# US 2023/0055100 A1 · Temperature dependent acceleration current source circuitry

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- Number: US 2023/0055100 A1
- Document ID: US20230055100A1
- Status: Published application
- Kind: A1
- Application number: 17/404,225
- Filed: 2021-08-17
- Published: 2023-02-23
- Earliest claimed: 2021-08-17
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Carsten Ingo Stoerk; Johann Erich Bayer; Ruediger Ganz
- Web page: https://patentgrep.com/patent/US20230055100A1

## CPC

- G01P 1/006: {used for thermal compensation}
- G01K 3/10: in respect of time, e.g. reacting only to a quick change of temperature
- G05F 3/30: Regulators using the difference between the base-emitter voltages of two bipolar transistors operating at different current densities (G05F3/26 takes precedence)
- G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G})
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES

## Abstract

Systems, methods, and circuitries are provided for generating an acceleration current in response to a threshold temperature being reached. In one example, temperature based acceleration current source circuitry includes a first temperature sensitive device, a second temperature sensitive device, differential trigger circuitry, and an acceleration current source. The first temperature sensitive device is configured to generate a first signal that varies responsive to temperature changes at a first rate. The second temperature sensitive device is configured to generate a second signal that varies responsive to temperature changes at a second rate. The differential trigger circuitry is configured to generate a trigger signal based on a difference between the first signal and the second signal. The acceleration current source circuitry is configured to output an acceleration current in response to the trigger signal.

## Claims

### Claim 1

Temperature based acceleration current source circuitry, comprising:
differential trigger circuitry, comprising:
a diode device biased by a first leakage current to generate a bias voltage; and
a trigger device biased by the bias voltage;
a first temperature sensitive device coupled in parallel between the diode device and a common node, wherein the first leakage current flows through the first temperature sensitive device, further wherein the first leakage current varies responsive to temperature at a first rate;
a second temperature sensitive device coupled in parallel between the trigger device and the common node, wherein a second leakage current flows through the second temperature sensitive device, further wherein the second leakage current varies responsive to temperature at a second rate; and
an acceleration current source coupled to the trigger device, wherein the acceleration current source is configured to, in response to activation by the trigger device, conduct an acceleration current generated by a source voltage to an output of the temperature based acceleration current source circuitry,
wherein the trigger device is controlled by a difference between the first leakage current and a second leakage current to selectively activate the acceleration current source.

### Claim 2 (depends on 1)

The temperature based acceleration current source circuitry of claim 1, wherein
the first temperature sensitive device comprises a first plurality of metal oxide semiconductor (MOS) transistors coupled in parallel between the diode device and the common node, wherein a body of each MOS transistor in the first plurality is coupled to the diode device and conducts a respective portion of the first leakage current, further wherein sources of a first number of the MOS transistors in the first plurality are coupled to the diode device and conduct respective portions of the first leakage current while sources of a remainder of the first plurality of MOS transistors are open; and
the second temperature sensitive device comprises a second plurality of MOS transistors coupled in parallel between the trigger device and the common node, further wherein a body of each MOS transistor in the second plurality is coupled to a gate of the trigger device and conducts a respective portion of the second leakage current, wherein sources of a second number of the MOS transistors in the second plurality are coupled to the gate of the trigger device and conduct respective portions of the second leakage current while sources of a remainder of the second plurality of MOS transistors are open.

### Claim 3 (depends on 2)

The temperature based acceleration current source circuitry of claim 2 wherein the first plurality of MOS transistors includes a same number of MOS transistors as the second plurality of MOS transistors and the remainder of the second plurality of MOS transistors includes zero MOS transistors.

### Claim 4 (depends on 1)

The temperature based acceleration current source circuitry of claim 1, wherein the diode device comprises a third plurality of MOS transistors coupled in series, wherein each MOS transistor in the third plurality has a gate coupled to the bias voltage.

### Claim 5 (depends on 4)

The temperature based acceleration current source circuitry of claim 4, wherein the differential trigger circuitry comprises trigger temperature selection circuitry comprising a fourth plurality of transistors, wherein each transistor in the fourth plurality is coupled in parallel with a respective MOS transistor in the third plurality, wherein each transistor in the fourth plurality has a gate coupled to a respective temperature selection input.

### Claim 6 (depends on 1)

The temperature based acceleration current source circuitry of claim 1, wherein the trigger device comprises a MOS transistor is coupled to gates of series-coupled MOS transistors, so that in response to a difference between the first leakage current and the second leakage current reaching a threshold the MOS transistor enters a saturation region of operation and activates the series-coupled MOS transistors.

### Claim 7

A watchdog circuit, comprising:
an integrator circuit configured to generate an output pulse in response to an input voltage exceeding a threshold;
a capacitor coupled in parallel with the integrator circuit, wherein the capacitor is coupled to a proportional to absolute temperature (PTAT) circuit and charged by a current generated by the PTAT circuit, further wherein a voltage across the capacitor corresponds to the input voltage to the integrator circuit; and
temperature based acceleration current source circuitry coupled to the capacitor, wherein an acceleration current output by the temperature based acceleration current source circuitry charges the capacitor, further wherein the temperature based acceleration current source circuitry is configured to selectively output the acceleration current in response to an ambient temperature reaching a target.

### Claim 8 (depends on 7)

The watchdog circuit of claim 7, wherein the temperature based acceleration current source circuitry comprises:
differential trigger circuitry, comprising:
a diode device biased by a first leakage current to generate a bias voltage; and
a trigger device biased by the bias voltage;
a first temperature sensitive device coupled in parallel between the diode device and a common node, wherein the first leakage current flows through the first temperature sensitive device, further wherein the first leakage current varies responsive to temperature changes at a first rate;
a second temperature sensitive device coupled in parallel between the trigger device and the common node, wherein a second leakage current flows through the second temperature sensitive device, further wherein the second leakage current varies responsive to temperature changes at a second rate; and
an acceleration current source coupled to the trigger device, wherein the acceleration current source is configured to, in response to activation by the trigger device, conduct an acceleration current generated by a source voltage to an output of the temperature based acceleration current source circuitry,
wherein the trigger device is controlled by a difference between the first leakage current and a second leakage current to selectively activate the acceleration current source.

### Claim 9 (depends on 8)

The watchdog circuit of claim 8, wherein
the first temperature sensitive device comprises a first plurality of metal oxide semiconductor (MOS) transistors coupled in parallel between the diode device and the common node, wherein a body of each MOS transistor in the first plurality is coupled to the diode device and conducts a respective portion of the first leakage current, further wherein sources of a first number of the MOS transistors in the first plurality are coupled to the diode device and conduct respective portions of the first leakage current while sources of a remainder of the first plurality of MOS transistors are open; and
the second temperature sensitive device comprises a second plurality of MOS transistors coupled in parallel between the trigger device and the common node, further wherein a body of each MOS transistor in the second plurality is coupled to a gate of the trigger device and conducts a respective portion of the second leakage current, wherein sources of a second number of the MOS transistors in the second plurality are coupled to the gate of the trigger device and conduct respective portions of the second leakage current while sources of a remainder of the second plurality of MOS transistors are open.

### Claim 10 (depends on 8)

The watchdog circuit of claim 8, wherein the diode device comprises a third plurality of MOS transistors coupled in series, wherein each MOS transistor in the third plurality has a gate coupled to the bias voltage.

### Claim 11 (depends on 10)

The watchdog circuit of claim 10, wherein the differential trigger circuitry comprises trigger temperature selection circuitry comprising a fourth plurality of transistors, wherein each transistor in the fourth plurality is coupled in parallel with a respective MOS transistor in the third plurality, wherein each transistor in the fourth plurality has a gate coupled to a respective temperature selection input.

### Claim 12 (depends on 8)

The watchdog circuit of claim 8, wherein the trigger device comprises a MOS transistor is coupled to gates of series-coupled MOS transistors, so that in response to a difference between the first leakage current and the second leakage current reaching a threshold the MOS transistor enters a saturation region of operation and activates the series-coupled MOS transistors.

### Claim 13

A method, comprising:
generating a first signal that varies responsive to temperature changes according to a first rate;
generating a second signal that varies responsive to temperature changes according to a second rate;
generating a trigger signal in response to a difference between the first signal and the second signal exceeding a threshold; and
outputting an acceleration current in response to the trigger signal.

### Claim 14 (depends on 13)

The method of claim 13, comprising:
generating the first signal with a first temperature sensitive device that exhibits a first leakage current that varies responsive to temperature changes according to the first rate;
generating the second signal with a second temperature sensitive device that exhibits a second leakage current that varies responsive to temperature changes according to the second rate; and
generating the trigger signal corresponding to a drain current of a trigger MOS transistor having a gate coupled to the first temperature sensitive device and a drain coupled to the second sensitive device, wherein the trigger MOS transistor enters saturation region in response to a difference between the first leakage current and the second leakage current exceeding a threshold.

### Claim 15 (depends on 14)

The method of claim 14, comprising:
generating the first leakage current with a first plurality of metal oxide semiconductor (MOS) transistors, wherein a body of each MOS transistor in the first plurality conducts a respective portion of the first leakage current, further wherein sources of a first number of the MOS transistors in the first plurality conduct respective portions of the first leakage current while sources of a remainder of the first plurality of MOS transistors are open; and
generating the second leakage current with a second plurality of MOS transistors. wherein a body of each MOS transistor in the second plurality conducts a respective portion of the second leakage current, further wherein sources of a second number of the MOS transistors in the second plurality conduct respective portions of the second leakage current while sources of a remainder of the second plurality of MOS transistors are open.

### Claim 16 (depends on 15)

The method of claim 15 wherein a ratio of the first number to the second number is 1 to 6.

### Claim 17 (depends on 14)

The method of claim 14, comprising:
generating a bias voltage with a diode device, wherein the diode device is coupled in series with the first temperature sensitive device and is biased by the first leakage current, further wherein the diode device comprises a third plurality of MOS transistors coupled in series, wherein each MOS transistor in the third plurality has a gate coupled to the bias voltage; and
providing the bias voltage to the gate of trigger MOS transistor.

### Claim 18 (depends on 17)

The method of claim 17, comprising:
adjusting the bias voltage by selectively activating one or more MOS transistors that form shorting paths around respective one or more of the MOS transistors in the third plurality.

### Claim 19

Temperature based acceleration current source circuitry, comprising:
a first temperature sensitive device configured to generate a first signal that varies responsive to temperature changes at a first rate;
a second temperature sensitive device configured to generate a second signal that varies responsive to temperature changes at a second rate;
differential trigger circuitry configured to generate a trigger signal based on a difference between the first signal and the second signal; and
acceleration current source circuitry configured to output an acceleration current in response to the trigger signal.

### Claim 20 (depends on 19)

The temperature based acceleration current source circuitry of claim 19, wherein
the first temperature sensitive device generates a first leakage current that varies responsive to temperature changes according to the first rate;
the second temperature sensitive device generates a second leakage current that varies responsive to temperature changes according to the second rate; and
the differential trigger circuitry is configured to generate the trigger signal in response to a difference between a trigger voltage generated by the second leakage current and a bias voltage generated by the first leakage current exceeding a threshold.

### Claim 21 (depends on 20)

The temperature based acceleration current source circuitry of claim 20, wherein
the first temperature sensitive device comprises a first plurality of metal oxide semiconductor (MOS) transistors coupled in parallel between the differential trigger circuitry and a common node, further wherein a body of each MOS transistor in the first plurality is coupled to the differential trigger circuitry and conducts the first leakage current, wherein sources of a first number of the MOS transistors in the first plurality are coupled to the differential trigger circuitry and conduct the first leakage current while sources of a remainder of the first plurality of MOS transistors are open; and
the second temperature sensitive device comprises a second plurality of MOS transistors coupled in parallel between the differential trigger circuitry and the common node, further wherein a body of each MOS transistor in the second plurality is coupled to the differential trigger circuitry and conducts the second leakage current, wherein sources of a second number of the MOS transistors in the second plurality are coupled to the differential trigger circuitry and conduct the second leakage current while sources of a remainder of the second plurality of MOS transistors are open.

### Claim 22 (depends on 21)

The temperature based acceleration current source circuitry of claim 21 wherein a ratio of the first number to the second number is 1 to 6.

### Claim 23 (depends on 22)

The temperature based acceleration current source circuitry of claim 22 wherein the differential trigger circuitry comprises:
a diode device coupled in series with the first temperature sensitive device and biased by the first leakage current to generate the bias voltage; and
a trigger device comprising a trigger MOS transistor having a gate coupled to the diode device and a drain coupled to the second temperature sensitive device and an enable input to the acceleration current source circuitry, wherein the trigger signal corresponds to a voltage present at the drain of the trigger MOS transistor.

### Claim 24 (depends on 23)

The temperature based acceleration current source circuitry of claim 23, wherein the diode device comprises a third plurality of MOS transistors coupled in series, wherein each MOS transistor in the third plurality has a gate coupled to the bias voltage.

### Claim 25 (depends on 24)

The temperature based acceleration current source circuitry of claim 24, wherein the differential trigger circuitry comprises trigger temperature selection circuitry a fourth plurality of transistors, wherein each transistor in the fourth plurality is coupled in parallel with a respective MOS transistor in the third plurality, wherein each transistor in the fourth plurality has a gate coupled to a respective temperature selection input.