An AGC-PI Based Readout Circuit for Resonant Pressure Microsensor

This paper presents a readout circuit based on AGC-PI structure for resonant pressure microsensors. A Gm-C based PI controller, which consists of an operational trans-conductance amplifier and a resistor-capacitor network, realizes the proportional-integral control and error amplification. An MOS resistor divider is used as VGA for its simple structure and low flicker noise. The readout circuit is fabricated in a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$0.18\mu\mathrm{m}$</tex> BCD process. Experiments show that the system can operate at temperatures from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-55\sim 85^{\mathrm{o}}\mathrm{C}$</tex> and supply voltages from <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$4\sim 5.5\mathrm{V}$</tex> with a bias instability of 0. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$024\text{Hz}$</tex> and a phase noise of -100dBc/Hz. The current consumption is 2. <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$7\text{mA}$</tex> at <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$5\mathrm{V}$</tex> supply voltage.