[time-nuts] DMTD - analog multiplier vs. diode mixer ?

Li Ang lllaaa at gmail.com
Mon Jan 11 06:51:17 EST 2016


Hi
 Thanks to all the information here. I can put more items to my experiment
list.


Regads
Li Ang, BI7LNQ

2016-01-11 11:28 GMT+08:00 Magnus Danielson <magnus at rubidium.dyndns.org>:

> Moin,
>
> On 01/10/2016 07:56 PM, Attila Kinali wrote:
>
>> On Sun, 10 Jan 2016 14:30:41 +0100
>> Magnus Danielson <magnus at rubidium.dyndns.org> wrote:
>>
>> SR-flipflop? Are you refering to the JK-FF phase detector or the PFD?
>>>>
>>>
>>> A straight SR-flipflop. I would have written JK-FF or PFD if I meant it.
>>> Also, as I mentioned the PFD directly after, you could have concluded
>>> that was not what I intended.
>>>
>>> A SR-flip-flop with no illegal input states is easy to build from a
>>> 74HC00.
>>>
>>
>> The illegal input states were my concern, indeed. And a quick google
>> didn't show up anything to disperse these....not until I started reading
>> the 4046 datasheet in detail.
>>
>
> That's one place to look yes.
>
> But there is one thing about the arangement of the SR FF in the 4046[1]
>> that bothers me:
>> Although S = R = 1 is valid, it does lead to the output oscillating
>> between 0 and 1.
>>
>
> Well, the dynamics of the gates will convert the rising edges on S and R
> into short pulses before hitting the SR core. That is what the additional
> AND gates does if you look at figure 1.
>
> The pulses on Sd and Rd will be about three gate-delays long.
>
> If the Sd and Rd '1' pulses overlap, then it becomes a bit hairer to
> analyze the stability.
>
> However, this works pretty well in reality. Rather than having the +/- 90
> degree property of the XOR gate (which has a triangle phase-response, which
> doesn't always is helpful) it has a +/- 180 degree sawtooth phase-response.
>
> Cheers,
> Magnus
>
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