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ADL5391 Rev. 0 | Page 12 of 16 0 –65 –60 –55 –50 –45 –40 –35 –30 –25 –20 –15 –10 –5 10 100 200 300 400 500 600 700 800 900 1000 FREQUENCY (MHz) BLEEDTHRU GAIN SECOND HARMONIC GAIN THIRD HARMONIC GAIN Figure 18. Single-Ended (DC) ADL5391 Used as a Harmonic Generator 21Ω 74Ω 21Ω 74Ω XIN YIN 150Ω 62Ω 5dB PAD 5dB PAD 10dB PAD 53Ω 53Ω 200Ω XM XP YM YP WP WM Figure 19. Setup for Single-Ended Data Use as a Detector The ADL5391 can be used as a square law detector. When amplitude squaring is performed, there are components of the multiplier output that correlate to the signal bleedthrough and second harmonic, as seen in Equation 4. However, as noted in the Squaring and Frequency Doubling section, there is also a dc component that is directly related to the offset and the squared input magnitude. If a signal is split and feed into the X and Y inputs and a low-pass filter were place on the output, the resulting dc signal would be directly related to the square of the input magnitude. The intercept of the response will shift slightly from part to part (and over temperature) with the offset, but this can be removed through calibration. Figure 20 shows the response of the ADL5391 as a square law detector, Figure 21 shows the error vs. the input power, and Figure 22 shows the configuration used. 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 00 0.7 0.6 0.5 0.4 0.3 0.2 0.1 VIN (V rms)2 .8 Figure 20. ADL5391 Used as Square Law Detector DC Output vs. Square of Input 1.6 –0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 –30 10 5 0 –5 –10 –15 –20 –25 PIN X (dBm) Figure 21. ADL5391Used as a Square Law Detector Error vs. Power Input T1 45nF 40µH 40µH 74µH 74µH J2 WM J1 WP XM XP YM YP 11 12 13 14 WP WM 6 5 R2 56.2Ω TC1-1-13M T3 C7 0.1µF C18 0.1µF J6 YP R1 56.2Ω TC1-1-13M T2 C4 0.1µF C20 0.1µF J8 XP R4 100Ω R12 OPEN 40nF R6 24.9Ω R5 24.9Ω Figure 22. Schematic for ADL5391 Used as Square Law Detector |
