[sdiy] monolithic VCO chips for FM??

[Czech Martin]

This would be the traditional "add a zero" approach for high speed
compensation.

This was not my point. The point was: if you send an unipolar current
into a black box that is a triangle oscillator, there must be some kind
of current mirror for direction change, or even a couple of
mirrors. These will add a static error to the f(Ic) characteristic,
even if the integration cap is large and no hf effects are present.

m.c.

-----Original Message-----
From: karl dalen [mailto:dalenkarl at yahoo.se]
Sent: 31 August 2004 03:29
To: Czech Martin; synthplayer88 at spymac.com; synth-diy at dropmix.xs4all.nl
Subject: RE: [sdiy] monolithic VCO chips for FM??


 --- Czech Martin <Martin.Czech at Micronas.com> skrev: 
> And: the frequency range and linearity for the 2206 is speced with
> the typical application circuit in mind: i.e. a potentiometer dial
> for frequency adjustment, like in a lab oscillator.
> If I remeber right this spec is not valid for current drive circuits.
> Then the linearity is better. After all, it is an inverting triangle
> integrator core, why should it be so very nonlinear?
> Perhaps it is the internal switches and mirrors.

Here is an idea Martin, place a low ohm pot (eg,100ohm)(low tempco too, btw)
between one of the cap legs and the cap i/o pin (either one will do-
i suppose)this way you could balance the charge and disscharge current
at the charge cap, and so perhaps change the linearity!! No?

(or was this the idea i used to get a sawtooth wave?? hmm,, cant remember!!:->

Reg
KD
 
> m.c.
> 
> 
> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl
> [mailto:owner-synth-diy at dropmix.xs4all.nl]On Behalf Of
> synthplayer88 at spymac.com
> Sent: 27 August 2004 19:39
> To: synth-diy at dropmix.xs4all.nl
> Subject: Re: [sdiy] monolithic VCO chips for FM??
> 
> 
> 
> 
> On Sun Aug 22  9:59 , Scott Gravenhorst <music.maker at gte.net> sent:
> 
> >James Patchell patchell at cox.net> wrote:
> >>This I find very amazing...(i.e. BS)....If you look at the data sheet for 
> >>the XR2206, sweep linearity is only 8%....this is no where close to 
> >>flat....the ASM-1 oscillator is somewhere around 0.01%....
> 
> 
> Hey guys,
> Has anyone used the maxim 038 VCO chip? The specs looks good, any thoughts?
> 
> http://pdfserv.maxim-ic.com/en/ds/MAX038.pdf
> 
> 
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