I'm designing an audio circuit running on ±15V supplies, which has a need for precision +12V and -5V rails. These must source (from 12V) and sink (from -5V) up to ~20mA to power a CEM3340 oscillator and some ancillary components. Absolute precision of these +12V and -5V supplies is not critical (±1% would be OK) but I would like to minimise temperature dependence as far as possible, within a maximum budget of around $3. Load regulation needs to be good, as the CEM3340 current draw will vary with time across the oscillation cycle.
The circuit already uses several OPA1679 op-amps (which can source/sink over 20mA) and a 5V precision reference. So one solution seemed to be using two amplifiers from an OPA1679 in straightforward non-inverting and inverting configurations to give +12V and -5V from the existing 5V reference.
- Is using an op-amp to provide the power rails in this way sensible? If so,
- How should I make sure that the new power rails are properly decoupled? I understand that putting decoupling capacitors across the new op-amp outputs may cause instability, but don't know how to predict or mitigate this.
If op-amp outputs are not sensible here, what would be the best strategy for getting these power rails?