公开(公告)号：US10574185B2

公开(公告)日：2020-02-25

申请号：US15639267

申请日：2017-06-30

Applicant: SILICON LABORATORIES INC.

Inventor： Tiago Marques ,  John Khoury

IPC: H03B5/36 ,  H03B5/04

Abstract: A crystal driver circuit for driving a crystal to oscillate at a resonant frequency including an amplifier having an input coupled to an amplifier input node and having an output coupled to an amplifier output node, a current source that provides a core bias current to the amplifier, a first tune capacitor coupled between the amplifier output node and a reference node, and a second tune capacitor coupled between the amplifier input node and the reference node. The first tune capacitor has a first capacitance that is greater than a second capacitance of the second tune capacitor by a capacitance offset that reduces frequency shift during operation. The first and second capacitances have a combined capacitance that achieves an oscillating signal having a target frequency.

公开(公告)号：US10367462B2

公开(公告)日：2019-07-30

申请号：US15639038

申请日：2017-06-30

Applicant: SILICON LABORATORIES INC.

Inventor： Tiago Marques

IPC: H03B5/06 ,  H03B5/36 ,  H03L3/00 ,  H03L5/02 ,  H03F3/45 ,  H03F3/16 ,  H01L27/07 ,  H03F3/193

Abstract: A crystal amplifier for driving a crystal to oscillate at a resonant frequency including a controlled current source, a primary amplifier core, a high gain amplifier core, and a controller. Both amplifier cores are coupled in parallel, and each has an input coupled to an amplifier input node and an output coupled to an amplifier output node coupled across the crystal. The current source provides a core bias current to the source node. The controller enables the high gain amplifier core and sets the core bias current to a high current level to achieve a high negative resistance at a startup time, and then disables the high gain amplifier core and sets the core bias current to a lower steady state current level after oscillation is achieved. A level detector may be used for detecting oscillation and for determining when to adjust the core bias current.

公开(公告)号：US10601369B2

公开(公告)日：2020-03-24

申请号：US16032348

申请日：2018-07-11

Applicant: SILICON LABORATORIES INC.

Inventor： Tiago Marques ,  Chester Yu

IPC: H03B5/06 ,  H03L3/00 ,  H03B5/36

Abstract: An oscillation circuit including a crystal interface, a crystal amplifier, a level detector, a timing circuit, and a controller. When activated, the crystal amplifier drives a crystal coupled to the crystal interface to establish oscillation, and the level detector indicates when a target amplitude is detected. The controller activates the crystal amplifier and uses the timing circuit and the level detector to measure a startup time of oscillation. The measured startup time is used in calculating a wake up time from a sleep mode in time to perform an operation at a scheduled time. The startup time may be adjusted or averaged and may be remeasured with temperature change. A method of minimizing startup time of a crystal oscillator includes measuring startup time for determining a delay value for programming a wakeup circuit. Robust startup settings may be used in the event of startup failure due to a sleepy crystal.

公开(公告)号：US10536115B2

公开(公告)日：2020-01-14

申请号：US15724714

申请日：2017-10-04

Applicant: SILICON LABORATORIES INC.

Inventor： Tiago Marques ,  Vitor Pereira

IPC: H03B5/36 ,  H03F3/72

Abstract: A crystal driver integrated circuit with external oscillation signal amplitude control including an amplifier core, an input pin and an output pin, an adjustable capacitor, and a controller. The controller operates the amplifier core in any one of multiple operating modes including an oscillator mode and a bypass mode. During the bypass mode, the controller disables the amplifier core and adjusts the adjustable capacitor so that an amplitude of an oscillation signal received via the input pin from an external oscillator has a target amplitude. The external oscillation signal may be capacitively coupled for capacitive voltage division or directly coupled for impedance attenuation. An available voltage may be provided as a source voltage to the external oscillator via the output pin. An internal voltage regulator and/or switch may be included to re-provision the output pin to provide the source voltage during the bypass mode.

公开(公告)号：US10454420B2

公开(公告)日：2019-10-22

申请号：US15645684

申请日：2017-07-10

Applicant: SILICON LABORATORIES INC.

Inventor： Tiago Marques

IPC: H03B5/36 ,  H03F3/72

Abstract: A crystal driver integrated circuit configurable for daisy chaining including an amplifier core, an input pin and an output pin, and a controller that operates the amplifier core in any one of multiple operating modes. The operating modes include an oscillator mode for driving an external crystal coupled between the input and output pins to generate an oscillation signal at a target frequency, and an amplifier mode that amplifies an external oscillating signal provided to the input pin to provide an amplified oscillation signal on the output pin. The amplifier core includes a controllable current source that provides a core bias current to an amplifier having a level that is adjusted depending upon the operating mode and desired amplitude. The operating modes may include a bypass mode in which the amplifier core is disabled. The amplifier may be implemented as either an PMOS amplifier or an NMOS amplifier.