Patent ID: 7981043

Claim:
A non-invasive electronic apparatus for measuring blood pressure, which comprises a cuff, a gas pump connected with the cuff, a first pressure sensor connected with the cuff, a second pressure sensor connected with the cuff for overpressure and overtime protection, a first solenoid valve unit for deflation, a first microprocessor, a combined precise amplification circuit including a voltage follower, a preamplifier and an output amplifier, and a second solenoid valve which is connected between the cuff and the first pressure sensor, wherein the voltage follower has an input terminal connected with an output terminal of the second pressure sensor, the preamplifier has an input terminal connected with an output terminal of the voltage follower and an input terminal connected with the output terminal of the second pressure sensor, and the output amplifier has an input terminal connected with an output terminal of the preamplifier and an input terminal connected with a reference voltage signal, wherein the output amplifier is configured to output an overpressure signal to an input terminal of an overpressure and overtime control circuit based in part on a comparison between a signal received from the output terminal of the preamplifier and the reference voltage signal.