Notch filter with successive windowed integrations, related band-pass filtering device, frequency detection system and processing method

Patent metadata

Field	Value
Publication number	US-11575399-B2
Application number	US-202117450574-A
Country	US
Kind code	B2
Filing date	Oct 12, 2021
Priority date	Oct 16, 2020
Publication date	Feb 7, 2023
Grant date	Feb 7, 2023

Abstract

This electronic notch filter is able to receive an input signal and deliver a filtered signal having an amplitude, at a cut-off frequency, that is attenuated with respect to that of the input signal.It comprises a module for integrating the input signal during several successive time windows, each time window starting at a respective initial time instant and having a duration substantially equal to the inverse of the cut-off frequency, the initial temporal time instants of at least two distinct windows being separated by a temporal shift of a value greater than or equal to a predefined reference duration, each integration of the input signal during a respective temporal window resulting in a respective intermediate signal; and a module for summing the intermediate signals coming from the integration module; the filtered signal depending on the sum of said intermediate signals.

First claim

The invention claimed is:

1. An electronic band-pass filtering device able to receive an input signal and deliver an output signal having an amplitude, outside a frequency band centered around a target frequency, that is attenuated with respect to that of the input signal, the device comprising:
a first notch filter, able to receive the input signal and deliver a first filtered signal having an amplitude, at a first cutoff frequency, that is attenuated with respect to that of the input signal, the first cutoff frequency being substantially equal to the target frequency,
a second notch filter, able to receive the input signal and deliver a second filtered signal having an amplitude, at a second cutoff frequency, that is attenuated with respect to that of the input signal, the second cutoff frequency being distinct from the first cutoff frequency,
a generation module connected to the output of the first and second notch filters, configured to generate the output signal from a combination of the first and second filtered signals,
wherein at least one of the first and second notch filters comprises:
an integration module configured to integrate the input signal during several successive time windows, each time window starting at a respective initial time instant and having a duration substantially equal to the inverse of the cutoff frequency, the initial time instants of at least two distinct windows being separated by a time shift of value greater than or equal to a predefined reference duration, each integration of the input signal during a respective time window resulting in a respective intermediate signal,
a summing module connected to an output of the integration module and configured to add up the intermediate signals coming from the integration module, the filtered signal depending on the sum of said intermediate signals.

2. The device according to claim 1 , wherein each of the first and second notch filters comprises the integration module and the summing module.

3. The device according to claim 1 , wherein the integration module is configured to integrate the input signal during No first successive time windows, then during Nb second successive time windows, with No and Nb each being an integer greater than or equal to 2, the initial time instants of the No first windows being all included in a first time period of duration substantially equal to the reference duration, and the initial time instants of the Nb second windows being all subsequent to the first time period.

4. The device according to claim 3 , wherein the initial time instants of the No first windows are regularly distributed during the first time period.

5. The device according to claim 3 , wherein the initial time instants of the Nb second windows are regularly distributed during a second time period, subsequent to the first time period.

6. The device according to claim 5 , wherein the second time period is substantially equal in duration to the reference duration.

7. The device according to claim 1 , wherein a transfer function module for integrating the input signal during a respective time window satisfies the following equation:



G
⁡

(
f
)



=

2
⁢

(

1
-

cos
⁡

(

2
⁢
π
⁢

⁢

fT
int

)

)

f

F
int

where G represents the gain and f the frequency,
T int represents the duration of the respective time window; and
F int satisfies the following equation:

F
int

=

g
m

2
⁢
π
⁢

⁢

C
int

with g m representing a transconductance of the integration, and,
C int representing a capacitance of the integration.

8. The device according to claim 1 , wherein the integration module comprises at least one integration unit, each integration unit being connected to an input of the summing module and configured to perform an integration of the input signal during at least one time window.

9. The device according to claim 8 , wherein the integration module comprises multiple integration units arranged in parallel with each other, each of which is configured to perform an integration of the input signal during a respective time window.

10. The device according to claim 1 , wherein the summing module is a digital module, and the integration module comprises at least one analog-to-digital converter, the input signal being an analog signal.

11. The device according to claim 8 , wherein each integration unit comprises an analog conversion stage, an averaging stage and an analog-to-digital converter.

12. The device according to claim 11 , wherein an analog-to-digital converter with successive approximation register forms the averaging stage and the analog-to-digital converter.

13. The device according to claim 1 , wherein the integration module and the summing module are each an analog module, the input signal being an analog signal.

14. The device according to claim 1 , wherein the second cutoff frequency is substantially equal to two-thirds of the target frequency or substantially equal to twice the target frequency.

15. The device according to claim 1 , wherein the predefined reference duration is equal to the inverse of the target frequency.

16. The device according to claim 1 , wherein the combination of the first and second filtered signals is a linear combination.

17. The device according to claim 16 , wherein the linear combination of the first and second filtered signals satisfies the following equation:
Ys=E 2− K·E 1

where Ys represents the output signal,
E 1 represents the first filtered signal,
E 2 represents the second filtered signal,
K

Assignees

• Commissariat Energie Atomique

Inventors

• Masson Gilles

Classifications

• H03H17/0291

  Digital and sampled data filters · CPC title

• H03H11/0466

  Filters combining transconductance amplifiers with other active elements, e.g. operational amplifiers, transistors, voltage conveyors · CPC title

• H04B2001/1054

  by changing bandwidth · CPC title

• H04B2001/1063

  using a notch filter · CPC title

• H04B1/1036 Primary

  with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters (H04B1/123 takes precedence; filter circuits H03H) · CPC title