Si4133D PLL Calculator

[VK4GHZ]

This an Excel spreadsheet calculator, for calculating the HEX values in order to program a PLL Synthesizer using an Si4133D.
It is based on the good work of David, VK3HZ, with a few extra things here and there.

Note, this is for the "D" variant of the 4133, not the "G" variant that comes standard with a VK3XDK PLL board.

What's the difference?
With the "D" you can program the "R Divider".



Above: Screen shot at 75% real size

You enter the reference frequency, usually 10MHz, phase detector frequency (PLL stepping frequency), and your desired output.
It will calculate the 3 bytes required for the N Divider, and 3 bytes for the R Divider.
Also, it will even create a line of code you can copy and paste straight into the PICAXE Programming Editor.

The xls file is attached below for you to download and try out.

[VK5ZD]

Hi

Re the VCO limits, I doubt if the IF VCO will go that low directly. You need to use the IF divider [set to 8] to get the lower limit of 62.5MHz quoted in the datasheet.

Iain

[VK4ADC]

Guys

There is also a stand-alone exe-file (mainly for Windows-32) available on my web site under the "Using the Si4133 RF Synthesiser Chip", dated June 2011. No need for Excel and does the same thing. You will find the link about 2/3 of the way down the page just under the screen image. Page link : http://www.vk4adc.com/content/index.php ... &Itemid=43

I have been using it for my various implementations of the "D" suffixed chip and it provides the goods every time.

[VK4GHZ]

Re the VCO limits, I doubt if the IF VCO will go that low directly.

It's as per the "D" datasheet.

The D variant has a significantly wider IF output range (62.5 - 1000 MHz), compared to the [familiar] G variant (500 - 1000 MHz).
Yes, there is an IF divider which can be set to 8, but also 4, 2, and 1.

Of course, neither of these will work over the entire range with any one value of inductor.

[VK5ZD]

Hi

It's as per the "D" datasheet.

Check the IF VCO Centre Frequency Range

73
Iain

[VK4GHZ]

The Si4133 is a curious device.

The lock range of the IF's VCO on one of my boards is around 412 - 562 MHz.
It goes down much lower than the 500 MHz (526 - 5%) data sheet specification.
Another one of my boards covered 480- 640 MHz.
Perhaps a suitable default lower IF VCO value for the XLS would be 400.

Playing with this a bit further, aiming for an IF output of 206 MHz to see what happens with the IF divider, and the following was observed.


Above: IF synthesizer set to 412 MHz, and IF divider set to 2

If you're expecting just to see 206 MHz, you'll be disappointed!
Rich in harmonics.
A low pass filter is definitely required, if you intend to divide down to a lower frequency.
The desired output at 206 MHz is the strongest signal, but the second, third and fourth harmonics are less than -30db down.

For the exercise, I also generated 62.5 MHz (set to 500 MHz with divide by 8 ), and that had harmonics of 62.5 all the way up to 500 MHz.