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US 6,784,755 B2Granted
Compact, high power supply rejection ratio, low power semiconductor digitally controlled oscillator architecture
AssigneeTexas Instruments Incorporated
InventorsHeng-Chih Lin, Baher S. Haroun
Life of this patent
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Abstract
A high PSRR, low power semiconductor digitally controlled oscillator (DCO) architecture employs only one simple current steering D/A converter directly on top of a multi-stage current controlled oscillator. The architecture provides a good building block for many circuit applications, e.g., all digital phase lock loops, direct modulation transmitters for wireless devices, and the like.
Claims10
A digitally controlled oscillator (DCO) comprising:
- a current controlled oscillator;
- a current source configured to provide a bias current for the current controlled oscillator;
- and
- no more than one current steering digital-to-analog converter (DAC) directly on top of the current controlled oscillator, wherein the DAC is configured to selectively steer a tuning current provided by the DAC into the current controlled oscillator to control the frequency of oscillation provided by the current controlled oscillator,
- wherein the current controlled oscillator comprises a multi-stage digitally controlled oscillator (DCO) and the multi-stage DCO comprises at least one delay stage including a current controlled negative MOS resistance operational to tune the frequency of oscillation in response to the tuning current.
2 more elements
A digitally controlled oscillator (DCO) comprising:
- a multi-stage current controlled oscillator;
- a current source directly on top of the current controlled oscillator and configured to provide a bias current for the current controlled oscillator;
- and
- at least one current steering digital-to-analog converter (DAC) directly on top of the current controlled oscillator and configured to generate and steer a tuning current into the current controlled oscillator to control its frequency of oscillation,
- wherein at least one stage of the multi-stage current controlled oscillator comprises a delay element and the delay element comprises a current controlled negative MOS resistance operational to tune the frequency of oscillation in response to the tuning current.
2 more elements
A method of controlling an oscillation frequency, the method comprising the steps of:
- providing a high PSRR, low power semiconductor digitally controlled oscillator (DCO) that employs only one simple current steering D/A converter directly on top of a multi-stage current controlled oscillator;
- and
- generating and steering a current into the multi-stage current controlled oscillator via the D/A converter to control the frequency of oscillation,
- wherein the step of generating and steering a current into the multi-stage current controlled oscillator via the D/A converter to control the frequency of oscillation comprises passing the steering current through a current controlled negative MOS resistance operational to tune the frequency of oscillation in response to the tuning current.
1 more element
Dependencies are inferred from the claim text.