US 8,575,981 B1 · MEMS-based frequency synthesizers with enhanced temperature compensation

Abstract

A frequency synthesizer is configured to generate a periodic output signal in response to a periodic input signal and a temperature-dependent frequency adjusting control signal. A temperature sensor is provided, which is configured to generate a temperature measurement signal in response to detecting a temperature of at least a portion of the frequency synthesizer. A control circuit is provided, which is configured to generate the temperature-dependent frequency adjusting control signal in response to the temperature measurement signal. This control circuit includes a cascaded arrangement of an oversampled data converter and a multi-stage digital filter, which is configured to generate a plurality of codes from respective ones of the digital filter stages, and a selection circuit, which is configured to use at least first and second ones of the plurality of codes in sequence during first and second consecutive time intervals to generate the temperature-dependent frequency adjusting control signal.

Claims20

Dependent claims

A frequency synthesizer, comprising:

a phase-locked loop (PLL) frequency generator configured to generate a periodic output signal in response to a periodic input signal, said PLL frequency generator comprising a feedback divider responsive to a feedback divider code;
and
a code generation circuit configured to generate the feedback divider code, said code generation circuit comprising:
an analog-to-digital (ADC) converter configured as a cascaded arrangement of a delta-sigma modulator and a multi-stage digital filter configured to generate a corresponding plurality of divider codes from the multiple stages thereof;
and
a selection circuit configured to use a first of the plurality divider codes to generate the feedback divider code when said PLL frequency generator is unlocked and use a second of the plurality of divider codes to generate the feedback divider code when said PLL frequency generator is locked.

3 more elements

Dependencies are inferred from the claim text.

MEMS-based frequency synthesizers with enhanced temperature compensation

Life of this patent

MEMS-based frequency synthesizers with enhanced temperature compensation

Life of this patent

Abstract

Claims20