The invention relates to systems and methods for high-sensitivity detection of input bias current. The invention more particularly relates to platforms and techniques for the calibration and measurement of input bias current in op amps or other devices. In embodiments, the platform can incorporate a servo loop connected to a high-sensitivity test amplifier, such as an instrumentation amplifier. The test amplifier can complete a switchable circuit with the servo loop and detect a calibration input bias current for the test platform, without a production device in place. The device under test can be switched into the servo loop, and the total bias current measured with both the device under test and test amplifier in-circuit. The difference between the measured current with the device inserted and the previously measured calibration current represents the bias current for the subject device, without attaching external meters or requiring reference parts of the production type.