Current-mode filtering using current steering

Patent metadata

Field	Value
Publication number	US-10630328-B2
Application number	US-201816058944-A
Country	US
Kind code	B2
Filing date	Aug 8, 2018
Priority date	Aug 8, 2018
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

An apparatus is disclosed for current-mode filtering using current steering. In an example aspect, the apparatus includes a filter. The filter includes a current-steering node, a first output node, a second output node, a wideband path, and a narrowband path. The wideband path is coupled between the current-steering node and the first output node. The wideband path includes a wideband low-pass filter configured to pass frequencies within a wide passband. The narrowband path is coupled between the current-steering node and the second output node. The narrowband path includes a narrowband low-pass filter configured to pass a portion of the frequencies that are within a narrow passband.

First claim

What is claimed is:

1. An apparatus comprising:
a filter including:
a current-steering node;
a first output node and a second output node;
a wideband path coupled between the current-steering node and the first output node, the wideband path including a wideband low-pass filter configured to pass frequencies within a wide passband, the wideband low-pass filter including a wideband transimpedance amplifier coupled in series along the wideband path between the current-steering node and the first output node; and
a narrowband path coupled between the current-steering node and the second output node, the narrowband path including a narrowband low-pass filter configured to pass a portion of the frequencies that are within a narrow passband, the narrowband low-pass filter including a narrowband transimpedance amplifier coupled in series along the narrowband path between the current-steering node and the second output node.

2. The apparatus of claim 1 , further comprising:
an input node; and
a low-pass filter coupled between the input node and the current-steering node, the low-pass filter comprising one or more passive components.

3. The apparatus of claim 1 , wherein the wideband path includes a low-pass filter coupled between the current-steering node and the wideband low-pass filter.

4. The apparatus of claim 1 , further comprising:
a low-noise amplifier;
a mixer coupled between the low-noise amplifier and the current-steering node;
a first analog-to-digital converter coupled to the first output node; and
a second analog-to-digital converter coupled to the second output node.

5. The apparatus of claim 1 , wherein:
the narrowband low-pass filter is configured to have an impedance; and
the wideband low-pass filter is configured to have another impedance that is larger within the narrow passband and smaller within a portion of the wide passband that is outside of the narrow passband relative to the impedance of the narrowband low-pass filter.

6. The apparatus of claim 5 , wherein:
the current-steering node is configured to accept an input current comprising a low-frequency current having frequencies within the narrow passband; and
the narrowband path is configured to steer the low-frequency current to the narrowband low-pass filter based on the impedance of the narrowband low-pass filter being smaller than the other impedance of the wideband low-pass filter within the narrow passband.

7. The apparatus of claim 6 , wherein the input current comprises differential currents associated with an in-phase current or a quadrature current.

8. The apparatus of claim 6 , wherein the low-frequency current is associated with at least one of the following:
a second-generation (2G) wireless signal;
a third-generation (3G) wireless signal; or
a fourth-generation (4G) wireless signal.

9. The apparatus of claim 6 , wherein:
the input current comprises a high-frequency current having other frequencies that are within the wide passband and outside the narrow passband; and
the wideband path is configured to steer the high-frequency current from the current-steering node to the wideband low-pass filter based on the other impedance of the wideband low-pass filter being smaller than the impedance of the narrowband low-pass filter within the wide passband and outside the narrow passband.

10. The apparatus of claim 9 , further comprising an analog-to-digital converter coupled to the second output node, wherein:
the low-frequency current is associated with a jammer;
the high-frequency current is associated with at least one high-frequency narrowband signal having a center frequency that is offset relative to another center frequency of the jammer; and
the analog-to-digital converter is configured to be in an inactive state to avoid processing the jammer.

11. The apparatus of claim 9 , wherein:
the high-frequency current is associated with at least one high-frequency narrowband signal;
the low-frequency current is associated with a low-frequency narrowband signal;
the at least one high-frequency narrowband signal and the low-frequency narrowband signal comprise at least two non-contiguous signals; and
the wideband low-pass filter and the narrowband low-pass filter are together configured to cause amplitudes of the at least two non-contiguous signals to be relatively similar.

12. The apparatus of claim 9 , wherein:
the high-frequency current is associated with at least one high-frequency narrowband signal;
the low-frequency current is associated with a low-frequency narrowband signal;
the at least one high-frequency signal and the low-frequency narrowband signal comprise at least two contiguous signals; and
the wideband low-pass filter and the narrowband low-pass filter are together configured to cause amplitudes of the at least two contiguous signals to be relatively similar.

13. The apparatus of claim 1 , wherein the narrowband path includes a switch coupled between the current-steering node and the narrowband low-pass filter, the switch configured to connect or disconnect the narrowband path to or from the current-steering node.

14. The apparatus of claim 13 , wherein:
the current-steering node is configured to accept an input current associated with a low-frequency wideband signal having the frequencies within the wide passband of the wideband low-pass filter; and
the wideband path is configured to steer the input current from the current-steering node to the wideband low-pass filter based on the switch disconnecting the narrowband path from the current-steering node.

15. The apparatus of claim 14 , wherein the low-frequency wideband signal is associated with a fifth-generation (5G) wireless signal.

16. The apparatus of claim 13 , wherein:
the second output node is coupled to the first output node; and
the narrowband path includes another switch coupled between the narrowband low-pass filter and the first output node.

17. The apparatus of claim 16 , wherein:
the wideband path is configured to provide a low-frequency wideband signal at the first output node based on both the switch and the other switch being in an open state; and
the narrowband path is configured to provide a low-frequency narrowband signal at the first output node based on both the switch and the other switch being in a closed state.

18. An apparatus comprising:
a filter including:
a current-steering node configured to accept an input current comprising at least a high-frequency narrowband signal a low-frequency narrowband signal, and a low-frequency wideband signal;
a first output node and a second output node;
a wideband path coupled between the current-steering node and the first output node, the wideband path including wideband filter means for passing the high-frequency narrowband signal to the first output node;
a narrowband path coupled between the current-steering node and the second output node, the narrowband path including narrowband filter means for passing the low-frequency narrowband signal to the second output node; and
impedance means for steering the high-frequency narrowband signal and the low-frequency narrowband signal to the wideband path and the narrowband path, respectively, the impedance means comprising switch means for disconnecting the narrowband path from the current-steering node, the impedance means configured to steer the low-frequency wideband signal to the wideband path, the wideband filter means configured to pass the low-frequency wideband signal to the first output node.

19. The apparatus of c

Assignees

• Qualcomm Inc

Inventors

• Gathman Timothy Donald
• Patel Chirag Dipak
• Leung Lai Kan

Classifications

• H04B1/0053

  with common antenna for more than one band · CPC title

• H03F3/193 Primary

  with field-effect devices (H03F3/195 takes precedence) · CPC title

• H03H11/0427

  Filters using a single transconductance amplifier; Filters derived from a single transconductor filter, e.g. by element substitution, cascading, parallel connection (H03H11/0433 - H03H11/0472 take precedence) · CPC title

• H03F2200/91

  the amplifier has a current mode topology · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title