Although modern integrated circuit operational amplifiers ease linear
circuit design, IC processing limits amplifier output power. Many
applications, however, require substantially greater output voltage
swing or current (or both) than IC amplifiers can deliver. In these
situations an output “booster,” or post amplifier, is required to
achieve the needed voltage or current gain. Normally, this stage is
placed within the feedback loop of the operational amplifier so that the
low drift and stable gain characteristics of the amplifier are
retained.
Because the booster is a gain stage with its own inherent AC
characteristics, the issues of phase shift, oscillation, and frequency
response cannot be ignored if the booster and amplifier are to work well
together. The design of booster stages which achieve power gain while
maintaining good dynamic performance is a difficult challenge. The
circuitry for boosters will change with the application’s
requirements,which can be very diverse.
This application note explains the following designs with diagrams and definitions.
- 200 mA Current Booster
- Ultra High Speed Fed-Forward Current Booster
- Voltage-Current Booster
- ±120V Swing Booster
- High Current Booster
- Indestructible, Floating Output Booster
- 1000V-300 mA Booster
- 300V Output Booster
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