Sinusoidal phase locked loop IC: Anyone know of one 1

[questionguy]

Hi, I can't seem to find any IC phase locked loop that outputs a sinusoid. All the ones I've found have square wave and triangle wave outputs, and a digital phase comparator. I realize I can just do a triangle to sine conversion but there must be an IC out there that does it all.

Thanks.

 

[benta]

As far as I remember, the old MC1648 and MC12148 VCOs had sine output, but to my knowledge they are both obsolete.

Benta.

 

[zappedagain]

What frequency range? What voltage?

 

[questionguy]

The frequency is about 10-100Hz. The amplitude doesn't really matter to me, I guess >=1V, <5V would be nice. Although seeing how elusive this IC is, I'll settle for a 50V sine if I have to and then just attenuate.

 

[sreid]

How about A/D converting the input signal to a DSP and doing everything digitally?

 

[benta]

10...100 Hz? Silly me, I was in the 100 MHz range. Just shows how an incomplete first question derails things.

To your problem: my solution would be to multiply your input frequency with a PLL multiplier, perhaps ~1000 times.
Use the counter in the multiplier to drive a ROM containing a sine lookup table. D/A convert, filtering out the high-frequency "fuzz" is easy.

Cheers,

Benta.

 

[questionguy]

Thanks all. I'm really not looking for a work around. I know how I can do this with the readily available square wave output PLLs, I just figured there had to be a single IC out there that would give me the sine I'm looking for.

This is just a part of my circuit so I don't want the PLL to take up half a breadboard.

 

[Comcokid]

Your need for a sine PPL IC at low frequencies is similar to the AC-error-loop-pwm-control circuits used in many DC/AC inverters. But these circuits are not single-chip. Most inverters can be adjusted from 10 to over 400 Hz by using a variable frequency sine reference instead of the 50 or 60 Hz crystal derived reference (I provide this info to indicate the freq range of this control circuit).

The closest to single chip are uP design applications for inverter control from Microchip where the sine is in the software.

 

[Warpspeed]

In the past I have used one of the function generator chips that has separate sine/square/triangle outputs as a VCO.
Fairly effective down to below 1Hz.

The square wave output is used in a conventional PLL, and the fairly good sine wave output drives the external load.

A two chip solution is probably the best you can hope for.

 

[notaguest]

Check out the AD5932 or similar. It's a SMT part and requires programming via a micro, but it provides an Iout sine wave that can be converted to a sine voltage via an opamp.

 

[notaguest]

I'm not sure whether you require a variable frequency sine ouptut or the functionality of a PLL.

Another option is the XR2206 to generate the sine output, and use the XR2211 to provide PLL functionality.

They have both been around a long time, but are still currently manufactured.