English: Bootstrapped diamond follower. Nodes A+ and A- now can swing beyond power supply rails. Bootstrapping emitter networks of input transistors enables larger output voltage and current swing than a simple "resistive current source" circuit can deliver. Bootstrapping collectors as well adds the benefit of removing the Early effect (better linearity) and the opportunity to use low-voltage transistors in relatively high-voltage environment. The obvious drawback is the need for fairly large bootstrapping capacitors.