# US 10,873,292 B2 · Relaxation oscillators with delay compensation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,873,292 B2 - Document ID: US10873292B2 - Status: Granted - Kind: B2 - Application number: 16/677,406 - Filed: 2019-11-07 - Published: 2020-06-11 - Granted: 2020-12-22 - Earliest claimed: 2018-12-11 - Assignees: Analog Devices International Unlimited Company - Applicants: Analog Devices International Unlimited Company - Inventors: Issa Niakate - Web page: https://patentgrep.com/patent/US10873292B2 ## CPC - H03B 5/24: active element in amplifier being semiconductor device (H03B5/26 takes precedence) - H03K 3/011: Modifications of generator to compensate for variations in physical values, e.g. voltage, temperature {(to maintain energy constant H03K3/015)} - H03B 5/04: Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature - H03K 3/0231: Astable circuits {(H03K3/0315 takes precedence)} - H03L 1/02: against variations of temperature only - H03B: GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS (generators adapted for electrophonic musical instruments G10H; masers or lasers H01S; generation of oscillations in plasma H05H) - H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M) - H03L: AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES (generation of oscillations H03B) ## Abstract Relaxation oscillators with delay compensation are provided herein. In certain embodiments, a relaxation oscillator includes a capacitor, a current source that outputs a charging current, and control circuitry that operates to selectively charge the capacitor with the charging current. The control circuitry includes a primary or main comparator operable to compare a charging voltage of the capacitor to a threshold voltage. The relaxation oscillator further includes delay compensation circuitry coupled to the capacitor and operable to adjust the threshold voltage to provide compensation for a delay of the control circuitry. ## Claims ### Claim 1 A relaxation oscillator with delay compensation, the relaxation oscillator comprising: a first capacitor; a first current source configured to output a first charging current, wherein the first current source is regulated by a feedback loop; control circuitry that operates to selectively charge the first capacitor with the first charging current, the control circuitry including a first primary comparator configured to compare a charging voltage of the first capacitor to a threshold voltage, wherein the threshold voltage is generated based on a feedback voltage of the feedback loop; and delay compensation circuitry electrically coupled to the first capacitor and operable to adjust the threshold voltage to provide compensation for a delay of the control circuitry. ### Claim 2 (depends on 1) The relaxation oscillator of claim 1, further comprising a multiplexer configured to receive a plurality of available threshold voltages, and to output a particular one of the available threshold voltages as the threshold voltage, wherein the delay compensation circuitry controls the multiplexer. ### Claim 3 (depends on 2) The relaxation oscillator of claim 2, wherein the plurality of available threshold voltages are generated based on the feedback voltage of the feedback loop. ### Claim 4 (depends on 3) The relaxation oscillator of claim 3, further comprising a plurality of resistors in series between the feedback voltage and a ground voltage and operable to generate the plurality of available threshold voltages. ### Claim 5 (depends on 1) The relaxation oscillator of claim 1, further comprising a second capacitor, wherein the control circuitry further includes a second primary comparator configured to receive a charging voltage of the second capacitor. ### Claim 6 (depends on 5) The relaxation oscillator of claim 5, wherein the first primary comparator and the second primary comparator both use the threshold voltage for comparisons. ### Claim 7 (depends on 5) The relaxation oscillator of claim 5, wherein the first primary comparator and the second primary comparator use different threshold voltages for comparisons. ### Claim 8 (depends on 7) The relaxation oscillator of claim 7, wherein the delay compensation circuit is operable to separately control the voltage levels of the different threshold voltages. ### Claim 9 (depends on 5) The relaxation oscillator of claim 5, wherein the delay compensation circuitry includes a first secondary comparator configured to receive the charging voltage of the first capacitor, and a second secondary comparator configured to receive the charging voltage of the second capacitor. ### Claim 10 (depends on 9) The relaxation oscillator of claim 9, wherein the first secondary comparator and the second secondary comparator use the feedback voltage of the feedback loop for comparisons. ### Claim 11 (depends on 1) The relaxation oscillator of claim 1, further comprising a reset switch controlled by the control circuitry and operable to reset the charging voltage. ### Claim 12 (depends on 1) The relaxation oscillator of claim 1, further comprising a second capacitor and a second current source configured to generate a second charging current, wherein the control circuitry operates to selectively charge the second capacitor with the second charging current. ### Claim 13 (depends on 1) The relaxation oscillator of claim 1, further comprising a current control switch electrically connected in series with the first current source and the first capacitor and controlled by the control circuitry. ### Claim 14 (depends on 1) The relaxation oscillator of claim 1, wherein a bandwidth and a duty cycle of the delay compensation circuitry are programmable. ### Claim 15 A method of delay compensation in a relaxation oscillator, the method comprising: outputting a charging current from a current source; regulating the current source using a feedback loop; selectively charging a capacitor with the charging current to control a period of the relaxation oscillator using control circuitry; comparing a charging voltage of the capacitor to a threshold voltage using a primary comparator of the control circuitry; generating the threshold voltage based on a feedback voltage of the feedback loop; and adjusting the threshold voltage to provide compensation for a delay of the control circuitry. ### Claim 16 (depends on 15) The method of claim 15, wherein adjusting the threshold voltage to provide compensation includes providing the charging voltage to a secondary comparator. ### Claim 17 (depends on 15) The method of claim 15, wherein adjusting the threshold voltage to provide compensation includes using a multiplexer to select one of a plurality of available threshold voltages as the threshold voltage. ### Claim 18 (depends on 17) The method of claim 17, further comprising generating the plurality of available threshold voltages based on the feedback voltage of the feedback loop. ### Claim 19 (depends on 18) The method of claim 18, further comprising generating the plurality of available threshold voltages using a plurality of resistors in series between the feedback voltage and a ground voltage. ### Claim 20 A method of delay compensation in a relaxation oscillator, the method comprising: outputting a charging current from a current source; selectively charging a capacitor with the charging current to control a period of the relaxation oscillator using control circuitry; comparing a charging voltage of the capacitor to a threshold voltage using a primary comparator of the control circuitry; adjusting the threshold voltage to provide compensation for a delay of the control circuitry, including providing the charging voltage to a secondary comparator; and regulating the charging current using a feedback loop, and using the secondary comparator to compare a feedback voltage of the feedback loop to the charging voltage.