| Electronics > Projects, Designs, and Technical Stuff |
| 1.5 to 3 MHz frequency doubler circuit |
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| Gandalf_Sr:
--- Quote from: langwadt on December 29, 2018, 11:05:05 pm ---I looked at the datasheet and is clear as mud on how the it should be clocked, but afaict it will mute the output if it isn't clocked just right --- End quote --- I have to disagree, I think mud is way clearer than the datasheet. In my case the Amp was giving me no sound and no error indications (by reading the I2C error register). After a month, TI eventually gave help on their e2e forum (after I'd reached out via my contacts in TI) but that was when it was revealed that what I needed was a MCLK at double the SCLK. Seriously TI, from a designer seeking help perspective, you may as well have moved to another planet - maybe you did? To save me some time (I'm on a cruise ship about 100 miles NE from Cape Horn and internet is a bit slow here), can anyone point me to a schematic for the 74HC4046A used with an external divider that will run at 3.3V? |
| Benta:
--- Quote from: Gandalf_Sr on December 30, 2018, 01:15:01 pm --- To save me some time (I'm on a cruise ship about 100 miles NE from Cape Horn and internet is a bit slow here), can anyone point me to a schematic for the 74HC4046A used with an external divider that will run at 3.3V? --- End quote --- Here you go (written by a friend of mine): |
| Gandalf_Sr:
Wow, thanks :D Now 'all' I have to do is remember how to do Laplace transforms. |
| Benta:
--- Quote from: Gandalf_Sr on December 30, 2018, 11:00:29 pm ---Wow, thanks :D Now 'all' I have to do is remember how to do Laplace transforms. --- End quote --- Not necessary, already done for you. Use the "practical example" section. However, you have a different task: with the relatively high frequency from the PFD, you'll need to find an opamp that: - has at least 25 MHz GBW - has rail-to-rail inputs and outputs - is unity-gain stable - will operate at 3.3 V |
| edavid:
--- Quote from: Benta on December 30, 2018, 11:28:56 pm ---Not necessary, already done for you. Use the "practical example" section. However, you have a different task: with the relatively high frequency from the PFD, you'll need to find an opamp that: - has at least 25 MHz GBW - has rail-to-rail inputs and outputs - is unity-gain stable - will operate at 3.3 V --- End quote --- For 2X multiplication of a constant frequency clock, you don't need (or want) a Type 2 loop. The XOR phase detector and a simple passive filter will work fine. |
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