# US 12,603,644 B2 · Methods and apparatus to determine a frequency of a signal

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- Number: US 12,603,644 B2
- Document ID: US12603644B2
- Status: Granted
- Kind: B2
- Application number: 18/525,334
- Filed: 2023-11-30
- Published: 2025-06-05
- Granted: 2026-04-14
- Earliest claimed: 2023-11-30
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Rohit Chatterjee; Atul Ramakant Lele
- Web page: https://patentgrep.com/patent/US12603644B2

## CPC

- H03K 5/24: the characteristic being amplitude
- G06F 1/08: Clock generators with changeable or programmable clock frequency
- H03K 21/02: Input circuits
- 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)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

An example apparatus includes: comparison circuitry configured to determine first and second frequencies from a plurality of clock count ranges and a clock count value, the plurality of clock count ranges each having a range of possible count values corresponding to possible frequencies, the first and second frequencies correspond to the clock count ranges that include the clock count value; comparator circuitry configured to generate a temperature indication based on a comparison of a temperature voltage to a reference temperature voltage; and overlap determination circuitry configured to select one of the first or second frequencies based on the comparator circuitry.

## Claims

### Claim 1

An apparatus comprising:
comparator circuitry configurable to compare a first voltage to a second voltage, wherein the first voltage represents a temperature, and the second voltage represents a reference temperature;
a first clock circuit configurable to produce a first clock signal;
a second clock circuit configurable to produce a second clock signal;
counter circuitry configurable to determine a clock count value based on the first clock signal and the second clock signal;
comparison circuitry configurable to determine a set of frequencies associated with the first clock signal based the clock count value; and
overlap determination circuitry configurable to select a frequency of the set of frequencies based on the comparator circuitry.

### Claim 2 (depends on 1)

The apparatus of claim 1, further comprising temperature sensing circuitry configurable to determine the first voltage as a voltage characteristic of a thermal bipolar junction transistor, the first voltage represents a temperature of the apparatus.

### Claim 3 (depends on 1)

The apparatus of claim 1, wherein the counter circuitry is configurable to generate the clock count value by counting cycles of the first clock signal for a number of cycles of the second clock signal.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein the set of frequencies are of a plurality of possible frequencies each defined by a clock count range, the clock count range specifies a minimum possible count, a maximum possible count, and a frequency of the clock count range, the minimum possible count represents a minimum value of the clock count value that corresponds to the frequency, the maximum possible count represents a maximum value of the clock count value that corresponds to the frequency, the set of frequencies having overlapping clock count ranges.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein the overlap determination circuitry is further configurable to determine the selected frequency responsive to the comparison of the first voltage to the second voltage.

### Claim 6 (depends on 1)

The apparatus of claim 1, further comprising the first clock circuit, wherein the first clock circuit includes external crystal (XTAL) oscillator circuitry coupled to the counter circuitry, the XTAL oscillator circuitry configurable to generate the first clock signal of a frequency greater than the second clock signal.

### Claim 7

A device comprising:
comparison circuitry configurable to determine frequencies based on clock count ranges and a clock count value, the clock count ranges each having a range of count values corresponding to respective frequencies, the frequencies corresponding to the clock count ranges that include the clock count value;
comparator circuitry configurable to generate a temperature indication based on a comparison of a temperature voltage to a reference voltage; and
overlap determination circuitry configurable to select a frequency of the frequencies based on the temperature indication.

### Claim 8 (depends on 7)

The device of claim 7, further comprising temperature sensing circuitry configurable to determine the temperature voltage as a voltage characteristic of a thermal bipolar junction transistor, the temperature voltage represents a temperature of the device.

### Claim 9 (depends on 7)

The device of claim 7, further comprising low frequency oscillator (LFOSC) circuitry configurable to generate a clock signal using an NWELL resistor and a capacitor.

### Claim 10 (depends on 9)

The device of claim 9, wherein the clock signal of the LFOSC circuitry is a first clock signal, the device further comprising counter circuitry configurable to determine the clock count value, the clock count value represents a count of a number of cycles of a second clock signal in a plurality of cycles of the first clock signal.

### Claim 11 (depends on 7)

The device of claim 7, wherein the frequencies are of a plurality of possible frequencies each defined by one of the clock count ranges, each of the clock count ranges including data to determine a minimum count, a maximum count, and a frequency of a clock count range, the minimum count represents a minimum value of the clock count value that corresponds to the frequency, the maximum count represents a maximum value of the clock count value that corresponds to the frequency.

### Claim 12 (depends on 7)

The device of claim 7, wherein the overlap determination circuitry is further configurable to determine the selected frequency to be a frequency of an oscillator clock signal responsive to the temperature indication of the comparator circuitry.

### Claim 13 (depends on 7)

The device of claim 7, further comprising external crystal (XTAL) oscillator circuitry configurable to generate a first clock signal of a frequency greater than a second clock signal from low frequency oscillator (LFOSC) circuitry.

### Claim 14

A method comprising:
counting a number of cycles of a first clock signal for a number of cycles of a second clock signal;
comparing the number of cycles of the first clock signal to a plurality of clock count ranges;
determining a set of frequencies of the clock count ranges that includes the number of cycles of the first clock signal; and
selecting a first frequency of the set of frequencies based on a temperature of a device.

### Claim 15 (depends on 14)

The method of claim 14, wherein the first clock signal is from external crystal (XTAL) oscillator circuitry and the second clock signal is from low frequency oscillator (LFOSC) circuitry, a frequency of the first clock signal is greater than a frequency of the second clock signal.

### Claim 16 (depends on 14)

The method of claim 14, further comprising comparing a temperature voltage to a reference temperature voltage to select the first frequency, the temperature voltage represents the temperature of the device and the reference temperature voltage represents a reference temperature.

### Claim 17 (depends on 14)

The method of claim 14, further comprising generating a temperature voltage using temperature dependent characteristics of a bipolar junction transistor, the temperature voltage representing a temperature of a device.

### Claim 18 (depends on 14)

The method of claim 14, further comprising:
generating a first voltage that represents the temperature of the device; and
comparing the first voltage to a second voltage to determine whether the temperature of the device is greater than or less than a threshold temperature of the second voltage.

### Claim 19 (depends on 14)

The method of claim 14, further comprising determining the first clock signal has a frequency of forty-eight megahertz (MHz) or forty megahertz based on the temperature of the device.