Oscillator devices and methods thereof
AssigneeFreescale Semiconductor, Inc.
InventorsAlfredo Olmos, Jefferson Daniel De Barros Soldera, Gang Qian, Michael Todd Berens
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Abstract
Oscillator devices and methods of operating such oscillator devices are disclosed. The oscillator devices include a current source, and an oscillation module to provide a clock signal. The frequency of the clock signal depends on the relationship between a threshold voltage of a transistor at the oscillation module and the current level provided by the current source. The transistor at the oscillation module is matched to a transistor at the current source so that the frequency of the clock signal is relatively insensitive to changes in device temperature.
Claims14
A method comprising:
- applying a first current to charge a capacitor to a first voltage level during a first interval, the first voltage level dependent on a first threshold voltage;
- generating a first clock signal interval in response to the capacitor charge reaching the first threshold voltage;
- reversing a polarity of the capacitor in response to the capacitor charge reaching the first threshold voltage during the first interval;
- applying the first current to charge the capacitor to a second voltage level during a second interval, the second voltage level dependent on a second threshold voltage;
- and
- generating a second clock signal interval in response to the capacitor charge reaching the second threshold voltage.
A device, comprising
- a current source comprising:
- a first transistor comprising a first current electrode coupled to a first voltage reference, a second current electrode coupled to a second voltage reference, and a control electrode coupled to the second voltage reference;
- a second transistor comprising a first current electrode coupled to the first voltage reference, a second current electrode coupled to the control electrode of the first transistor, and a control electrode coupled to the first current electrode of the first transistor;
- and
- an output coupled to the first current electrode of the first transistor;
- a switching module comprising:
- a capacitor comprising a first current electrode responsive to a voltage at the output of the current source during a first interval and a second current electrode responsive to a voltage at the output of the current source during a second interval;
- and
- a first control module comprising a third transistor that is matched with the first transistor, the third transistor comprising a first current electrode coupled to the first voltage reference, a second current electrode coupled to the second voltage reference, and a control electrode coupled to the first current electrode of the capacitor;
- a second control module comprising a fourth transistor that is matched with the first transistor, the fourth transistor comprising a first current electrode coupled to the first voltage reference, a second current electrode coupled to the second voltage reference, and a control electrode coupled to the second current electrode of the capacitor;
- and
- a latch comprising a first input coupled to the first current electrode of the third transistor, a second input coupled to the first current electrode of the fourth transistor, and a first output configured to provide a periodic signal based on a first signal at the first input and a second signal at the second input.
Dependencies are inferred from the claim text.