Nah, talk more shit
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# TIMDAC Theory of Operation
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TIMDAC is _not_ a PWM DAC, where a waveform is generated whose average value
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equals the desired output, and then filtered all the way down to DC. While this
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is definitely a feasible way to implement a precision DAC, the level of
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filtering required to achieve usable 15-bit or 16-bit performance severely
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limits the update rate, especially if using a scanning sequence to generate
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more outputs than available PWM channels. Also, to truly achieve equivalent
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specs to TIMDAC, other circuits implemented here (such as the constant-impedance
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reference chopper) become necessary. While you could use a PWM DAC and get most
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of the way there, TIMDAC takes it that little smidge farther into commercial-
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equivalent DAC performance.
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equals the desired output, and then filtered all the way down to DC. This method
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is often proposed, but is not really feasible at high precision — to achieve
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1 LSB of filtered ripple, at 15 bits with a 36 MHz counting frequency, a
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first-order filter will settle in about a _minute_. (A basic second-order filter
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will settle in about a second, which is much much better, but still very
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limiting.) Furthermore, some of the same measures TIMDAC uses to mitigate other
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problems at high precision, for example the constant-impedance reference
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chopper, are still necessary to get these specs.
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Instead of PWM, TIMDAC uses an integrating sample-and-hold topology. A single
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pulse is integrated, producing a ramp from 0 up to the product of the pulse
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