yig pll
Did anyone have a document or any information about the YIG Based Synthesizer.
Thanks in advance,
Ballimo
whatcha wanna know?
I'am designing a YIG based synthesizer,did you have a reference PLL design using a YIG Oscillator? I assume that a Voltage to current converter (=YIG driver) have to be placed before the YIG oscillators and I have this circuit; what I want to know is the difference between PLL circuit design using YIG and PLL circuit using a VCO. do you have any document about that?
Thanks,
Ballimo
The main difference is that YIG oscillators are tuned via a large current in a big magnetic coil. VCO's are tuned with a tuning voltage (almost no current).
Depending on your application, this might make no difference at all, or it might mean a great deal.
You usually make some sort of YIG coil driver, that linearly converts voltage to current. Then you put a standard PLL in front of that.
Where you get into trouble is that you are still driving a big magnetic coil. That coil has inductance, which means there will be a "lowpass" pole in the dynamic tuning curve. As you may be aware, PLL's do not like low frequency additional poles in the control loop filter design. You may have to add a control loop zero, or more fancy phase compensation (lead-lag) network in the PLL to compensate for the tuning coil pole. Otherwise you might have ringing, or even control loop instability.
You also need to inject a DC current into the coil to get the oscillator "centered" in the desired frequency band, so the coil driver has to be able to provide this. Sometimes, you can buy a YIG oscillator with a permanent magnet in it to accomplish the same thing without wasting DC current (but watch out for tuning hysteresis).
I have seen some synthesizers use YIGs with two tuning coils. A DAC drives the coarse tuning coil to get you close to the desired frequency, and the PLL drives a (lower inductance) fine tuning coil. This allows faster lock-up time, and wider control loop bandwidths.
Rich
thank you Rich for you help,
The YIG oscillators I am planing to use have a Main coil with a sensitivity of 14 MHz/mA and an FM coil with a 310 KHz/mA for fine freq adjustment.
I think that it is better to use a DAC to drives the coarse tuning coil to get close to the desired frequency, and PLL drives the FM coil with a low inductance this will eliminate the "trouble" driving a big magnetic coil, as you said.
Regards,
Ballimo
Off topic: I think the key to career development, if you are a microwave engineer, is to stay connected to the technical side of things. I have managed a lot of engineers and teams, and I try to keep technically involved in every design. It might be reviewing designs, it might be to carve out a little chunk of the system to design yourself. And I recommend to NOT specialize in one small technology! Lets say you are designing RF receivers and transmitters--you really want to try to learn a lot about the ADC/DAC, DSP processor, coding algorithms, etc. too. That way, when the entire system ends up on a chip, you are still employable! Technology changes very quickly, and the area you thought was going to dominate can disappear overnight. If you keep a technical foot in things, then you have a lot more job portability. Also, if you someday become a consultant, you can provide useful information to a very wide range of clients.
Another help is to keep an open mind, and attend papers, talks, trade shows, evening classes, etc. You never know when you might need that info to solve a problem. Teaching classes is another good way to grow--try teaching a class on microwave testing to your company's technicians, for example. You really do not know something until you are able to teach it to somebody else.
Anyone going to the IMS 2009 show in Boston? That is a great way to pick up on where the industry is going, new design tricks, etc. Just walking around the vendor booths and looking at open units is worth the price of admission!
Hi dear
i'm loking for a some information about yig WJ 572-59 2,16 ghz 4,16 ghz, supply volts and voltage tuning on pin connection haven't datashet anyone halp me !
thank you
look at Avantech and maybe omniyig...they may have a similar model with the same pinout.
There is going to be one pair of pins that is the coarse tune...you can find it with an ohmmeter. Then a 2nd set of pins that is fine tune...some ohm meter, but look for a higher resistance. The ground is connected to metal case, so easy to find. A lot of them have 24V DC heater circuits on two pins, floating from any ground connection.
Good luck