Advanced Pseudo Differential Amplifier with Output Common Mode Regulation and Phase Shift Retention

In the past decades, the use of sensors in the automotive sector has evolved exponentially. The Anti-Lock Brakingsystem (ABS) has been improved considerably. These systemsuse magnetic sensors (Giant Magneto Resistance (GMR)) witha pole toothed wheel to generate a signal. Currently there areused two preamplifiers to process the information from theGMR bridge to detect speed and direction. In the new ABSsensor architecture, both amplitude and phase information canbe processed simultaneously by a single pre-amplifier to detectspeed and direction. The goal is to develop a part of that system, a pseudo differential amplifier to be integrated on chip usingBiCMOS technology. It amplifies the signal received from anew GMR transducer bridge in the ABS. This paper addressesthe design of a new implementation of preamplifier "AdvancedPseudo Differential Amplifier (PDA)" by maintaining the phaseshift and the common mode of the GMR transducer output. This"Advanced PDA" must conform to tight design specifications, such as an output common mode of 1:25 V ±10 %, an inputreferred noise of 5 µV/√Hz, a gain of 11 ±5 %, an attenuation@ 3 kHz of +2 %, a linearity of 97 % (@ an input signal amplitude of ±100 mV), and finally differential phase variationsof 10° (input vs output) for implementation in ABS systems.