Latest Comments Kitty on Musiland Devices: You are commenting using your Facebook account. I have heard that operation below the specified 10MHz lower limit is possible too but have not confirmed this myself. What SiLabs claims to be inside and what really is inside NO decoupling cap: It has 8 pins, and although a small surface mount package, you can still solder it reasonably easily, even with no PCB. Given how low the Si jitter is in fractional mode, they probably do a pretty good job on duty cycle as well. I likes those analysis as found useful for my RF designs.

Pressing the knob will move the “cursor” to the next right digit. In order to have a student proof, lab suiteable device, we addded a measurement amplifier and a case. Programming interface The DDS chips have a serial programming interface, and programming is easy. Even comparing the original factory spec values for the Si vs the CCHD, the Si is not that much higher in terms of jitter 1. Listening in with a nearby Bitx40 I hear no hint of a tick. Bear in mind though that you need an anti-alias low pass filter on the output of DDS chips to produce a clean output. The Si is based on a PLL technology, which generally has a much higher phase noise.

I do wonder though if any of these plof for lowering overall noise really helps us down at Hz where we need it the most. Bear in mind that every application is different! From the waveforms below, we see that setting the timer interrupt to 1 ms should be far more than necessary to detect the slopes.

Inside the Silicon Labs Si Programmable XO | H i F i D U I N O

Email Address never made public. DAC’s typically go from bits in some earlier devices up to bits in a top-of-the-range device like the AD As you can see and already know, the phase noise performance is definitely worse than the Si 2.

In others, you are faced with the usual decisions about trade-offs. Phaase of the new topic: Then put delays in the I2C write – so that each step takes 5ms. The important thing for me is it sounds clean on the SW receiver, even when going through a transition between one integer and the next. Programming interface The DDS chips have a serial programming interface, and programming is easy.


You can make it as accurate and stable as you like. Using switched mixers it makes sense to use a rectangular oscillator signal. However, I’d say that for many applications the Si phase noise performance would be sufficient, and probably better than many expensive commercial “black box” amateur radio transceivers on the market. This cannot be undone.

Not so, the DDS! Do you have a test showing both? Yes, mentioned jitter for Si is specified when it is used as oscillator with attached quartz. Thats my reading of it anyway. This is not the same as the actual phase noise you would observe on the output – for that you need to also add the phase noise of the reference oscillator – so it is not directly comparable with the phase noise of an Si I think Ian has been very careful with his comments and comparisons to other clocks, as ashamedly he may open himself up for ridicule, gotta love the forum….

Some DDS chips have an onboard oscillator where you can just connect the crystal directly to the chip. The DDS chips have a serial programming interface, and programming is easy.

USB Controlled Synthesizer

Notify me of new comments via email. For output frequencies in the MHz HF range, the spurs are very minimal. Many of the DDS chips have an onboard comparator which can easily be used to turn the sinewave output into a squarewave, if that’s what you need. Just like a favourite colour, or a favourite lucky number, I don’t need a good reason. The Si is a digital phase locked loop oscillator producing a squarewave output.

This integrated circuit is widespread and does it’s job in various DIY Applications. Above images taken from here: I have not found phase noise to be a problem. This luxury of easy soldering and easy “programming” ssi570 it’s price. The input values are assumed to be in Ploy adecimal format. You never could get free Si samples from SiLabs.


It would be very interesting to see what happens then! Waveform when turning “moderate” here the horiz. Occurred to me but I hoise gotten around to it. I am using my code noiee his ideas. The lid is glued so tight and the ceramic case would first break.

The board design needs lots of care too, with all that high frequency stuff rolling around. On Fr, Jun 30, at Control the amplitude, control the phase, add spur killing.

Timing Forum

The contrast may be set in software or by the potentiometer on the shield. Offset f — Phase Noise 10 Wi570 noise data with Si data from datasheet, the Crystek and the Crystek from their respective data sheet: Phase noise Phase noise can be imagined as a widening of the theoretical perfect vertical line you would see on a spectrum analyser examining the output signal.

TPS7A is a good choice. Jerry, KE7ER toggle quoted message. If you want a sinewave, you’ll need a lot of low pass filtering to get rid of the rich suite of harmonics. So likely sometimes an extra ms in there. When the manufacturer first introduced the device, it provided the following jitter phase plot [ link ].

His article is available from http: In receive applications, spurs will show up as birdies in the receiver, and are more serious. Then you need the reconstruction filter typically low pass at the output, and that needs to be carefully designed too.

For a high performance receiver, it is really important to use a low phase noise local phwse. Let’s get serial UT Am curious exactly how you are using that 1pps GPS to guide the raduino. AD giving you tuning resolution down to steps of a few micro-Hz, if you should ever need it!