Nxp Usa, Inc.

Freescale Semiconductor,inc.

Hao Zhi

Liang Zhang

Jianzhou Wu

Jie Jin

Zhengxiang Wang

Yizhong Zhang

Yang Wang

Yan Huang

A relaxation oscillator for generating a low temperature coefficient (LTC) clock signal includes a reference voltage generator and an oscillator. The reference voltage generator generates an LTC current and a bandgap reference voltage. The reference voltage generator includes positive temperature coefficient (PTC) resistors to compensate for the effects of temperature variations. The oscillator receives the LTC current and the bandgap reference voltage, and generates a clock signal. In another embodiment, the reference voltage generator generates a charge current that varies with temperature. The oscillator receives the charge current and generates first and second output signals. Set and reset comparators include PTC resistors that determine the gains of the set and reset comparators. The PTC resistors compensate for variation in the first and second output signals due to the temperature variations by varying the gains of the set and reset comparators.

Low temperature coefficient clock signal generator

A rail-to-rail comparator circuit includes NMOS and PMOS differential input stages with associated loads that are coupled to a shared-load stage. The shared-load stage is coupled to an output stage that includes two active devices. By sharing the load stage between the two input stages, the comparator has a relatively small circuit area, low power draw, and low propagation delay with rail-to-rail input common-mode voltage range.

Rail-to-rail comparator with shared active load

A low voltage ripple charge pump with slew rate control includes a frequency divider, a clock generator, a current mirror, a switching circuit, a diode network, two capacitors, and a comparator. The frequency divider generates a clock signal from an oscillating signal. The clock generator generates first and second clock signals from the clock signal. The current mirror generates first and second current signals using a reference current. The switching circuit generates first and second voltage signals using the first and second clock signals and the first and second current signals. The comparator generates the oscillating signal based on the first and second voltage signals. The capacitors receive the voltage signals and are connected to the diode network for generating an output signal. The charge pump has low output voltage ripple with small filtering capacitance, which is achieved via slew rate control.

Low voltage ripple charge pump with shared capacitor oscillator

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Suzhou, China

Hao Zhi