Martin Klingensmith wrote:
<snip>
> I need 2 identical PWM signals 180 degrees out of phase: [view with a
> fixed-width font]
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<snip>

Hi Martin,

I believe the following will satisfy your requirements.

On the first XOR one input is tied high and its other input is fed the
original square wave.  The second XOR has one input tied low and its other
input is fed the original square wave.

The result is two outputs, one of which is a replica of the original input,
the other the inverse of the original input.

Inputs    Outputs
A   B       Y

L   L       L     <-- input A held low
L   H       H     <-- input B fed with sq wave

H   L       H     <-- input A held high
H   H       L     <-- input B fed with sq wave

The 74AC86 quad XOR has propagation delays and state changes 11 nanoseconds
or less for a wide temperature range.  Since one would probably use a pair
of gates from the same quad package these tolerances would probably be
tighter in practice.

Generate the input from a PIC and off you go.

Joe, K9HDE

PS  If Denny Esterline's comments are correct concerning required 'off'
times, then the above may be true but of no use to you at this time.  8-)

PPS  Are you sure about an inverter not being suitable?

Input    Output
A          Y

L          H
H          L

The original signal is the first output, the output of the inverter is the
second.

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