Abstract: An amplifier circuit has a multi-stage amplifier, a compensation capacitor, and compensation circuits. The multi-stage amplifier has amplifiers cascaded between an input port and an output port of the multi-stage amplifier. The amplifiers include at least a first-stage amplifier, a second-stage amplifier and a third-stage amplifier. The compensation capacitor is coupled between the output port of the multi-stage amplifier and an output port of the first-stage amplifier. The compensation circuits include a first compensation circuit and a second compensation circuit. The first compensation circuit is coupled to the output port of the first-stage amplifier. The second compensation circuit is coupled to an output port of the second-stage amplifier.

Abstract: Some embodiments of the invention relate to a DC offset correction circuit comprising a feedback loop having a DAC controlled by a reconfigurable ADC, which determines (e.g., tracks) the mean value of a modulated input signal. The circuit operates according to two phase process. In a first “pre-modulation” tracking phase, an input signal is tracked by the ADC, which is configured to output the input signal's mean value as a digital code equivalent to the input mean value. The output of the ADC is provided to a DAC, which provides an analog representation of the mean value to an adder that subtracts the mean value from the modulated input signal to generate a bipolar adjusted input signal. In a second “modulation” phase, the estimated mean value is held constant, so that the bipolar adjusted input signal may be provided to an activated modulation circuit for improved system performance.

Abstract: The in-phase channel 28 of a complex demodulated resonator data output signal 12 should contain all of the sensed information, and the quadrature-phase channel 32 should contain none of it. This will not happen if the phase of the reference signal 14 is incorrect. The phase may be adjusted by first filtering each demodulated channel with a respective low-pass dc-blocked filter 34, 38 which passes only the frequencies of the sensed information. If the sensed information gets through on both channels, then there will be a non-zero cross-correlation between the channels. This cross-correlation can be servoed to a minimum by use of a feedback signal 22. Doing so will cause all of the sensed information to be in one channel 28, and diagnostic information to be in the other channel 32.