SNVS420D November 2008 – May 2018 LM7705
The limitations of the output stage of the op amp, as indicated in both examples, can be omitted by using a dual supply op amp. The output stage of the used op amp can then still swing from 50 mV of the supply rails. However, the functional output range of the op amp is now from ground level to a value near the positive supply rail. Figure 26 shows the output drive of an amplifier in a true zero output voltage application.
Disadvantages of this solution are:
A better solution is to use the LM7705. This low-noise negative bias generator has some major advantages with respect to a dual-supply solution:
In the Typical Application section, a typical amplifier application will be evaluated. The performance of an amplifier will be measured in a single supply configuration. The results will be compared with an amplifier using a LM7705 supplying a negative voltage to the bias pin.