Forums

+- 90 phase shifter revisited

Started by greysky June 22, 2013
You guys had a lot of great ideas to my original post, but  I realized I 
probably didn't give enough information concerning the application.  In a 
block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine wave 
and the other is for a control voltage, probably a ramp generated by a 16 
bit DAC. The output is the phase shifted sine wave. The ramp causes the sine 
wave to be continuously shifted up to +- 90 degrees. There will also be a 
feedback circuit which will stop the ramp at the appropriate voltage level. 
The sine is being generated by a very low noise ocxo, -110Dbc @ 1 hz from 
center, and the phase shifter needs to not mess this up. Thanks in advance 
for any ideas you may have.

"greysky"
> > You guys had a lot of great ideas to my original post, but I realized I > probably didn't give enough information concerning the application. In a > block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine > wave and the other is for a control voltage, probably a ramp generated by > a 16 bit DAC. The output is the phase shifted sine wave. The ramp causes > the sine wave to be continuously shifted up to +- 90 degrees. There will > also be a feedback circuit which will stop the ramp at the appropriate > voltage level. The sine is being generated by a very low noise > ocxo, -110Dbc @ 1 hz from center, and the phase shifter needs to not mess > this up. Thanks in advance for any ideas you may have. >
** Think you need to consider a PLL used as a phase modulator. BTW: Are you the same guy trying to do weird shit using the AM band ? ... Phil
On Saturday, 22 June 2013 15:45:51 UTC+10, greysky  wrote:
> You guys had a lot of great ideas to my original post, but I realized I=
=20
> probably didn't give enough information concerning the application. In a=
=20
> block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine w=
ave=20
> and the other is for a control voltage, probably a ramp generated by a 16=
=20
> bit DAC. The output is the phase shifted sine wave. The ramp causes the s=
ine =20
> wave to be continuously shifted up to +- 90 degrees. There will also be a=
=20
> feedback circuit which will stop the ramp at the appropriate voltage leve=
l. =20
> The sine is being generated by a very low noise ocxo, -110Dbc @ 1 hz from=
=20
> center, and the phase shifter needs to not mess this up. Thanks in advanc=
e =20
> for any ideas you may have.
So you could use - as Phil Allison said - a voltage-controlled oscillator t= o produce an equally low noise 1MHz sine wave, frequency locked to the firs= t, but phase shifted. Voltage-controlled crystal oscillators do exist - they use a varactor to pu= ll the crystal frequency. The varactor can't pull it very far, so you'd nee= d to start off with two well-matched 1MHz crystals. Some digital frequency synthesis chips can produce a reasonably clean pair = of sine waves with any phase relationship you want to program in. The noise on the synthesised output will be low level high order harmonics.= If your master oscillator is clean and stable, the synthesised waveforms w= on't have any more noise 1kHz away from the centre frequency than the divid= ed down master oscillator frequency. Analog devices have lots of application notes for their - not all that chea= p - DDS chips. http://www.analog.com/en/content/glp_dds/fca.html?gclid=3DCPub-tSZ97cCFQkVp= QodBjwATg You'd have to digitise your phase-shifting voltage to get a digital number = to control your phase shift, but that's no big deal. --=20 Bill Sloman, Sydney=20
On a sunny day (Fri, 21 Jun 2013 22:45:51 -0700) it happened "greysky"
<ftlsite@hotmail.com> wrote in <kq3dmq$92r$1@speranza.aioe.org>:

>You guys had a lot of great ideas to my original post, but I realized I >probably didn't give enough information concerning the application. In a >block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine wave >and the other is for a control voltage, probably a ramp generated by a 16 >bit DAC. The output is the phase shifted sine wave. The ramp causes the sine >wave to be continuously shifted up to +- 90 degrees. There will also be a >feedback circuit which will stop the ramp at the appropriate voltage level. >The sine is being generated by a very low noise ocxo, -110Dbc @ 1 hz from >center, and the phase shifter needs to not mess this up. Thanks in advance >for any ideas you may have.
Bucket brigade controlled delay line You can make one with varicaps and inductors too.
On Fri, 21 Jun 2013 22:45:51 -0700, "greysky" <ftlsite@hotmail.com> wrote:

>You guys had a lot of great ideas to my original post, but I realized I >probably didn't give enough information concerning the application. In a >block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine wave >and the other is for a control voltage, probably a ramp generated by a 16 >bit DAC. The output is the phase shifted sine wave. The ramp causes the sine >wave to be continuously shifted up to +- 90 degrees. There will also be a >feedback circuit which will stop the ramp at the appropriate voltage level. >The sine is being generated by a very low noise ocxo, -110Dbc @ 1 hz from >center, and the phase shifter needs to not mess this up. Thanks in advance >for any ideas you may have.
How accurate does the phase shift have to be? How much amplitude variation can you stand? -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
In article <kq3dmq$92r$1@speranza.aioe.org>, greysky
<ftlsite@hotmail.com> wrote:

> You guys had a lot of great ideas to my original post, but I realized I > probably didn't give enough information concerning the application. In a > block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine wave > and the other is for a control voltage, probably a ramp generated by a 16 > bit DAC. The output is the phase shifted sine wave. The ramp causes the sine > wave to be continuously shifted up to +- 90 degrees. There will also be a > feedback circuit which will stop the ramp at the appropriate voltage level. > The sine is being generated by a very low noise ocxo, -110Dbc @ 1 hz from > center, and the phase shifter needs to not mess this up. Thanks in advance > for any ideas you may have.
Is this a serrodyne application? There is a huge literature on serrodyne methods and applications. Joe Gwinn
On 6/22/2013 7:06 AM, Joe Gwinn wrote:
> In article <kq3dmq$92r$1@speranza.aioe.org>, greysky > <ftlsite@hotmail.com> wrote: > >> You guys had a lot of great ideas to my original post, but I realized I >> probably didn't give enough information concerning the application. In a >> block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine wave >> and the other is for a control voltage, probably a ramp generated by a 16 >> bit DAC. The output is the phase shifted sine wave. The ramp causes the sine >> wave to be continuously shifted up to +- 90 degrees. There will also be a >> feedback circuit which will stop the ramp at the appropriate voltage level. >> The sine is being generated by a very low noise ocxo, -110Dbc @ 1 hz from >> center, and the phase shifter needs to not mess this up. Thanks in advance >> for any ideas you may have. > > Is this a serrodyne application? There is a huge literature on > serrodyne methods and applications. > > Joe Gwinn >
I always thought serrodyne frequency translation took worked with microwave frequencies. I would think a frequency of only 1 Mhz, and phase translation measured in single Hz is a no-go for this method. If I'm wrong, I'd appreciate a link pointing me to relevant literature. Thanks. G-
On 6/22/2013 5:58 AM, John Larkin wrote:
> On Fri, 21 Jun 2013 22:45:51 -0700, "greysky" <ftlsite@hotmail.com> wrote: > >> You guys had a lot of great ideas to my original post, but I realized I >> probably didn't give enough information concerning the application. In a >> block diagram, the phase shifter has 2 inputs, one is for the 1MHz sine wave >> and the other is for a control voltage, probably a ramp generated by a 16 >> bit DAC. The output is the phase shifted sine wave. The ramp causes the sine >> wave to be continuously shifted up to +- 90 degrees. There will also be a >> feedback circuit which will stop the ramp at the appropriate voltage level. >> The sine is being generated by a very low noise ocxo, -110Dbc @ 1 hz from >> center, and the phase shifter needs to not mess this up. Thanks in advance >> for any ideas you may have. > > How accurate does the phase shift have to be? How much amplitude variation can > you stand? > >
Pretty accurate, unfortunately. It all comes down to working within fractions of a hertz at exactly 1 megacycle.The basic idea comes down to being able to make the output waveform match the frequency, waveform, and amplitude of an external non-connected target signal.
> Pretty accurate, unfortunately. It all comes down to working within > fractions of a hertz at exactly 1 megacycle.The basic idea comes down to > being able to make the output waveform match the frequency, waveform, > and amplitude of an external non-connected target signal.
Given the latest revelation here, I don't think you need a phase shifter at all because this won't do what you want it to do. How will an ocxo ever match some random frequency? If there is no frequency lock, you will be phase shifting for ever, but you will run out of range eventually. Either that or I don't understand the problem. [Wouldn't be the first time.] Well at least we have a frequency.
On 6/22/2013 3:29 PM, miso wrote:
>> Pretty accurate, unfortunately. It all comes down to working within >> fractions of a hertz at exactly 1 megacycle.The basic idea comes down to >> being able to make the output waveform match the frequency, waveform, >> and amplitude of an external non-connected target signal. > > Given the latest revelation here, I don't think you need a phase shifter > at all because this won't do what you want it to do. How will an ocxo > ever match some random frequency? If there is no frequency lock, you > will be phase shifting for ever, but you will run out of range > eventually. Either that or I don't understand the problem. [Wouldn't be > the first time.] > > Well at least we have a frequency. >
:-) The target frequency is known. So it is not really a matter of hunting for a random frequency, just matching one you already know about.