Silicon Laboratories Inc.

Yunteng Huang

Axel Thomsen

Michael Henderson Perrott

Rex T Baird

Bruno Werner Garlepp

Jerrell P Hein

Ligang Zhang

David R Welland

Timothy Joseph Dupuis

George Tyson Tuttle

Ruifeng Sun

Adam B Eldredge

Sai Chu Wong

Colin Weltin-Wu

Jeffrey Lee Sonntag

Manu Seth

Peter Vancorenland

Scott Willingham

Michael James Mills

Susumu Hara

Riad S Wahby

Gregory Jon Richmond

Zhongda Wang

Derrick Chunkai Wei

Hua Zhu

Anantha Nag Nemmani

Siddharth Sundar

Zhondga Wang

Michael Petrowski, Iii

Techniques for generating a fail safe clock signal improves reliability of one or more output clock signals generated based on one or more input clock signals and an internally generated reference clock signal. By continuously monitoring the frequencies of the one or more input clock signals and reducing or eliminating effects of any static frequency offset between multiple input clock signals, the fail safe clock generator can detect very small relative frequency changes between the inputs or within a particular input. By comparing the input clock frequencies against a reference clock signal frequency over time of a clock signal generated by an internal oscillator, the fail safe clock generator may further detect which one of multiple input clocks has frequency deviation. The fail safe clock generator uses an internal oscillator generating a reference clock signal having a short-term stable frequency.

Fail safe clock buffer and clock generator

A more cost effective wander jitter filter utilizes an excursion detector that receives a timing difference between a first signal and a second signal and supplies a first adjustment amount if a magnitude of the timing difference is above a predetermined threshold and otherwise supplies a second adjustment amount of zero. A summing circuit adjusts a magnitude of the timing difference by the first or second adjustment amount. A loop filter receives the summing circuit output and controls an oscillator. The excursion detector output (first adjustment value or zero according to the magnitude of the timing difference) is low pass filtered and the low pass filtered is reintroduced into the oscillator output or the feedback loop. The excursion detector output is accumulated and used to adjust a phase of the feedback signal from the oscillator.

Dual path timing wander removal

A gap detector detects when a phase difference between a feedback signal and a clock signal is larger than a gap threshold. If the phase difference is larger than the gap threshold, then the phase difference is modified by subtracting a gap value from the phase difference. If the phase difference is less than the threshold, the phase difference is not modified. A loop filter receives and filters the modified or unmodified phase difference and controls an oscillator. An accumulator circuit accumulates the modified phase difference and supplies a phase adjust signal. A low pass filter receives the phase adjust signal and supplies a filtered phase adjust signal that is used to slowly adjust the output of the oscillator.

Dual path timing jitter removal

A micro electro mechanical system (MEMS) oscillator supplies an oscillator output signal having a first frequency that differs from a predetermined frequency of the output signal. An error determination circuit determines frequency error from the predetermined frequency based on initial frequency offset and/or temperature and provides the error information indicating a difference between the first frequency and the predetermined frequency. The error information is used by a receiving system in frequency translation logic that utilizes the oscillator output signal as a frequency reference.

Accurate frequency control using a MEMS-based oscillator

A first integrated circuit die receives input data from a plurality of input channels and combines the input data from the plurality of input channels into combined data. The first integrated circuit die transmits the combined data across an isolation communication channel. A second integrated circuit die that is coupled to the isolation communication channel decodes the transmitted combined data and supplies the decoded transmitted combined data to respective output channels corresponding to the input channels.

Isolated serializer-deserializer

A fractional-N divider supplies a divided clock signal. An adjusted divided clock signal is generated in a digital-to-time converter circuit having a delay linearly proportional to digital quantization errors of the fractional-N divider. The adjusted divided clock signal is generated based on first and second capacitors charging to a predetermined level. The charging of the first and second capacitors is interleaved in alternate periods of the divided clock. The charging of each capacitor with a current corresponding to respective digital quantization errors is interleaved with charging with a fixed current. A first edge of a first pulse of the adjusted divided clock signal is generated in response to the first capacitor charging to a predetermined voltage and a first edge of a next pulse of the adjusted divided clock signal is generated in response to the second capacitor charging to the predetermined voltage.

Time-interleaved digital-to-time converter

A digital frequency synthesizer provides absolute phase lock and shorter settling time through the use of a digital filter with a phase and frequency path. Control logic control disables the frequency path during the frequency acquisition and sets a wide bandwidth. After frequency acquisition, a counter with digital phase information is reset using the input clock signal to bring the output phase closer to lock with the input signal and the control logic enables the phase path in the digital loop filter to achieve phase lock with a narrower bandwidth than the initial bandwidth.

Frequency synthesizer with hit-less transitions between frequency- and phase-locked modes

A transmitter is adapted to be programmed to select an amplifier operating class for the transmitter out of a plurality of amplifier operating classes. The transmitter is also adapted to operate according to the selected amplifier operating class to communicate a signal to an antenna.

Transmitter having a programmable amplifier operating class

A clock synthesis circuit includes a delta sigma modulator that receives a divide ratio and generates an integer portion and a digital quantization error (a fractional portion). A fractional-N divider divides a received signal according to a divide control value corresponding to the integer portion and generates a divided signal. A phase interpolator adjusts a phase of the divided signal according to the digital quantization error to thereby reduce noise associated with the fractional-N divider.

Direct digital interpolative synthesis

A power control circuit is coupled to receive a feedback signal from a power amplifier (PA) and generate a control signal to control a variable gain amplifier (VGA) coupled to an input to the PA based on the feedback signal. The power control circuit may include, in one embodiment, a mute circuit to generate a mute signal to be provided to the VGA when the control signal is less than a first level and a clamp circuit to clamp a control voltage used to generate the control signal from exceeding a threshold level.

Providing automatic power control for a power amplifier

In one form, a power converter for a power detector or the like includes first and third transistors of a first conductivity type, and second and fourth transistors of a second conductivity type. A control electrode of the first transistor receives a first bias voltage plus a positive component of a differential input signal. The second transistor is coupled in series with the first transistor and has a control electrode receiving a second bias voltage plus a negative component of the differential input signal. The third transistor is biased using the first bias voltage plus the negative component. The fourth transistor is coupled in series with the third transistor and is biased using the second bias voltage plus the positive component. A common interconnection point of the first and third transistors forms an output node.

Radio frequency (RF) power detector suitable for use in automatic gain control (AGC)

In one form, a power detector includes first and third transistors of a first conductivity type, and second and fourth transistors of a second conductivity type. A control electrode of the first transistor receives a first bias voltage plus a positive component of a differential input signal. The second transistor is coupled in series with the first transistor and has a control electrode receiving a second bias voltage plus a negative component of the differential input signal. The third transistor is biased using the first bias voltage plus the negative component. The fourth transistor is coupled in series with the third transistor and is biased using the second bias voltage plus the positive component. A common interconnection point of the first and third transistors forms an output node. In another form, a power detector compares an output of a power detector core to multiple threshold voltages in corresponding comparators.

A first phase-locked loop (PLL) circuit includes an input for receiving a timing reference signal from an oscillator, a controllable oscillator circuit supplying an oscillator output signal, and a multi-modulus feedback divider circuit. A second control loop circuit is selectably coupled through a select circuit to supply a digital control value (M) to the multi-modulus feedback divider circuit of the first loop circuit to thereby control the oscillator output signal. While the second control loop is coupled to supply the control value to the feedback divider circuit, the control value is determined according to a detected difference between the oscillator output signal and a reference signal coupled to the second control loop circuit at a divider circuit. While the second control loop circuit is not coupled to control the first PLL circuit, the first PLL circuit receives a digital control value to control a divide ratio of the feedback divider, the digital control value is determined at least in part according to a stored control value stored in nonvolatile storage, the stored control value corresponding to a desired frequency of the oscillator output signal.

Dual loop architecture useful for a programmable clock source and clock multiplier applications

A technique for expanding an input signal includes receiving the input signal at a first node of a voltage expander and generating a plurality of expanded signals on different outputs of the voltage expander responsive to the input signal. In certain embodiments, each of the expanded signals has a different magnitude at a respective fixed offset from the input signal.

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Irvine, CA, United States of America

Yunteng Huang