ADRF6510ACPZ-R7 datasheet(20/32 Pages) AD

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ADRF6510

Data Sheet

Rev. B | Page 20 of 32

APPLICATIONS INFORMATION

BASIC CONNECTIONS

Figure 49 shows the basic connections for operating the

ADRF6510. A voltage from 4.75 V to 5.25 V should be applied

to the supply pins. Each supply pin should be decoupled with at

least one low inductance, surface-mount ceramic capacitor of

0.1 µF placed as close as possible to the device.

The input buffers provide an interface to the sensitive filter

sections that follow. They set a differential input impedance

of 400 Ω and sit at a nominal common-mode voltage of VPS/2.

The inputs can be dc-coupled or ac-coupled. If using direct

dc-coupling, the common-mode voltage, VCM, can range from

1.5 V to 3 V.

The output buffers of the ADRF6510 are low impedance

(~20 Ω) designed to drive either ADC inputs or subsequent

amplifier stages. The output common-mode voltage defaults to

VPS/2 but can be adjusted from 1.5 V to 3.0 V without loss of

drive capability by presenting the VOCM pin with the desired

common-mode voltage. The high input impedance of VOCM

allows the ADC reference output to be connected directly.

To enable the ADRF6510, the ENBL pin must be pulled high.

Taking ENBL low disables the device, reducing current con-

sumption to approximately 2 mA at ambient temperature.

ERROR VECTOR MAGNITUDE (EVM) PERFORMANCE

Error vector magnitude (EVM) is a measure used to quantify

the performance of a digital radio transmitter or receiver by

measuring the fidelity of the digital signal transmitted or

received. Various imperfections in the link, such as magnitude

and phase imbalance, noise, and distortion, cause the constel-

lation points to deviate from their ideal locations.

In general, a receiver exhibits three distinct EVM limitations

vs. received input signal power. As signal power increases, the

distortion components increase.

•

At large enough signal levels, where the distortion compo-

nents due to the harmonic nonlinearities in the device

dominate, EVM degrades as signal levels increase.

•

At medium signal levels, where the signal chain behaves

in a linear manner and the signal is well above any notable

noise contributions, EVM has a tendency to reach an

optimal level determined dominantly by either the

quadrature accuracy and I/Q gain match of the signal

chain or the precision of the test equipment.

•

As signal levels decrease, such that noise is a major con-

tributor, EVM performance vs. the signal level exhibits

a decibel-for-decibel degradation with decreasing signal

levels. At these lower signal levels, where noise is the

dominant limitation, decibel EVM is directly proportional

to the SNR.

VPSD

COMD

CLK

DATA

SDO

COM

VPS

OPP1

OPM1

COM

GAIN

VOCM

COM

OPM2

OPP2

COM

INP2

INM2

VPS

COM

OFDS

OFS2

VPS

ENBL

INP1

INM1

VPS

COM

GNSW

OFS1

VPS

ADRF6510

VPSD

CLK

DATA

SDO

INP2

INM2

VPS

OPP2

INM1

INP1

OPM1

OPM2

OPP1

VPS

Figure 49. Basic Connections

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