se5230 ON Semiconductor, se5230 Datasheet - Page 12

• Manufacturer Part Number: se5230
• Description: Low Voltage Operational Amplifier
• Manufacturer: ON Semiconductor

HALFïWAVE RECTIFIER WITH
RAILïTOïGROUND OUTPUT SWING
both positive and negative supply rails and the output can
also swing to either supply, achieving halfïwave rectifier
functions in either direction becomes a simple task. All that
is needed are two external resistors; there is no need for
diodes or matched resistors. Moreover, it can have either
positiveï or negativeïgoing outputs, depending on the way
the bias is arranged. In Figure 9, the circuit is biased to
ground, while circuit (Figure 10) is biased to the positive
supply. This rather unusual biasing does not cause any
problems with the NE5230 because of the unique internal
saturation detectors incorporated into the part to keep the
PNP and NPN output transistors out of “hard” saturation. It
is therefore relatively quick to recover from a saturated
output condition. Furthermore, the device does not have
parasitic current draw when the output is biased to either rail.
Since the NE5230 input commonïmode range includes
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HalfïWave Rectifier With PositiveïGoing Output Swings
Figure 9. RailïtoïGround Output Swing Referenced to Ground
Figure 10. NegativeïGoing Output Referenced to V
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NE5230, SA5230, SE5230
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This makes it possible to bias the NE5230 into “saturation”
and obtain halfïwave rectification with good recovery. The
simplicity of biasing and the railïtoïground halfïsine wave
swing are unique to this device. The circuit gain can be
changed by the standard op amp gain equations for an
inverting configuration.
cannot respond to oneïhalf of the incoming waveform. It
cannot respond because the waveform forces the amplifier
to swing the output beyond either ground or the positive
supply rail, depending on the biasing, and, also, the output
cannot disengage during this half cycle. During the other
half cycle, however, the amplifier achieves a halfïwave that
can have a peak equal to the total supply voltage. The
photographs in Figure 11 show the effect of the different
biasing schemes, as well as the wide bandwidth (it works
over the full audio range), that the NE5230 can achieve in
this configuration.
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4
It can be seen in these configurations that the op amp
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