JP-7857388-B2 - Control and calibration of external oscillators

Inventors

• ハイマン・シャナン
• ジョン・ケニー

Assignees

• アナログ ディヴァイスィズ インク

Dates

Publication Date

20260512

Application Date

20241219

Priority Date

20201208

Claims (18)

1. An electronic oscillator system, Semiconductor die and A controllable oscillator located outside the semiconductor die, A first varactor configured to adjust the oscillation frequency of the controllable oscillator, The controllable oscillator comprises a second varactor configured to adjust the oscillation frequency of the controllable oscillator, The semiconductor die comprises a phase-locked loop (PLL) configured to provide fine adjustment to the controllable oscillator by controlling the first varactor, a calibration circuit configured to provide coarse adjustment to the controllable oscillator by controlling the second varactor, a coarse adjustment voltage pin configured to output a coarse control voltage from the calibration circuit, a calibration digital-to-analog converter (DAC) , and a calibration charge pump, wherein the calibration circuit operates in a first mode in which the calibration DAC sets the voltage level of the coarse adjustment voltage pin, and a second mode in which the calibration charge pump sets the voltage level of the coarse control voltage , in an electronic oscillator system.
2. The electronic oscillator system according to claim 1, further comprising a coarse-tuned voltage scaling circuit configured to scale the coarse-tuned voltage to generate a varactor-tuned voltage for the second varactor.
3. The electronic oscillator system according to claim 1, wherein the semiconductor die further comprises a first transconductance stage and a second transconductance stage, wherein in the first mode, the first transconductance stage and the second transconductance stage operate in series to adjust the voltage level of the coarse adjustment voltage pin after it has been set by the calibration DAC, and in the second mode, the first transconductance stage adjusts the voltage level of the coarse adjustment voltage pin after it has been set by the calibration charge pump.
4. The electronic oscillator system according to claim 3, wherein in the first mode, the first transconductance stage generates a current based on comparing a reference signal with a sensed fine-tuning voltage in order to control the second varactor, and the second transconductance stage receives the current and drives the coarse-tuning voltage pin.
5. The electronic oscillator system according to claim 1, further comprising a digital-to-analog converter (DAC) having an input for receiving digital data from the calibration circuit and an output connected to the coarse adjustment voltage pin, wherein the coarse adjustment voltage pin is for controlling the second varactor.
6. The electronic oscillator system according to claim 1, further comprising: a first DAC for controlling the coarse adjustment voltage pin based on a process voltage-temperature (PVT) code; and a second DAC for controlling the coarse adjustment voltage pin based on an oscillator voltage range sensed by the calibration circuit.
7. The electronic oscillator system according to claim 1, wherein the calibration circuit is configured to calibrate the amplitude of the controllable oscillator based on controlling the bias of the controllable oscillator and observing the output oscillator signal of the controllable oscillator.
8. The electronic oscillator system according to claim 1, wherein the calibration circuit is configured to compare the adjustment voltage set by the PLL with an upper threshold signal and a lower threshold signal.
9. The electronic oscillator system according to claim 8, further comprising: a first comparator for comparing the adjustment voltage with the upper threshold signal; a second comparator for comparing the adjustment voltage with the lower threshold signal; a counter controlled based on the output of the first comparator and the output of the second comparator; and an integrator configured to integrate the output of the counter .
10. The electronic oscillator system according to claim 1, further comprising an external temperature sensor, wherein the calibration circuit operates based on temperature data received from the external temperature sensor.
11. The electronic oscillator system according to claim 1, wherein the second varactor provides a higher frequency-to-voltage gain than the first varactor.
12. A method for controlling an electronic oscillator, The adjustment involves using a first varactor to adjust the oscillation frequency of a controllable oscillator, wherein the controllable oscillator is located outside the semiconductor die. Adjusting the oscillation frequency of the controllable oscillator using a second varactor, Controlling the first varactor to provide fine-tuning to the controllable oscillator using a phase-locked loop (PLL) on the semiconductor die, The second varactor is controlled to provide coarse adjustment to the controllable oscillator using the calibration circuit of the semiconductor die by outputting a coarse control voltage through the coarse adjustment voltage pin of the semiconductor die, A method comprising operating the semiconductor die in either a first mode in which a calibration DAC sets the voltage level of the coarse adjustment voltage pin, or a second mode in which a calibration charge pump sets the voltage level of the coarse control voltage .
13. The method according to claim 1 or 2, further comprising outputting a coarse control voltage from a coarse adjustment voltage pin of the semiconductor die, and scaling the coarse control voltage using an amplifier to generate a varactor control voltage for the second varactor.
14. The method according to claim 1 or 2, further comprising receiving digital data from the calibration circuit as input to a digital-to-analog converter (DAC ) , and providing a coarse control voltage from the output of the DAC to the coarse adjustment voltage pin of the semiconductor die.
15. The method according to claim 1 or 2 , further comprising comparing the adjustment voltage set by the PLL with an upper threshold signal and a lower threshold signal.
16. A radio frequency communication system, A mixer controlled by an oscillator signal, It is a local oscillator, Semiconductor die, A controllable oscillator located outside the semiconductor die and configured to output the oscillator signal, A local oscillator comprising a first varactor configured to adjust the oscillation frequency of the controllable oscillator, and a second varactor configured to adjust the oscillation frequency of the controllable oscillator, The semiconductor die comprises a phase-locked loop (PLL) configured to provide fine adjustment to the controllable oscillator by controlling the first varactor, a calibration circuit configured to provide coarse adjustment to the controllable oscillator by controlling the second varactor, a coarse adjustment voltage pin configured to output a coarse control voltage from the calibration circuit , a calibration digital-to-analog converter (DAC), and a calibration charge pump , wherein the calibration circuit operates in a first mode in which the calibration DAC sets the voltage level of the coarse adjustment voltage pin, and a second mode in which the calibration charge pump sets the voltage level of the coarse control voltage , in a radio frequency communication system.
17. The radio frequency communication system according to claim 16 , wherein the calibration circuit is configured to compare the adjustment voltage set by the PLL with an upper threshold signal and a lower threshold signal.
18. The radio frequency communication system according to claim 16 , wherein the second varactor provides a higher frequency-to-voltage gain than the first varactor.

Description

Embodiments of the invention relate to electronic systems, and more specifically, to the control and calibration of external oscillators. Voltage-controlled oscillators (VCOs) are widely used in electronic and communication applications such as clock generation and distribution, carrier wave synthesis, and data recovery. A VCO may include an oscillator core that generates an oscillating output signal, and a resonator (e.g., an inductor-capacitor tank) attached to the oscillator core that exhibits variable electrical properties such as capacitance and/or inductance. The oscillation frequency depends at least partially on the value of the variable electrical properties; therefore, adjusting the resonator provides a method for controlling the oscillation frequency of the output signal. A VCO can be included in a control loop such as a phase-locked loop (PLL). Such a control loop can use feedback to set the VCO's input control voltage to a desired value. Apparatus and methods for controlling and calibrating an external oscillator are provided. In a particular embodiment, the electronic oscillator system includes a semiconductor die and a controllable oscillator located outside the semiconductor die. The oscillation frequency of the controllable oscillator is tuned by a first varactor and a second varactor. The semiconductor die includes a phase-locked loop (PLL) that provides fine adjustment to the controllable oscillator by controlling the first varactor, and a calibration circuit that provides coarse adjustment to the controllable oscillator by controlling the second varactor. In one embodiment, the electronic oscillator system includes a semiconductor die, a controllable oscillator located outside the semiconductor die, a first varactor configured to adjust the oscillation frequency of the controllable oscillator, and a second varactor configured to adjust the oscillation frequency of the controllable oscillator. The semiconductor die includes a phase-locked loop (PLL) configured to provide fine adjustment to the controllable oscillator by controlling the first varactor, and a calibration circuit configured to provide coarse adjustment to the controllable oscillator by controlling the second varactor. In another embodiment, a method for controlling an electronic oscillator is provided. The method includes adjusting the oscillation frequency of a controllable oscillator using a first varactor, wherein the controllable oscillator is located outside a semiconductor die. The method further includes adjusting the oscillation frequency of the controllable oscillator using a second varactor, controlling the first varactor to provide fine adjustment to the controllable oscillator using a phase-locked loop (PLL) on the semiconductor die, and controlling the second varactor to provide coarse adjustment to the controllable oscillator using a calibration circuit on the semiconductor die. In another embodiment, a radio frequency communication system is provided. The radio frequency communication system includes a mixer controlled by an oscillator signal, and a local oscillator comprising a semiconductor die, a controllable oscillator located outside the semiconductor die and configured to output the oscillator signal, a first varactor configured to adjust the oscillation frequency of the controllable oscillator, and a second varactor configured to adjust the oscillation frequency of the controllable oscillator. The semiconductor die includes a phase-locked loop (PLL) configured to provide fine adjustment to the controllable oscillator by controlling the first varactor, and a calibration circuit configured to provide coarse adjustment to the controllable oscillator by controlling the second varactor. This is a schematic diagram of one embodiment of a radio frequency (RF) communication system.This is a schematic diagram of one embodiment of adjusting an externally voltage controllable oscillator (VCO).This is a schematic diagram of another example of adjusting an external VCO.This is a schematic diagram of an electronic oscillator system according to one embodiment.This is a schematic diagram of an electronic oscillator system according to another embodiment.This is a schematic diagram of an external VCO tracking loop according to one embodiment.This is a schematic diagram of an external VCO tracking loop according to another embodiment.This is a schematic diagram of an external VCO tracking loop according to another embodiment.This is a schematic diagram of an electronic oscillator system according to another embodiment.This is a schematic diagram of another embodiment of an electronic oscillator system including a semiconductor die operating in a first coarse calibration mode.This is a schematic diagram of another embodiment of an electronic oscillator system including a semiconductor die operating in a second coarse calibration mode. The following detailed description of embodiments presents various descriptions of spec