FAQ: ADL5802 Low Frequency Operation

Document created by MickOC Employee on Jul 11, 2011Last modified by AndyR on Jan 31, 2012
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Q.

The ADL5802 datasheet states that the device is capable of operation to  frequencies as low as 100 MHz, yet the Typical Performance  Characteristics plots only show data as low as 500 MHz. Is the device capable of operation at these low frequencies and is there any typical  performance data available?

 

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A.

The ADL5802 is indeed capable of operating at frequencies as low as 100 MHz and below. In order to achieve low frequency operation some changes are  necessary to the standard evaluation board. Specifically, the RF series input capacitors (C5, C12, C13 & C14) should be changed from their datasheet recommended value of 100pF to a higher value of 1nF. The lower capacitor values create a highpass filter effect  on the input resulting in poor return loss at low frequency which  should be avoided.

 

The  performance of the ADL5802 was characterized for IF frequencies of 10  MHz and 70 MHz in Low Side LO and High Side LO configurations. The  typical performance of the ADL5802 can be seen in the attached plots.

 

The  standard ADL5802 evaluation board configuration was used. Capacitors  C5, C12, C13 & C14 were replaced with 1nF capacitors. VS=5V, VSET=3.8V,  unless otherwise noted. The 4:1 IF port transformer (TC4-1W+), the RF and LO port transformers ( TC1-1-13M+) and PCB loss are included in the  measurement.

 

Summary: The ADL5802 under low frequencies indicates the following typical  performance: Gain = 0.6dB (Balun and PCB loss inclusive), IIP3 = 33dBm,  IIP2 = 70dBm, P1dB = 13dBm and Noise Figure = 11dB.

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