ADTR1107ACCZ-R7 datasheet(26/28 Pages) AD

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ADTR1107

Data Sheet

Rev. A | Page 26 of 28

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

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 additional 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 amplifier 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.

100

0.1

523

ADTR1107 OUTPUT POWER (dBm)

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

at 12 GHz

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