Purpose of diode at output of single supply op amp

[bonz]

Ran across this schematic which uses single supply op amps (OPA2374) to provide the positive and negative portions of an AC signal. What is the purpose of the diode at the output of the single supply op amp? Wouldn't the output go to (and stay at) ground level when input swings to negative (on the positive op amp and vice versa on the negative)?

I have searched for this online and all I see is uses of this with dual supply op amps which make sense to keep the output from swinging below 0v, but I found nothing on the single supply op amps.

I appreciate your answers in advance.

[MrAl]

Hello,

With many op amps that run off of a single supply, their outputs can not go all the way to 0.000 volts, instead they only get down to maybe 0.025 volts to 0.200 volts.  With that added diode, it drops around 0.600 volts, so the output can get all the way to 0.000 volts even with a single supply.
That's one possibility although one diode is usually enough for that and the pulldown resistor is usually smaller than that 1 Megohm that we see here.
It can also just be there to prevent a negative output.

[magic]

Ask whomever you got this schematic from.

(The noninverting one could be a peak detector, the inverting slightly less so. Either way, net labels look like they may be ESD test fixtures?)

[langwadt]

some kind of push-pull drive for a center tappet transformer?

[Zero999]

They're precision rectifier circuits.

The capacitors provide filtering, but lets concentrate on the DC response.

The diodes are connected in parallel, so can be treated as single diodes.

The top one is half wave and the bottom full wave but R6 on the output attenuates the positive cycles because when the op-amp's output is negative, the input is connected to the output via R& and R5.

 precision rectifier.asc (1.95 kB - downloaded 7 times.)

A solution is to the full wave rectifier is to select the feedback resistors so the op-amp inverting amplifier's attenuation matches that of the output resistor and add an amplifier to raise the gain back to unity.

 precision rectifier.asc (1.95 kB - downloaded 6 times.)