AD8369 datasheet(20/24 Pages) AD

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AD8369

APPENDIX

Characterization Equipment

Two sets of automated characterization equipment were used to

obtain the majority of the information contained in this data sheet.

An Agilent N4441A Balanced Measurement System was used to

obtain the gain, phase, group delay, reverse isolation, CMRR,

and s-parameter information. Except for the s-parameter informa-

tion, T-attenuator pads were used to match the 50

W impedance of

the ports of this instrument to the AD8369.

An Anritsu MS4623B “Scorpion” Vector Network Analyzer was

used to obtain nonlinear measurements IMD3, IP3, and P1dB

through matching baluns and attenuator networks.

Definitions of Selected Parameters

Common-mode rejection ratio (TPC 14) has been defined for

this characterization effort as:

Differential Mode forwardgain

Common Mode forwardgain

where the numerator is the gain into a differential load at the

output due to a differential source at the input and the denomina-

tor is the gain into a common-mode load at the output due to a

common-mode source at the input. In terms of mixed-mode

s-parameters, this equates to:

SDD

SCC

Reverse isolation (TPC 17) is defined as SDD12.

More information on mixed-mode s-parameters can be obtained

in the a reference by Bockelman, D.E. and Eisenstadt, W.R.,

Combined Differential and Common-Mode Scattering Parameters:

Theory and Simulation. IEEE Transactions on Microwave Theory

and Techniques, v 43, n 7, 1530 (July 1995).

Composite Waveform Assumption

The nonlinear two-tone measurements made for this data sheet,

i.e., IMD3 and IP3, are based on the assumption of a fixed value

composite waveform at the output, generally 1 V p-p. The fre-

quencies of interest dictate the use of RF test equipment and

because this equipment is generally not designed to work in

units of volts, but rather watts and dBm, an assumption was

made to simplify equipment setup and operation.

Two sinusoidal tones can be represented as:

Vf t

()

sin

Vf t

()

sin

The average voltage of one tone is:

Vdt

() =

where T is the period of the waveform. The average voltage of the

two-tone composite signal is:

VVdt

() =

So each tone contributes 1/

÷2 to the average composite ampli-

tude in terms of voltage. It can be shown that the average

power of this composite waveform is two times greater, or 3dB,

than that of the single tone. This principle can be used to set

correct input amplitudes from generators scaled in dBm and

is correct if the two tones are of equal amplitude and are not

farther than 1 percent apart in frequency.

10nF

CONTROL INTERFACE

PWUP VPOS SENB

FILT CMDC OPHI

INHI COMM

INLO

DENB

COMM BIT0

BIT1

BIT2

BIT3

AD8369

OPLO

0.1 F

PORT1

PORT2

PORT3

PORT4

AGILENT N4441A

(ALL PORTS 50 )

10nF

69.8

10nF

0.1 F

1nF

RL= 200 DIFFERENTIAL: R1 = 69.8 , R2 = 69.8

RL= 1000 DIFFERENTIAL: R1 = 475 , R2 = 52.3

Figure 12. Balanced Measurement System Setup

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