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ddwyer wrote:
In article vLWrc.13935$JC5.1310262@attbi_s54, Scott Stephens ddwyer wrote: A multimode delay line oscillator can be achieved by introducing a peaked gain response at the required overtone. The delay line can be multioctave and the phase slope will be proportional the the delay. It may go through many 360 deg phase rotations over its bandwidth. The phase slope is proportional to the delay. When I think of phase slope, I think of inductance or capacitance, reactance based phase shift. An amplifier with much shallower phase slope An amplifier with broad bandwidth, having the real, resistive impedance greater than the reactive impedance? can still have sufficient selectivity to determine which particular 360 deg rotation is oscillated. This has been done successfully with PAL bulk acoustic delay lines. I've played around with ring oscillators made from 3 (or more) transistors, 3 FETs and my favorite, 3 CMOS unbuffered inverter gates. I find I can tune these sine-wave ring oscillators between 8 and 20 : 1 range, by changing the bias gate voltage and source current. Perhaps more, after I try a few tricks. 20:1 isn't bad, but I don't see why I shouldn't be able to get 100,000:1 out of a transconductance-tuned phase shift oscillator. I guess you'd say these have a very shallow "phase slope". I was hoping to use them as a wide-band tuned circuit, by setting the gain just under the oscillation point. But I found they are very sensitive to harmonics. I can bet a delay line oscillator is going to have this same problem then? I've tried several ways to make a clean wide-range sine-wave oscillator and regenerative variable tuned circuit. -- Scott ********************************** DIY Piezo-Gyro, PCB Drill Bot & More Soon! http://home.comcast.net/~scottxs/ ********************************** |
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