# US 12,603,656 B2 · Phase interpolator circuitry with post-distortion linearization

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- Number: US 12,603,656 B2
- Document ID: US12603656B2
- Status: Granted
- Kind: B2
- Application number: 18/426,208
- Filed: 2024-01-29
- Published: 2025-07-31
- Granted: 2026-04-14
- Earliest claimed: 2024-01-29
- Assignees: Apple Inc.
- Applicants: Apple Inc.
- Inventors: Bo Sun; Brian S Leibowitz; Sanjeev K Maheshwari; Jafar Savoj
- Web page: https://patentgrep.com/patent/US12603656B2

## CPC

- H03K 5/131: Digitally controlled
- H03L 7/0998: {using phase interpolation}
- H03L 7/0818: {the controlled phase shifter comprising coarse and fine delay or phase-shifting means}
- H03L 7/083: the reference signal being additionally directly applied to the generator
- 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

The current disclosure is directed to a phase interpolator (PI) with phase correction circuitry. The phase interpolator may generate a clock signal with a phase value. The phase correction circuitry may adjust the phase value of the clock signal to compensate for at least a portion of the undesired distortions. The phase correction circuitry may store pre-determined delay values to at least partially compensate for the undesired distortions of the clock signal based on the control signals. The phase correction circuitry may output the clock signal, as adjusted, with improved phase value accuracy and/or clock signal linearity. In some cases, the phase correction circuitry may improve operations of the phase interpolator, or an electronic system including the phase interpolator, across variations in process, voltage, and/or temperature.

## Claims

### Claim 1

A clock circuit comprising:
a phase interpolator configured to generate an output clock signal based on control signals;
a programmable clock skew circuit coupled to the phase interpolator, wherein the programmable clock skew circuit is configured to adjust the output clock signal based on a delay value to compensate for at least a portion of a distortion of the output clock signal, and wherein the programmable clock skew circuit is configured to output the output clock signal, as adjusted, with a desired phase value; and
a storage device configured to store a lookup table comprising a plurality of delay values, wherein each delay value of the plurality of delay values is associated with a respective desired phase value, and wherein the storage device is configured to output an indication of the delay value of the plurality of delay values to the programmable clock skew circuit based on the control signals.

### Claim 2 (depends on 1)

The clock circuit of claim 1, wherein the control signals are indicative of the desired phase value of the output clock signal.

### Claim 3 (depends on 1)

The clock circuit of claim 1, wherein the phase interpolator is configured to receive a plurality of reference clock signals.

### Claim 4 (depends on 3)

The clock circuit of claim 3, wherein the control signals are indicative of a selection, a weighting factor, or both, associated with each reference clock signal of a subset of the plurality of reference clock signals, wherein the phase interpolator is configured to combine the subset of the plurality of reference clock signals based on the respective selections, the respective weighting factors, or both.

### Claim 5 (depends on 3)

The clock circuit of claim 3, wherein the plurality of reference clock signals comprise an input in-phase clock signal, an input quadrature-phase clock signal, an input negative in-phase clock signal, and an input negative quadrature-phase clock signal.

### Claim 6 (depends on 5)

The clock circuit of claim 5, wherein the input in-phase clock signal is associated with 0° based on a reference phase value, the input quadrature-phase clock signal is associated with 90° based on the reference phase value, the input negative in-phase clock signal is associated with 180° based on the reference phase value, and the input negative quadrature-phase clock signal is associated with 270° based on the reference phase value.

### Claim 7 (depends on 1)

The clock circuit of claim 1, comprising a buffer coupled to the phase interpolator and the programmable clock skew circuit.

### Claim 8 (depends on 1)

The clock circuit of claim 1, wherein the programmable clock skew circuit comprises one or more programmable capacitors, wherein the one or more programmable capacitors are configured to adjust the output clock signal based on the delay value, wherein a capacitance value of the one or more programmable capacitors is configured to correspond to the delay value, wherein the storage device is configured to adjust a capacitance value of at least one of the one or more programmable capacitors by outputting the indication of the delay value.

### Claim 9 (depends on 1)

The clock circuit of claim 1, wherein the delay value is associated with correcting a phase difference between the desired phase value and a phase of the output clock signal generated by the phase interpolator.

### Claim 10

An electronic device comprising:
a processor core complex configured to generate first control signals, wherein the first control signals are indicative of a first desired phase value of an output clock signal; and
a clock circuit coupled to the processor core complex, comprising:
a phase interpolator configured to generate the output clock signal based on the first control signals; and
a programmable clock skew circuit coupled to the phase interpolator, wherein the programmable clock skew circuit comprises one or more programmable capacitors, the one or more programmable capacitors being configured to adjust a phase of the output clock signal based on a first delay value to compensate for at least a portion of a distortion of the output clock signal, wherein the first delay value corresponds to a first capacitance value of at least one of the one or more programmable capacitors, and wherein the programmable clock skew circuit is configured to output the output clock signal, as adjusted, with the first desired phase value.

### Claim 11 (depends on 10)

The electronic device of claim 10, wherein the phase interpolator is configured to receive a plurality of reference clock signals, wherein the first control signals are indicative of a selection, a weighting factor, or both, associated with each reference clock signal of a subset of the plurality of reference clock signals, wherein the phase interpolator is configured to combine the subset of the plurality of reference clock signals based on the respective selections, the respective weighting factors, or both.

### Claim 12 (depends on 10)

The electronic device of claim 10, wherein the clock circuit comprises a storage device configured to store a plurality of delay values, wherein the storage device is configured to output an indication of the first delay value of the plurality of delay values to the programmable clock skew circuit based on the first control signals.

### Claim 13 (depends on 12)

The electronic device of claim 12, wherein the storage device is configured to store a lookup table comprising the plurality of delay values, wherein the first control signals correspond to the first delay value of the plurality of delay values, wherein the storage device is configured to adjust a capacitance value of at least one of the one or more programmable capacitors by outputting the indication of the first delay value.

### Claim 14 (depends on 12)

The electronic device of claim 12, wherein the processor core complex is configured to generate second control signals indicative of a second desired phase value of the output clock signal, wherein the one or more programmable capacitors are configured to adjust the phase of the output clock signal based on a second delay value, wherein the programmable clock skew circuit is configured to output the output clock signal, as adjusted, with the second desired phase value, and wherein the storage device is configured to output an indication of the second delay value of the plurality of delay values to the programmable clock skew circuit based on the second control signals.

### Claim 15

Tangible, non-transitory, computer-readable media storing instructions that, when executed by processing circuitry, cause the processing circuitry to:
receive a plurality of reference clock signals;
receive control signals indicative of a desired phase value of an output clock signal;
generate the output clock signal by combining a subset of the plurality of reference clock signals based on the control signals;
determine a delay value based on the control signals via a lookup table comprising a plurality of delay values;
adjust a phase value of the output clock signal based on the delay value to compensate for at least a portion of a distortion of the output clock signal; and
output the output clock signal, as adjusted, with the desired phase value.

### Claim 16 (depends on 15)

The tangible, non-transitory, computer-readable media of claim 15, wherein the instructions cause the processing circuitry to adjust a capacitance value of a programmable clock skew circuit based on the delay value, and to adjust the phase value of the output clock signal based on the capacitance value of the programmable clock skew circuit.

### Claim 17 (depends on 16)

The tangible, non-transitory, computer-readable media of claim 16, wherein the capacitance value of the programmable clock skew circuit, as adjusted, corresponds to the delay value.

### Claim 18 (depends on 15)

The tangible, non-transitory, computer-readable media of claim 15, wherein the delay value is associated with correcting a phase difference between the desired phase value and a phase of the output clock signal generated by a phase interpolator.

### Claim 19 (depends on 15)

The tangible, non-transitory, computer-readable media of claim 15, wherein the control signals are indicative of a selection, a weighting factor, or both, associated with each reference clock signal of the subset of the plurality of reference clock signals, wherein the instructions cause the processing circuitry to combine the subset of the plurality of reference clock signals based on the respective selections, the respective weighting factors, or both.

### Claim 20 (depends on 15)

The tangible, non-transitory, computer-readable media of claim 15, wherein the plurality of reference clock signals comprise an input in-phase clock signal, an input quadrature- phase clock signal, an input negative in-phase clock signal, and an input negative quadrature-phase clock signal.