 TO THE ADAR1000 X BAND AND KU BAND BEAMFORMER

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Rev. C | 26 of 27

The ADTR1107 can be interfaced to the ADAR1000 X band and Ku

band quad beamformer IC, as shown in Figure 91. Note that only

a single channel of the ADAR1000 is shown in Figure 91 and addi-

tional components have been omitted for clarity. The ADAR1000

provides multiple bias voltages and control signals, resulting in a

glueless interface and no need for any additional control signals to

the ADTR1107. The gate voltage for the ADTR1107 power amplifier

(VGG_PA) is provided by the ADAR1000 PA_BIAS3 pin. One of

four independent negative gate voltages is needed for power ampli-

fier gate biasing. Each voltage is set by an 8-bit digital-to-analog

converter (DAC) with an output voltage range of 0 V to −4.8 V.

The typical gate voltage required to bias the ADTR1107 power

amplifier is −1.1 V (see Figure 49). This voltage can be asserted

by the ADAR1000 TR input pin (rising edge enables the power

amplifier) or by a serial peripheral interface (SPI) write. Asserting

the ADAR1000 TR pin switches the polarity of the ADAR1000

TR_SW_NEG pin and TR_SW_POS pin. The TR_SW_POS pin

can drive the gates of up to four switches and can be used to

control the ADTR1107 SPDT switch.

While the ADTR1107 LNA gate voltage is self biased (the

VGG_LNA pin is connected to 0 V or grounded), the voltage can

also be controlled from the ADAR1000. In this case, there is a

single LNA_BIAS voltage (0 V to −4.8 V) controlled by an 8‑bit DAC

that can be used to bias four ADTR1107 devices connected to each

ADAR1000.

The ADTR1107 CPLR_OUT coupler output can be tied back to one

of the four ADAR1000 RF detector inputs (DET1 to DET4). These

diode based RF detectors have an input range of −20 dBm to

+10 dBm. The coupling factor of the ADTR1107 directional coupler

ranges from 28 dB at 6 GHz to 18 dB at 18 GHz. At 12 GHz,

with a coupling factor of 22 dB and a maximum power amplifier

output of 26 dBm, the coupled output power is a maximum of 4

dBm. If the coupler output is connected directly to the detector

input, this connection provides a detection range of 24 dB. Figure

90 shows the relationship between the ADTR1107 output power

and the ADC code of the ADAR1000 detector at 12 GHz. In this

case, the ADTR1107 output power is swept to a maximum level of

approximately 22 dBm.

Figure 90. ADAR1000 RF Detector Output Code vs. ADTR1107 Output Power

at 12 GHz

Figure 91. Interfacing the ADTR1107 to the ADAR1000 X and Ku Band Beamformer, One Channel Shown