Data Sheet

ADL5330

Rev. B | Page 17 of 24

Figure 40 shows the response of the AGC RF output to a pulse

on VSET. As VSET decreases to 1 V, the AGC loop responds

with an RF burst. Response time and the amount of signal

pin—a function analogous to the feedback capacitor around an

integrating amplifier. An increase in the capacitance results in

slower response time.



M10.0

s

A CH1

2.60V

2

1

T

20.2000

s

T

ADL5330 OUTPUT

T

Figure 40. Oscilloscope Screenshot Showing the

Response Time of the AGC Loop

More information on the use of AD8318 in an AGC application

can be found in the AD8318 data sheet.

INTERFACING TO AN IQ MODULATOR

The basic connections for interfacing the AD8349 with the

ADL5330 are shown in Figure 42. The AD8349 is an RF

quadrature modulator with an output frequency range of

700 MHz to 2.7 GHz. It offers excellent phase accuracy and

amplitude balance, enabling high performance direct RF

modulation for communication systems.

The output of the AD8349 is designed to drive 50 Ω loads and

easily interfaces with the ADL5330. The input to the ADL5330

can be driven single-ended, as shown in Figure 42. Similar con-

figurations are possible with the AD8345 (250 MHz to 1 GHz)

and AD8346 (800 MHz to 2.5 GHz) quadrature modulators.

Figure 41 shows how output power, EVM, ACPR, and noise

1.4 V. Figure 41 shows that the modulation generated by the

AD8349 is a 1 GHz 64 QAM waveform with a 1 MHz symbol

rate. The ACPR values are measured in 1 MHz bandwidths at

1.1 MHz and 2.2 MHz carrier offsets. Noise floor is measured at

a 20 MHz carrier offset.

1.4

0

0.2

0.4

0.8

0.6

1.0

1.2

20

4.5

0

4.0

–20

3.5

–40

3.0

–60

2.5

–80

2.0

–100

1.5

–120

1.0

–140

0.5

–160

0

EVM

OUTPUT POWER

ACPR 2.2MHz OFFSET

ACPR 1.1MHz OFFSET

NOISE FLOOR

Figure 41. AD8349 and ADL5330 Output Power, ACPR, EVM, and Noise vs.

The output of the AD8349 driving the ADL5330 should be

limited to the range that provides the optimal EVM and ACPR

performance. The power range is found by sweeping the output

power of the AD8349 to find the best compromise between

EVM and ACPR of the system. In Figure 41, the AD8349 output

power is set to −15 dBm.

100pF

100pF

INHI

INLO

RF OUTPUT

100pF

100pF

OPHI

COMM

VPOS

OPLO

ADL5330

RF VGA

120nH

120nH

+5V

+5V

ETC1-1-13

LO

100pF

100pF

200



200



ETC1-1-13

IBBP

IBBN

QBBP

QBBN

COMM

VPOS

AD8349

IQ MOD

+5V

GAIN CONTROL

DAC

DAC

DIFFERENTIAL I/Q

BASEBAND INPUTS

Figure 42. AD8349 Quadrature Modulator and ADL5330 Interface