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On the SiLabs forum a support engineer explicitly states the best solution to low crosstalk is using multiple SI5351. That is what I intend to do

During testing I found some impact of output loading on the crosstalk between two active outputs. But unused outputs can be set to active low and the ppl shut down and changing loading of these muted

Speaking as a digital guy, the si5351 drivers seem to be CMOS digital type output buffers, so totem-pole 0v (low) and 3.3v (high) voltage sources with a programmable maximum current allowed? of 2ma,

Add to that -- termination at the operating impedance level will mean (if it's 50 ohm out) a 50 ohm resistor across the driven and return lines of each output, which naturally shunts all output to

Programming the chip to drive an unused output low, and then externally shorting that pin to ground, will effectively give that chip a second ground.? A very good thing, since the si5351 only has one

Could not find such a library for the SAMD21 architecture of the Due? and Zero, or at least Google could not find one. Anyone any idea where to find something? I know its possible to make one using

@Jerry Vaughn <jvaughn@...> My experience with documenting digital and mixed-signal ICs since the mid-1990s tells me that "good enough" rarely is. We've always used water as an analogy for

Forgot to mention. The tested SI5351A uses a 25MHz XCO as reference, hence the multiples of 5MHz, will be different if you use a 27MHz XCO The examples use output 0 for LO1 and output 2 for LO2 and

After more testing some rules: Target output is: The output required to have minimum spurs All dB levels in the rules refer to the target output level as 0dB - Muting an output and stopping the clock

The si5351 can be programmed to drive unused outputs low. That should be good enough.

Erik, Are the unused outputs physically terminated, or floating -- i.e. open? What you typed was -- they're not physically terminated, nor pulled either high or low, just programmed to "off." My

You're digging pretty deep here!?? Good stuff. I've never looked closely at spurs and phase noise out of an si5351, but did write the (very compact) routines for the uBitx, can give 3 arbitrary <=

Jim, The control lines are all terminated according to the data sheet. Different output terminations (open/short/capacitive/50 ohm) have been tested and have maximum 5dB impact on the levels of the

Hi I hope this may not be a spurious comment, but -- Have you tied the unused outputs and inputs (programming lines) ALL either high or low, per the mfg. datasheet? All digital ICs are notorious for

My home build VNA uses a single SI5351 to generate both the test signal and the LO for the downmix to the audio IF where the I/Q demodulation is done. The VNA has some problems in isolation and one

Tested with 1st IF at 500MHz? and I get 15dB less sensitivity. Compared 110MHz IF filter and 500MHz IF filter on my VNA and they have about the same loss. AD831 are 50 ohm matched on both RF input

I did a bit more testing, configuration now is: Low pass filter AD831 mixer with first LO as ADF4351 (directly connected, no need for low pass filter as the AD831 makes it a square wave anyway) 10dB

Erik, Thank you for the post. I also have a couple of the AD831 modules and want to try them for the SA project. How exactly are you connecting the LO to AD831's? If putting a LPF on the signal input

I assume that's an ADF4351. Jerry

Mixers tend to mix everything available, not just the stuff you expect. And with some mixers at least, the unwanted (and wanted) products can get reflected back in to make another set of