This chip I hope will be good news in time..... I set up a LTSpice file model to test the split in two, MC1496 for quadrature I/Q output. Which was demonstrated could to be possible in a previous test file of the idea here in the group files. Since I have changed the circuits operation it wants to operate in a linear region of 360mV p~p into a 50K output. There are some losses but the sound card will make up for that. This seems to me to a nice peak output level. I hope it will please people. Wild voltage swings and all do not serve the new modified way of using this chip. Since I internally switch off two transistors to divide the chip in halves. So its output impedance is now something new. You know, higher.
I continued to work around the two 50 ohm inputs of the circuit. So that might interest some folk who like to use allot of 50 ohm broadband HF preamps. I am thinking, from my test so far, that the software acts like the input is in the 1K region. So I have 50 ohms matched up to about 1k at this point. The best way to find out exactly what the input impedance will be is to test the circuit on the bench. But we know the range now. As I said the circuit has been changed from its normal use to something different in view. Its input behavior has to be redefined. I will do some of the software plot math here later to see if I can calculate the input impedance on the pins. Get us an good idea. You can unmistakably see the 90 degrees between the output waveforms and calculate it from the software plot data. There is a big angular rotation of the input through the circuit to the output end. So unless you use your math for rotation around 360 degrees, or more, back around again, you might be mistaken about the 90 degree phase angle relationship in the end. Being it has rotated allot relative to the input reference. I and Q will still have a difference of 90 degrees as the smaller angle between them. Sometimes the software shows you the larger angle between them after they have rotated around some. The larger angle adds up to 270 degrees. I also set up a mixer test. Where I took the above circuit and added a signal input that I can vary from 1 MHz to 10 MHz to watch the mixing effect in the I/Q waveform outputs. What you can not see in the waveforms is such a thing as a small offset of 12 kHz, so you have to examine the mixer with wider frequency offsets of several MHz to demonstrate the effect and see the mixing levels. Anyways it will act as a mixer in its upper section. You can also use the lower section as the mixer, it makes no matter which way you go. I think numerous models of the ways that the IC can be used will evolve along in time. I see several ways to use this. I will upload these files soon. So far it seems as though the chip will have some good separation between the two channels. And it can also be used as a phased modulator. You can also add a potentiometer and balance the outputs to the same level. So that is interesting. I will show that to you in the files soon. Well its working out pretty well. LTSpice is interesting. I make no promise though on how it will come up after being tested on the test bench for noise and other factors. Yet it should work well for some inexpensive radio ideas. It is perfect I think, for use in two way software radios. I always like to watch my sinewave forms for linearity so that is sublime with me. I will keep it linear all the way to the end if possible. Dan
