Voltage reference circuit, voltage detector and voltage detector system

Patent metadata

Field	Value
Publication number	US-10914768-B2
Application number	US-201716096771-A
Country	US
Kind code	B2
Filing date	Apr 27, 2017
Priority date	Apr 27, 2016
Publication date	Feb 9, 2021
Grant date	Feb 9, 2021

Abstract

A voltage detector (200) for monitoring an input signal and outputting a detection signal at an output when a voltage of the input signal meets a first threshold having: an input configured for receiving the input signal; a voltage reference circuit for receiving an input voltage and producing a reference voltage having a maximum value independent of the input voltage; and a trigger configured to compare the input signal and the reference voltage and to output a detection signal to the output when the voltage of the input signal reaches the first threshold. The voltage reference circuit comprises a reset input connected to either the input or the output and is configured to reduce the reference voltage when a predetermined reset signal is received. The voltage reference circuit may include: an input for receiving the input voltage; a first current controlling element (210), such as a diode, which allows current to flow as an increasing, non-linear function of voltage at least within a first range of voltages; a second current controlling element (240), such as a transistor, which allows current to flow as an increasing, non-linear function of voltage at least with a second range of voltages; and an output at which the output reference voltage is produced. The first current controlling element and the second current controlling element are connected in series between the input and a common reference, with the second current controlling element between the first current controlling element and a common reference, the output comprises a node between the two current controlling elements, the first and second range of voltages overlap and the second current controlling element is configured to vary the function by which it allows current to flow in dependence on the input voltage.

First claim

The invention claimed is:

1. A voltage reference circuit for receiving an input and producing an output reference voltage having a maximum value independent of a voltage of the input, the voltage reference circuit comprising:
an input for receiving the input voltage;
a first current controlling element which allows current to flow as an increasing, non-linear function of voltage at least within a first range of voltages;
a second current controlling element which allows current to flow as an increasing, non-linear function of voltage at least with a second range of voltages; and
an output at which the output reference voltage is produced,
wherein the first current controlling element and the second current controlling element are connected in series between the input and a common reference, with the second current controlling element between the first current controlling element and the common reference, the output comprises a node between the two current controlling elements, the first and second range of voltages overlap and the second current controlling element is configured to vary the function by which it allows current to flow in dependence on the input voltage;
a reset input for receiving a reset signal; and
a third current controlling element connected in series between the first current controlling element and the output,
wherein the third current controlling element is configured to allow current to flow in dependence on a voltage received at the reset input.

2. A voltage reference circuit according to claim 1 wherein the second current controlling element has a control terminal connected to the input.

3. A voltage reference circuit as claimed in claim 1 wherein the reset input is connected to the input so that the third current controlling element is configured to allow current to flow in dependence on the input voltage.

4. A voltage reference circuit according to claim 1 wherein the third current controlling element has a control terminal connected to the reset input.

5. A voltage reference circuit according to claim 1 arranged to reduce the output reference voltage when a predetermined reset signal is received.

6. A voltage reference circuit according to claim 1 comprising a capacitance connected to the input via the first current controlling element.

7. A voltage reference circuit according to claim 1 comprising a bias-shifting element associated with the second current controlling element.

8. A voltage reference circuit according to claim 1 connected to a trigger configured to compare the input voltage with the output reference voltage and to output a detection signal when the voltage of the input meets a first threshold.

9. A voltage detector for monitoring an input signal and outputting a detection signal at an output when a voltage of the input signal meets a first threshold, the voltage detector comprising:
an input configured for receiving the input signal;
a voltage reference circuit for receiving an input voltage and producing a reference voltage having a maximum value independent of the input voltage; and
a trigger configured to compare the input signal and the reference voltage and to output a detection signal to the output when the voltage of the input signal reaches the first threshold,
wherein the voltage reference circuit comprises a reset input connected to either the input or the output and is configured to reduce the reference voltage when a predetermined reset signal is received.

10. A voltage detector according to claim 9 wherein the voltage reference circuit is according to claim 1 .

11. A voltage detector according to claim 9 wherein the trigger is an inverter, the voltage reference circuit comprises a capacitance connected to the input via a first current controlling element, and the voltage reference circuit acts as a switch for selectively connecting an input of the inverter to the capacitance or to a common reference, wherein:
the switch is operative to connect the input of the inverter to the capacitance during a period in which a voltage of the input signal rises from zero to the first threshold, such that no detection signal is output;
the switch is operative to connect the input of the inverter to the common reference when the voltage of the input signal meets the first threshold, such that a detection signal is output while the voltage of the input signal is equal to or greater than the first threshold; and
the switch is operative to connect the input of the inverter to the capacitance when the voltage of the input signal drops below a second threshold, such that no detection signal is output.

12. A voltage detector according to claim 9 configured to stop outputting a detection signal when a voltage of the input falls below a second threshold which is lower than the first threshold.

13. A voltage detector system for monitoring an input signal and outputting a detection signal when the voltage of the input signal meets a threshold, the voltage detector system comprising:
a first voltage detector having a first reference generator and an input for receiving the input signal and an output for outputting a detection signal, wherein the first voltage detector is configured to output the detection signal when the voltage of the input signal meets a first rising input voltage threshold;
a second voltage detector having a second reference generator and an input for receiving the input signal and an output for outputting a detection signal, wherein the second voltage detector is configured to output the detection signal when the voltage of the input signal meets a second rising input voltage threshold which is higher than the first rising input voltage threshold,
wherein the output of the second voltage detector controls a connection between the input signal and the input of the first voltage detector such that when the voltage of the input signal meets the second rising input voltage threshold the connection between the input signal and input of the first voltage detector is restricted or disconnected.

14. A voltage detector system according to claim 13 further comprising:
a third voltage detector having a third reference generator and an input for receiving the input signal and an output for outputting a detection signal, wherein the third voltage detector is configured to output the detection signal when the voltage of the input signal meets a third rising input voltage threshold which is higher than both the first rising input voltage threshold and the second rising input voltage threshold,
wherein the output of the third voltage detector controls a connection between the input signal and the input of the second voltage detector such that when the voltage of the input signal meets the third rising input voltage threshold the connection between the input signal and the input of the second voltage detector is restricted or disconnected.

15. A voltage detector system according to claim 14 , wherein the third voltage detector is configured to cease outputting a detection signal when the voltage of the input signal meets a third falling input voltage threshold, wherein the third falling input voltage threshold is lower than the third rising input voltage threshold.

16. A voltage detector system according to claim 14 wherein the first, second and/or third voltage detector comprises a voltage detector according to claim 9 .

17. A voltage detector system according to claim 13 , wherein the first voltage detector is configured to cease outputting a detection signal when the voltage of the input signal meets a first fal

Assignees

• Univ Bristol

Inventors

• Stark Bernard
• Yang Guang
• Zhang Chunhong
• Proynov Plamen
• Adami Salah

Classifications

• G01R19/16538 Primary

  in AC or DC supplies (G01R19/16519 and G01R19/16528 take precedence) · CPC title

• G01R19/16519

  using FET's · CPC title

• G05F3/24

  wherein the transistors are of the field-effect type only (G05F3/205, G05F3/26, G05F3/30 take precedence) · CPC title

• H03K17/223

  in field-effect transistor switches · CPC title

• G05F3/10 Primary

  using uncontrolled devices with non-linear characteristics · CPC title