On 20 January 2018 at 15:27 Bob kb8tq <kb8tq@n1k.org> wrote:

 Hi

 My main point is that a +22 dbm (or even 16 dbm) OCXO is a *very* rare item. If your
 signal generator is set to +22 dbm … shame on you. If the part can do well over +7 to
 +13 dbm, that will cover the vast majority of the 10 MHz oscillators / signal sources out there.

 Bob

     On Jan 19, 2018, at 8:51 PM, Bruce Griffiths <bruce.griffiths@xtra.co.nz> wrote:

     Even the modern PICs spec 50mA max input currents.
     Simulation indicates 20mA peak diode currents without the 330 ohm resistors for a 2V pp input, even more for higher input signal levels. If one can guarantee that input is around 1V pp then the extra diodes and resistors aren't required. If its possible that an input of 16dBm or more may be used then the extra diodes and resistors are required. I simulated the circuit for inputs up to +22dBm.
     Current flowing in the IC protection diodes can degrade the timing jitter substantially (tens of picosec for HCMOS).

     Bruce

         On 20 January 2018 at 14:34 Bob kb8tq <kb8tq@n1k.org> wrote:

         Hi

         Unless you really beat on the thing for days on end, you can do without the 330 ohm and 100 ohm
         resistors (along with the two diodes). Most modern gates have pretty robust protection diodes. The
         source impedance is high enough after the transform that the available current is pretty low. On a
         NC7SZ125 the negative diode is rated for 50 ma max and the positive diode is rated for 20 ma

         Some math:

         If the two 1K’s properly terminate the circuit, you have a 250 ohm source. (500 ohm load and 500 ohm
         transformed from the sine input). A 1V overdrive (1/2 V + and 1/2 V -) will put 2 ma into the diodes on the
         peaks. The more likely case is that the negative is hit a bit harder. The bias is most likely a bit below
         1/2 Vcc for best symmetry.

         None of this is to say you *should* hit the diodes. No matter what sort they are, the performance will
         degrade a bit when you do. How much is of course a “that depends”. Most of us are not driving the
         gate with a -180 dbc/Hz source and expecting -177 out of the gate.

         Bob

             On Jan 19, 2018, at 8:14 PM, Bruce Griffiths <bruce.griffiths@xtra.co.nz> wrote:

             Something like the attached circuit is suitable for driving the MCU clock input directly.
             The diodes should be schottky signal diodes like the 1N5711 series. The series resistors limit the diode peak current and the CLK input protection network current. It should work with inputs from 1V pp to 8Vpp. If SMT components were used it should all fit on a DIP compatible daughter board.

             Bruce

                 On 20 January 2018 at 12:37 Bob kb8tq <kb8tq@n1k.org> wrote:

                 Bob

                 With a 1V p-p sort of output, a simple matching network will get you into the 4 to 6V p-p range.
                 Drive that into a 5V compatible CMOS gate and move on …. If you have a super hot output, put
                 a 3 db pad on it.

                 Bob

                     On Jan 19, 2018, at 5:40 PM, Tom Van Baak <tvb@LeapSecond.com> wrote:

                         Tom
                         What's the input signal amplitude?
                         What's the desired output signal (eg 5V CMOS, 3.3V CMOS etc)?
                         Bruce

                     It's for a typical 5 or 10 MHz OCXO / Rb / Cs with sinewave output; say, 1 Vpp. The output should be 3.3 or 5 V depending on what the MCU needs. It doesn't have to have stunning performance: think breadboard, PIC, Arduino sort of stuff. I was looking for something in a PDIP-8 package; the same as all the picDIV or picPET chips I use. That's why older parts like µA9637 / DS9637 came to mind.

                     /tvb

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                 <PIC_CLK_Network.gif>

Yes, I was just trying to see how far the circuit could be pushed (+27dBm input was still OK). With +13dBm input peak diode current without 100R and 330R resistors is about 20mA for the 3.3V circuit with an impedance step up from 50 to 400 ohm. My 100MHz Wenzel OCXO has an output of around +19dBm or so. I measure the output of all my sources before I connect them. Bruce > > On 20 January 2018 at 15:27 Bob kb8tq <kb8tq@n1k.org> wrote: > > Hi > > My main point is that a +22 dbm (or even 16 dbm) OCXO is a *very* rare item. If your > signal generator is set to +22 dbm … shame on you. If the part can do well over +7 to > +13 dbm, that will cover the vast majority of the 10 MHz oscillators / signal sources out there. > > Bob > > > > > > On Jan 19, 2018, at 8:51 PM, Bruce Griffiths <bruce.griffiths@xtra.co.nz> wrote: > > > > Even the modern PICs spec 50mA max input currents. > > Simulation indicates 20mA peak diode currents without the 330 ohm resistors for a 2V pp input, even more for higher input signal levels. If one can guarantee that input is around 1V pp then the extra diodes and resistors aren't required. If its possible that an input of 16dBm or more may be used then the extra diodes and resistors are required. I simulated the circuit for inputs up to +22dBm. > > Current flowing in the IC protection diodes can degrade the timing jitter substantially (tens of picosec for HCMOS). > > > > Bruce > > > > > > > > > > On 20 January 2018 at 14:34 Bob kb8tq <kb8tq@n1k.org> wrote: > > > > > > Hi > > > > > > Unless you really beat on the thing for days on end, you can do without the 330 ohm and 100 ohm > > > resistors (along with the two diodes). Most modern gates have pretty robust protection diodes. The > > > source impedance is high enough after the transform that the available current is pretty low. On a > > > NC7SZ125 the negative diode is rated for 50 ma max and the positive diode is rated for 20 ma > > > > > > Some math: > > > > > > If the two 1K’s properly terminate the circuit, you have a 250 ohm source. (500 ohm load and 500 ohm > > > transformed from the sine input). A 1V overdrive (1/2 V + and 1/2 V -) will put 2 ma into the diodes on the > > > peaks. The more likely case is that the negative is hit a bit harder. The bias is most likely a bit below > > > 1/2 Vcc for best symmetry. > > > > > > None of this is to say you *should* hit the diodes. No matter what sort they are, the performance will > > > degrade a bit when you do. How much is of course a “that depends”. Most of us are not driving the > > > gate with a -180 dbc/Hz source and expecting -177 out of the gate. > > > > > > Bob > > > > > > > > > > > > > > On Jan 19, 2018, at 8:14 PM, Bruce Griffiths <bruce.griffiths@xtra.co.nz> wrote: > > > > > > > > Something like the attached circuit is suitable for driving the MCU clock input directly. > > > > The diodes should be schottky signal diodes like the 1N5711 series. The series resistors limit the diode peak current and the CLK input protection network current. It should work with inputs from 1V pp to 8Vpp. If SMT components were used it should all fit on a DIP compatible daughter board. > > > > > > > > Bruce > > > > > > > > > > > > > > > > > > On 20 January 2018 at 12:37 Bob kb8tq <kb8tq@n1k.org> wrote: > > > > > > > > > > Bob > > > > > > > > > > With a 1V p-p sort of output, a simple matching network will get you into the 4 to 6V p-p range. > > > > > Drive that into a 5V compatible CMOS gate and move on …. If you have a super hot output, put > > > > > a 3 db pad on it. > > > > > > > > > > Bob > > > > > > > > > > > > > > > > > > > > > > On Jan 19, 2018, at 5:40 PM, Tom Van Baak <tvb@LeapSecond.com> wrote: > > > > > > > > > > > > > > > > > > > > > > > > > > Tom > > > > > > > What's the input signal amplitude? > > > > > > > What's the desired output signal (eg 5V CMOS, 3.3V CMOS etc)? > > > > > > > Bruce > > > > > > > > > > > > > > > > > > > > > > > > > > It's for a typical 5 or 10 MHz OCXO / Rb / Cs with sinewave output; say, 1 Vpp. The output should be 3.3 or 5 V depending on what the MCU needs. It doesn't have to have stunning performance: think breadboard, PIC, Arduino sort of stuff. I was looking for something in a PDIP-8 package; the same as all the picDIV or picPET chips I use. That's why older parts like µA9637 / DS9637 came to mind. > > > > > > > > > > > > /tvb > > > > > > > > > > > > _______________________________________________ > > > > > > time-nuts mailing list -- time-nuts@febo.com > > > > > > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > > > and follow the instructions there. > > > > > > > > > > > > > > > > > > > > > > _______________________________________________ > > > > > time-nuts mailing list -- time-nuts@febo.com > > > > > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > > > and follow the instructions there. > > > > > > > > > > <PIC_CLK_Network.gif> > > > > > > > > > > > > > > > > > > > > > > > > > > > > >

-------- In message <eb956eca-4534-0463-031b-232f8bdbd62f@earthlink.net>, jimlux writes: >> I played with that, I used a small transformer to balance the signal >> and then into LVDS receiver through a voltage divider. Worked well, >> but I didn't measure the jitter, it was just for a micro-controller. > >You can also do it with capacitive dc block to one side, and some >resistors - the ap notes describe it. The receivers are a fairly high Z >input, so you pick the voltage divider resistors to make the termination >resistance right for the incoming signal. Yes, but that doesn't give you galvanic isolation, which I think is almost mandatory unless it is a metrology situation. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.

Tom might have started this as I was playing around with PICDIV and had asked him the best conditioning circuit. Turned out I had all the parts to copy the TADD-2 including the mini circuits transformer so that’s what I did. It works well, pretty sensitive, etc. I’ve also used the bias trick with a TTL or CMOS buffer when I needed to convert SPIDF signals to baseband for driving an optical connection. Now that I had the input conditioned, I need to drive a 50ohm load with the signal coming from the PICDIV. Can someone point me at a circuit using transistors and 10V if possible? I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz down to 10Khz. Thanks Jerry > On Jan 20, 2018, at 11:21 AM, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote: > > -------- > In message <eb956eca-4534-0463-031b-232f8bdbd62f@earthlink.net>, jimlux writes: > >>> I played with that, I used a small transformer to balance the signal >>> and then into LVDS receiver through a voltage divider. Worked well, >>> but I didn't measure the jitter, it was just for a micro-controller. >> >> You can also do it with capacitive dc block to one side, and some >> resistors - the ap notes describe it. The receivers are a fairly high Z >> input, so you pick the voltage divider resistors to make the termination >> resistance right for the incoming signal. > > Yes, but that doesn't give you galvanic isolation, which I think is almost > mandatory unless it is a metrology situation. > > -- > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > phk@FreeBSD.ORG | TCP/IP since RFC 956 > FreeBSD committer | BSD since 4.3-tahoe > Never attribute to malice what can adequately be explained by incompetence. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

 On 21 January 2018 at 08:43 Jerry Hancock <jerry@hanler.com> wrote:

 Tom might have started this as I was playing around with PICDIV and had asked him the best conditioning circuit. Turned out I had all the parts to copy the TADD-2 including the mini circuits transformer so that’s what I did. It works well, pretty sensitive, etc. I’ve also used the bias trick with a TTL or CMOS buffer when I needed to convert SPIDF signals to baseband for driving an optical connection.

 Now that I had the input conditioned, I need to drive a 50ohm load with the signal coming from the PICDIV. Can someone point me at a circuit using transistors and 10V if possible?

 I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz down to 10Khz.

 Thanks

 Jerry

     On Jan 20, 2018, at 11:21 AM, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:

     --------
     In message <eb956eca-4534-0463-031b-232f8bdbd62f@earthlink.net>, jimlux writes:

             I played with that, I used a small transformer to balance the signal
             and then into LVDS receiver through a voltage divider. Worked well,
             but I didn't measure the jitter, it was just for a micro-controller.

         You can also do it with capacitive dc block to one side, and some
         resistors - the ap notes describe it. The receivers are a fairly high Z
         input, so you pick the voltage divider resistors to make the termination
         resistance right for the incoming signal.

     Yes, but that doesn't give you galvanic isolation, which I think is almost
     mandatory unless it is a metrology situation.

     --
     Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
     phk@FreeBSD.ORG | TCP/IP since RFC 956
     FreeBSD committer | BSD since 4.3-tahoe
     Never attribute to malice what can adequately be explained by incompetence.

     _______________________________________________
     time-nuts mailing list -- time-nuts@febo.com
     To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
     and follow the instructions there.

 _______________________________________________
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
 and follow the instructions there.

An npn emitter follower with collector connected to the 10V supply will produce a 4.2V swing in a 50 ohm load. However it only works well if reflections from the load are small. Otherwise, assuming that you want a 0-5V signal at the 50 ohm load its possible to build a back matched driver using 3 BJTs that will switch 200mA into a 25 ohm load with transition times around 5ns or so. Faster transition times require using transistors with ft's somewhat greater than 300MHz. However the 10V rail current increases to 200mA when the output is 5V at the 50 ohm load. Bruce > > On 21 January 2018 at 08:43 Jerry Hancock <jerry@hanler.com> wrote: > > Tom might have started this as I was playing around with PICDIV and had asked him the best conditioning circuit. Turned out I had all the parts to copy the TADD-2 including the mini circuits transformer so that’s what I did. It works well, pretty sensitive, etc. I’ve also used the bias trick with a TTL or CMOS buffer when I needed to convert SPIDF signals to baseband for driving an optical connection. > > Now that I had the input conditioned, I need to drive a 50ohm load with the signal coming from the PICDIV. Can someone point me at a circuit using transistors and 10V if possible? > > I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz down to 10Khz. > > Thanks > > Jerry > > > > > > On Jan 20, 2018, at 11:21 AM, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote: > > > > -------- > > In message <eb956eca-4534-0463-031b-232f8bdbd62f@earthlink.net>, jimlux writes: > > > > > > > > > > > > > > > > > > I played with that, I used a small transformer to balance the signal > > > > and then into LVDS receiver through a voltage divider. Worked well, > > > > but I didn't measure the jitter, it was just for a micro-controller. > > > > > > > > > > > > > > You can also do it with capacitive dc block to one side, and some > > > resistors - the ap notes describe it. The receivers are a fairly high Z > > > input, so you pick the voltage divider resistors to make the termination > > > resistance right for the incoming signal. > > > > > > > > > > Yes, but that doesn't give you galvanic isolation, which I think is almost > > mandatory unless it is a metrology situation. > > > > -- > > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > phk@FreeBSD.ORG | TCP/IP since RFC 956 > > FreeBSD committer | BSD since 4.3-tahoe > > Never attribute to malice what can adequately be explained by incompetence. > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. >

How about using a single 8-pin DIP IC that is under $2.50? The Microchip MIC4422AYN "gate driver" takes a 3.3V signal in and produces a fast rail-to-rail output swing, with a 4.5V to 18V supply range. Typical output resistance is sub 1 Ohm, so not a problem driving a series back-terminated 50 Ohm load. Note the 4422's rise and fall times are specified with a 10,000pF load, given the primarily resistive load in this case the rise and fall should be sub 10 ns (per p.5 of the data sheet). But do use beefy lo-Z traces and hefty broadband supply bypassing, the MIC4422 can pump up to 9A into its intended load. Bob L. > Sent: Saturday, January 20, 2018 at 2:43 PM > From: "Jerry Hancock" <jerry@hanler.com> > To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> > Subject: Re: [time-nuts] minimalist sine to square > > ... > > Now that I had the input conditioned, I need to drive a 50ohm load with the signal coming from the PICDIV. Can someone point me at a circuit using transistors and 10V if possible? > > I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz down to 10Khz. > > Thanks > > Jerry

 On 22 January 2018 at 07:31 Robert LaJeunesse <lajeunesse@mail.com> wrote:

 How about using a single 8-pin DIP IC that is under $2.50? The Microchip MIC4422AYN "gate driver" takes a 3.3V signal in and produces a fast rail-to-rail output swing, with a 4.5V to 18V supply range. Typical output resistance is sub 1 Ohm, so not a problem driving a series back-terminated 50 Ohm load. Note the 4422's rise and fall times are specified with a 10,000pF load, given the primarily resistive load in this case the rise and fall should be sub 10 ns (per p.5 of the data sheet). But do use beefy lo-Z traces and hefty broadband supply bypassing, the MIC4422 can pump up to 9A into its intended load.

 Bob L.

     Sent: Saturday, January 20, 2018 at 2:43 PM
     From: "Jerry Hancock" <jerry@hanler.com>
     To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com>
     Subject: Re: [time-nuts] minimalist sine to square

     ...

     Now that I had the input conditioned, I need to drive a 50ohm load with the signal coming from the PICDIV. Can someone point me at a circuit using transistors and 10V if possible?

     I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz down to 10Khz.

     Thanks

     Jerry

I wonder what the timing jitter is like. It may be useful to measure it along with its additive PN. Bruce > > On 22 January 2018 at 07:31 Robert LaJeunesse <lajeunesse@mail.com> wrote: > > How about using a single 8-pin DIP IC that is under $2.50? The Microchip MIC4422AYN "gate driver" takes a 3.3V signal in and produces a fast rail-to-rail output swing, with a 4.5V to 18V supply range. Typical output resistance is sub 1 Ohm, so not a problem driving a series back-terminated 50 Ohm load. Note the 4422's rise and fall times are specified with a 10,000pF load, given the primarily resistive load in this case the rise and fall should be sub 10 ns (per p.5 of the data sheet). But do use beefy lo-Z traces and hefty broadband supply bypassing, the MIC4422 can pump up to 9A into its intended load. > > Bob L. > > > > > > Sent: Saturday, January 20, 2018 at 2:43 PM > > From: "Jerry Hancock" <jerry@hanler.com> > > To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com> > > Subject: Re: [time-nuts] minimalist sine to square > > > > ... > > > > Now that I had the input conditioned, I need to drive a 50ohm load with the signal coming from the PICDIV. Can someone point me at a circuit using transistors and 10V if possible? > > > > I am trying to duplicate one channel of the TADD2 so I can bring 10Mhz down to 10Khz. > > > > Thanks > > > > Jerry > > > > >