A prototype freq divider has been made which works up to ~40MHz.
74HC4060 (14bit binary ripple counter) divides the freq of the input signal, which is comverted by the comparator LT1016
into the rectangular signal. The division rate is 2^14.
Attachment1: Circuit diagram
Attachment2: Photo, the prototype bread board
Attachment3: Photo, the spectrum of the freq divided output. The 40MHz input has been divided into 2.4k.
There are the 3rd and 5th harmonics seen. The peak was pretty sharp but the phase noise was not evaluated yet.
The circuit was made on the prototype bread board which is apparently unsuitable for RF purposes.
Indeed, it was surprising to see its working up to 40MHz...
In order to increase the maximum freq of the system we need the following considerations
- RF PCB board
- Input RF buffer (or amplifier) with a 50Ohm input impedance.
- Faster comparator. LT1016 has the response time of 10ns, which is not enough fast.
- Faster counter. Faster chip 74HC4020 has already been ordered.
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