Method and device for measuring the frequency of a signal

Patent metadata

Field	Value
Publication number	US-10823771-B2
Application number	US-201916280190-A
Country	US
Kind code	B2
Filing date	Feb 20, 2019
Priority date	Nov 19, 2015
Publication date	Nov 3, 2020
Grant date	Nov 3, 2020

Abstract

A method includes a) counting whole periods of a signal during a first period of a reference signal, b) repeating step a) for each period of the reference signal until a first duration is equal to a first quantity of periods of the reference signal, and c) determining a first average of the whole periods. The method also includes repeating at least one of steps a) to c) and at each repetition shifting a start of the counting of step a) by at least one period of the reference signal, and in steps b) and c) accounting for whole periods of the signal already counted during the at least one preceding group of steps a) and b). The method includes determining a second average of the first averages, and determining the frequency of the signal from the second average and the frequency of the reference signal.

First claim

What is claimed is:

1. A method for determining a frequency of a signal using a frequency measurement circuit, the method comprising, using the frequency measurement circuit:
a) counting a number of whole periods of the signal during a first period of a periodic reference signal;
b) repeating step a) for each period of the periodic reference signal until a first duration is equal to a first quantity of periods of the periodic reference signal;
c) determining a first average of the numbers of whole periods;
d) repeating at least one of steps a), b) and c) and at each repetition shifting a start of the counting of step a) by at least one period of the periodic reference signal;
e) determining a second average of the first averages; and
f) determining the frequency of the signal from the second average and the frequency of the periodic reference signal by multiplying the second average times the frequency of the periodic reference signal.

2. The method of claim 1 , wherein repeating at least one of steps a), b) and c) comprises repeating steps a), b) and c) in parallel.

3. The method of claim 1 , wherein steps a) to e) are implemented by applying the following formula:

M
⁢

⁢
2

=

1
R

*

(

∑

k
=
1

R

⁢

1
S

⁢

∑

i
=
k

k
+
S
-
1

⁢

C
i

)

wherein M 2 designates the second average, S corresponds to the first quantity of periods, R corresponds to a number of repetitions of steps during step d), and C i corresponds to the number of whole periods of the signal counted during a current period of the periodic reference signal.

4. The method of claim 1 , wherein the repetitions of steps a), b) and c) is equal to a second quantity of periods of the periodic reference signal reduced by the first quantity of periods.

5. The method of claim 4 , wherein the first quantity and the second quantity of periods are powers of two.

6. The method of claim 5 , wherein the first quantity of periods is equal to half the second quantity of periods.

7. The method of claim 6 , wherein steps a) to e) are implemented by applying the following formula:

M
⁢

⁢
2

=

1

P
-
S

*

1
S

*

(

∑

i
=
1

S

⁢

i
*

C
i

+

∑

i
=

S
+
1

P
-
1

⁢

(

P
-
i

)

*

C
i

)

wherein M 2 designates the second average, S corresponds to the first quantity of periods, P corresponds to the second quantity of periods and C i corresponds to the number of whole periods of the signal counted during a current period of the periodic reference signal.

8. The method of claim 5 , wherein the first quantity of periods is less than half the second quantity of periods.

9. The method of claim 8 , wherein steps a) to e) are implemented by applying the following formula:

M
⁢

⁢
2

=

1

P
-
S

*

1
S

*

(

∑

i
=
1

S

⁢

i
*

C
i

+

∑

i
=

S
+
1

Assignees

• St Microelectronics Sa

Inventors

• Houdebine Marc
• Dedieu Sebastien

Classifications

• G01R23/10 Primary

  by converting frequency into a train of pulses, which are then counted {, i.e. converting the signal into a square wave} · CPC title

• G01R23/02

  Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage · CPC title

• H03D13/001

  in which a pulse counter is used followed by a conversion into an analog signal · CPC title