ADL6337ACRZB-R7 datasheet(19/41 Pages) AD

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Data Sheet

ADL6337

THEORY OF OPERATION

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Rev. B | 19 of 41

A typical RF transmitter transmits RF power at a fixed output level.

System gain varies over time, temperature, and process. Therefore,

a gain adjustable block is needed to calibrate and compensate this

variation. A VGA provides this programmable gain function.

The ADL6337 is a highly integrated RF VGA solution for transmit

paths. It provides a single-chip solution that contains a balun for

differential to single-ended signal conversion, digital attenuation,

and gain stages while offering high dynamic range multicarrier

transmitter designs.

The ADL6337 is a highly integrated 2-stage VGA used to interface

an RF DAC to the power amplifier in the transmitter. It offers

multiple gain control options with a 31.5 dB attenuation range in 0.5

dB steps integrating a RF Digital Step Attenuator (DSA1), a high

linearity amplifier, followed by a second RF Digital Step Attenuator

(DSA2), and a second high linearity amplifier.

Putting together the ADL6337 building blocks, the signal path

through the device starts with converting the differential inputs to

single ended by the integrated balun at the output.

The integrated building blocks of the ADL6337 are programmable

via the SPI.

RF INPUT AND OUTPUT

The input impedance is 50 Ω differential and the output impedance

is 50 Ω single-ended to allow the device to be driven by the

DAC . 100 Ω differential inputs can be also achieved with external

matching networks. See the Input Port Matching section.

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