[time-nuts] Sine to square wave converter Phase Noise

[Vasco Soares]

Hi,

What comparator did you use in your evaluation? An 74AC04, 74AC14 or other 
LT, AD, etc?

Regards,
Vasco Soares



----- Original Message ----- 
From: <bruce at ko4bb.com>
To: <time-nuts at febo.com>
Sent: Tuesday, July 29, 2014 9:55 AM
Subject: [time-nuts] Sine to square wave converter Phase Noise


> Recently I have been comparing the phase noise of the HOlzworth HX4210 and 
> the
> LTC7957-4.
> I have found that the performance of these devices is comparable with a 
> 10MHz
> sinewave input with a PN noise floor below -160dBc/Hz.
> For offsets below 100Hz the LTC6957-4 is quieter and for offsets below 
> 50Hz or
> so is lower than that of my measurement setup.
> I merely mounted the LTC evaluation board in a diecast metal box to reduce 
> the
> effect of air currents on the LTC7957-4 and used an ultra low noise 3.3V 
> power
> supply (Abracon) to minimise the power supply contribution to the measured 
> phase
> noise.
> Achieving a phase noise performance equal to that on the datasheet was
> relatively easy.
> In fact for low offsets the phase noise is lower than that shown on the
> datasheet.
>
> I've also measured the phase noise of a comparator based sine to CMOS 
> converter
> and its PN floor is about 20dB higher than that of the LTC6957.
> On completion of measurements PN plots for the various sine to square 
> conveters
> tested will be added to the web pages I maintain on Didiers site..
>
>
> Bruce
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