University of Michigan

Seok Hyeon Jeong

David Theodore Blaauw

Dennis Sylvester

Sechang Oh

Kyojin Choo

Rohit Rothe

An amplifier is presented with a sample and average common mode feedback resistor. The amplifier circuit includes a feedback capacitor and a feedback resistor in parallel with the feedback capacitor, where the feedback capacitor and the feedback resistor form part of the negative feedback path for the amplifier. Of note, the feedback resistor is comprised of a low pass filter in series with a switched capacitor resistor, such that the low pass filter is electrically coupled to the output of the amplifier circuit and the switched capacitor resistor is electrically coupled to the inverting input of the amplifier circuit. The amplifier circuit further includes a control circuit interfaced with switches of the switched capacitor resistor. The high pass corner of the switched capacitor resistor is preferably lower than corner of the low pass filter.

Amplifier with sample and average common mode feedback resistor

An ultra-low power oscillator is designed for wake-up timers that can be used in compact wireless sensors, for example. A constant charge subtraction scheme removes continuous comparator delay from the oscillation period, which is the source of temperature dependence in conventional RC relaxation oscillators. This relaxes comparator design constraints, enabling low power operation. In 0.18 &#x3bc;m CMOS, the oscillator consumes 5.8 nW at room temperature with temperature stability of 45 ppm/&#xb0; C. (&#x2212;10&#xb0; C. to 90&#xb0; C.) and 1%/V line sensitivity.

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Ann Arbor, MI, United States of America

Seok Hyeon Jeong