AD8318ACPZ-R2 datasheet(21/24 Pages) AD

21 / 24 page

AD8318

Rev. B | Page 21 of 24

CHARACTERIZATION SETUP AND METHODS

To measure noise spectral density, the 0 Ω resistor in series with

the VOUT pin is replaced with a 1 μF dc blocking capacitor.

The capacitor is used because the Rohde & Schwarz FSEA

spectrum analyzer cannot handle dc voltages at its RF input.

The CLPF pin is left open for data collected for Figure 19. For

Figure 20, a 1 μF capacitor is placed between CLPF and ground.

The large capacitor filters the noise from the detector stages

of the log amp. Noise spectral density measurements are taken

using the FSEA spectrum analyzer and the SMT06 signal

generator. The signal generator frequency is set to 2.2 GHz.

The spectrum analyzer has a span of 10 Hz, resolution

bandwidth of 50 Hz, video bandwidth of 50 Hz, and averages

the signal 100×. Data is adjusted to account for the dc blocking

capacitor impedance on the output at lower frequencies.

The general hardware configuration used for the AD8318

characterization is shown in Figure 47. The primary setup used

for characterization is measurement mode. The characterization

board is similar to the customer evaluation board with the

exception that the RF input has a Rosenberger SMA connector

and R10 has changed to a 1 kΩ resistor to remove cable

capacitance from the bench characterization setup. Slope and

intercept are calculated in this data sheet and in the production

environment using linear regression from −50 dBm to −10 dBm.

The slope and intercept generate an ideal line. Log conformance

error is the difference from the ideal line and the measured

output voltage for a given temperature in dB. For additional

information on the error calculation, refer to the Device

Calibration and Error Calculation section.

The hardware configuration for pulse response measurement

replaces the 0 Ω series resistor at the VOUT pin with a 40 Ω

resistor; the CLPF pin remains open. Pulse response time is

measured using a Tektronix TDS5104 digital phosphor

oscilloscope. Both channels on the scope are configured for

50 Ω termination. The 10 Ω internal series resistance at VOUT,

combined with the 40 Ω resistor, attenuates the output voltage

level by two. RF input frequency is set to 100 MHz with

−10 dBm at the input of the device. The RF burst is generated

using a Rohde & Schwarz SMT06 with the pulse option with a

period of 1.5 μs, a width of 0.1 μs, and a pulse delay of 0.04 μs.

The output response is triggered using the video output from

the SMT06. Refer to Figure 47 for an overview of the test setup.

VIDEO

OUT

RF OUT

–7dBm

ROHDE & SCHWARZ

SMT06

TEKTRONIX

TDS5104

CH1* CH3* TRIGGER

VOUT

GND

AD8318

VPOS

VSET

INHI

INLO

40Ω

52.3Ω

1nF

*50Ω

TERMINATION

3dB

SPLITTER

Figure 47. Pulse Response Measurement Test Setup

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