The design of a micropower op amp suitable for biomedical applications is presented. A 1-V battery is used for powering the circuit. The quiescent power consumption is under 300 mu A. Current boosting is employed to achieve a maximal output swing very close to the power supply rails for low impedance loads. The input stage consists of p-n-p transistors in differential configuration. The gain stage is a common emitter amplifier with n-p-n transistors. The output stage is a class AB amplifier with both n-p-n and p-n-p transistors driven by unique current amplifiers.
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