555-timer based time-to-voltage converter

• US 10,324,420 B1
• Filed: 03/19/2018
• Issued: 06/18/2019
• Est. Priority Date: 03/19/2018
• Status: Active Grant

• Current Assignee: King Fahd University Of Petroleum And Minerals
• Original Assignee: King Fahd University Of Petroleum And Minerals
• Inventors: Abuelma'atti, Muhammad Taher
• Primary Examiner(s): Jeanglaude, Jean B
• Application Number:
  US15/925,227
• Time in Patent Office: 456 Days
• Field of Search: 341155, 341166
• CPC Class Codes: G04F 10/005 Time-to-digital converters [TDC] analog-to-digital converters with intermediate conversion to time or phase H03M1/50, H03M1/60
• CPC Class Codes: G04F 10/10 by measuring electric or magnetic quantities changing in proportion to time
• CPC Class Codes: H03K 4/08 having sawtooth shape
• CPC Class Codes: H03M 1/12 Analogue/digital converters H03M1/001 – H03M1/10 take precedence

Abstract

A time-to-voltage converter (TVC) that includes a 555 timer integrated circuit (IC), and a charging circuit including a constant current source and a capacitor connected in series. The capacitor can be connected to a discharge pin of the 555 timer IC. The TVC can further include a trigger circuit and a reset circuit to receive a start signal and a stop signal, respectively, from an input line, and accordingly generate a trigger signal or a reset signal to trigger or reset the 555 timer IC. A switch can be configured to, under control of an output signal of the 555 timer IC, connect the input line with the reset circuit. A voltage across the capacitor when the 555 timer IC is reset indicates a time interval corresponding to the start and stop signals.

Claims

1. A time-to-voltage converter (TVC), comprising:

a 555 timer integrated circuit (IC);

a charging circuit including a constant current source and a capacitor connected in series, the capacitor being connected to a discharge pin of the 555 timer IC;

a trigger circuit configured to,

receive a start signal from an input line, and

generate a trigger signal corresponding to the start signal to trigger the 555 timer IC;

a reset circuit configured to,

receive a stop signal from the input line via a switch, and

generate a reset signal corresponding to the stop signal to reset the 555 timer IC; and

the switch configured to, under control of an output signal of the 555 timer IC, connect the input line with the reset circuit when the 555 timer IC is enabled.

2. The TVC of claim 1, wherein a voltage across the capacitor when the 555 timer IC is reset indicates a time interval corresponding to the start and stop signals.

3. The TVC of claim 1, wherein the trigger signal corresponds to a voltage transition in the start signal.

4. The TVC of claim 1, wherein the reset signal corresponds to a voltage transition in the stop signal.

5. The TVC of claim 1, wherein the trigger circuit includes a differentiator circuit.

6. The TVC of claim 1, wherein the trigger circuit includes an RC differentiator circuit.

7. The TVC of claim 1, wherein the reset circuit includes a differentiator circuit.

8. The TVC of claim 1, wherein the reset circuit includes an RC differentiator circuit.

9. The TVC of claim 1, wherein the switch is implemented with an AND gate with output of the 555 timer IC and the input line as input.

10. The TVC of claim 1, further comprising:

an analog-to-digital converter (ADC) configured to convert a voltage across the capacitor to digital bits; and

latches configured to store the digital bits when the 555 timer IC is reset.

11. The TVC of claim 1, wherein the capacitor being connected to a threshold pin of the 555 timer IC.

16. A range finding device, comprising:

a light transmitter configured to transmit an optical pulse to a target;

a receiver configured to receive the optical pulse and a reflected pulse corresponding to the transmitted optical pulse, and generate a start signal and a stop signal corresponding to the optical pulse and the reflected pulse, respectively; and

the TVC according to claim 10, configured to receive the start and stop signals from the receiver at the input line, and generate digital bits indicating a flight time of the optical pulse between transmission of the optical pulse and reception of the reflective pulse.

17. The range finding device of claim 16, further comprising:

a display device configured to receive the digital bits indicating the flight time of the optical pulse between transmission of the optical pulse and reception of the reflective pulse, and display a distance corresponding to the flight time of the optical pulse.

12. A time-to-voltage converter (TVC), comprising:

a 555 timer integrated circuit (IC);

a charging circuit including a constant current source and a capacitor connected in series, the capacitor being connected to a discharge pin and a threshold pin of the 555 timer IC;

a trigger circuit including an RC differentiator circuit and configured to,

receive a start signal from an input line, and

generate a trigger signal corresponding to a voltage transition in the start signal to trigger the 555 timer IC;

a reset circuit including an RC differentiator circuit and configured to,

receive a stop signal from the input line via an AND gate, and

generate a reset signal corresponding to the stop signal to reset the 555 timer IC; and

the AND gate with output of the 555 timer IC and the input line as input,

wherein a voltage across the capacitor indicates a time interval corresponding to the start and stop signals.

13. The TVC of claim 12, wherein the trigger signal corresponds to a voltage transition in the start signal.

14. The TVC of claim 12, wherein the reset signal corresponds to a voltage transition in the stop signal.

15. The TVC of claim 12, further comprising:

an analog-to-digital converter (ADC) configured to convert the voltage across the capacitor to digital bits; and

latches configured to store the digital bits when the 555 timer IC is reset.