Data Sheet

AD8318

USING THE AD8318

analog.com

Rev. E | 21 of 24

input has a Rosenberger SMA connector and R10 has changed to

a 1 kΩ resistor to remove cable capacitance from the bench char-

acterization 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 repla-

ces 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.

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.

Figure 47. Pulse Response Measurement Test Setup