Abstract: A system and method for compensating an amplifier apparatus for low frequency and/or DC components of an externally applied input signal as well as for any voltage offsets contributed by the amplifier circuitry. Band-limited servo feedback is applied to predetermined nodes in the forward gain path to null out unwanted signal components, leaving a residual signal that, when amplified, will be centered around ground, so that the full dynamic range of the amplifier system may be utilized. Consequently, the signal-to-noise ratio available at the output of the amplifier system will be maximized. The servo compensation may either operate in continuous time, or it may be held constant once a suitable level of compensation has been established, or it may be adjusted from time to time to accommodate slow variations of the average DC component of the input signal.

Abstract: A method and apparatus for reducing imbalances among the outputs of a plurality of driver devices connected in a parallel configuration to drive a common load. One driver is designated as the master, and suitable servo circuitry is provided to each of the other slave drivers, each servo being operative to force the output of its associated slave driver to accurately track the output of the designated master driver. The servo circuitry may be disposed to equalize either the output voltages or output currents of the several drivers to ensure load balancing among the drivers, to reduce cross-conduction currents and attendant power wastage and improve dynamic performance. The plurality of drivers may either operate in an open-loop configuration, or be enclosed within an overall negative feedback loop under the control of a separate controller that itself may be an amplifier.

Abstract: A time varying electrical excitation(s) is applied to a system containing biologic and/or non-biologic elements, whereupon the time-varying electrochemical or electrical response is detected and analyzed. For biologic specimens, the presence, activity, concentration or relative quantity, and certain inherent characteristics of certain target substances (hereinafter referred to as “target analytes”) within, or comprising, the specimen of interest may be determined by measuring either the current response induced by a voltage-mode excitation, or the voltage response induced by a current-mode excitation. Labeling or marker techniques may be employed, whereby electrochemically active auxiliary molecules are attached to the substance to be analyzed, in order to facilitate or enhance the electrochemical or electrical response.