[sdiy] Odp: Re: SAW core VCO flyback time

[Ian Fritz]

Sounds familiar:
http://ijfritz.byethost4.com/sy_cir4.htm


On 8/28/2016 11:28 AM, Ben Bradley wrote:
> I've designed but not yet built a triangle oscillator using a single
> integrator and mux on the input. This uses two current outputs from
> the exponential converter, one going to a current mirror, so there's
> the same amount of current in both directions. The mux, driven by the
> usual comparator with large hysteresis, switches the integrator input
> between these two current sources. I'm not sure how a disconnected
> current source will act when connected, but an extra switch can
> connect the non-active current source to ground. This way the current
> sources are always (except for switching times) connected to a virtual
> or actual ground. Thinking another moment, a signal diode/1N4148
> between each current source and ground, connected to forward conduct
> when the mux switches off, may be a better solution.
>
> Good symmetry of course depends on the current sources being as close
> as possible.
>
> What parts do people use for multiplexers? I recently got a Vishay
> thru-hole DG613 from Digikey (DG613DJ-E3-ND), and then got an email
> that the thru-hole part is on Last Time Buy. It's expensive at $3, but
> it switches remarkably fast. It has odd power voltage requirements and
> will only do about +/-10V, bu that's still better than the standard
> CMOS series parts. I've since done more research on analog switches
> running on +/-15V, and it appears the minimum cost is around $1.50 to
> $2.
>
>


-- 
ijfritz.byethost4.com