CN-0171

Circuit Note

Rev. 0 | Page 2 of 3

The single-tone performance for an input frequency of 170 MHz

and a sampling rate of 122.88 MSPS is shown in Figure 3. Two-

tone performance is shown in Figure 4.

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FREQUENCY (MHz)

Figure 2. Normalized Frequency Response of the ADC Interface

Shown in Figure 1

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FREQUENCY (MHz)

SAMPLE FREQUENCY = 122.88MHz

SNRFS = 75.877dB

INPUT FREQUENCY = 170MHZ

FUNDAMENTAL POWER = –1.044dBFS

SECOND HARMONIC POWER = –75.499dBc

THIRD HARMONIC POWER = –80.003dBc

NOISE

√Hz = –153.762dBFS/√Hz

Figure 3. Measured Single-Tone Performance of the Circuit Shown

in Figure 1 for an Input Frequency of 17 0MHz and Sampling Frequency

of 122.88 MSPS

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FREQUENCY (MHz)

FUNDAMENTAL1 = –7.161dBFS

FUNDAMENTAL2 = –7.116dBFS

IMD (2f1 – f2) = –66.07dBc

IMD (2f2 – f1) = –67.588dBc

NOISE FLOOR = –150.84dBFS/

√Hz

Figure 4. Measured Two-Tone Performance of the Circuit Shown

in Figure 1 for Input Tones Centered at 170 MHz and a Sampling Rate

of 122.88 MSPS

COMMON VARIATIONS

The application circuit described here can be modified for any

IF frequency within the operating range of the ADL5535/ADL5536

and the AD9268. As an alternative to the AD9268, the AD9640,

the AD6657, or the AD9644 can be used for the ADC in this

application.