Tunable adaptive filter with variable gain trans-conductance stage

Patent metadata

Field	Value
Publication number	US-9602079-B2
Application number	US-61260809-A
Country	US
Kind code	B2
Filing date	Nov 4, 2009
Priority date	Jun 23, 2009
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

In an exemplary embodiment, the communication device including an analog filter, where a digital signal processor sets the gain of the analog filter and the pole location of the filter simultaneously in order to maintain the filter pole location at a desired value or within a desired range. In further exemplary embodiments, the methodology to simultaneously set the gain and the pole location of the filters.

First claim

The invention claimed is:

1. A device including a baseband processor for setting transconductance g m and pole frequency parameters in an analog filter, comprising:
a gain controller configured to generate, on the basis of a determination of a desired change in gain, a gain control signal to adjust the transconductance g m parameter; and
a decoder configured to generate, on the basis of the determination and the gain control signal, a pole frequency control signal mapped from the gain control signal that simultaneously adjusts the pole frequency to maintain at a specific value a bandwidth of the analog filter across a range of changes to the gain of the analog filter, wherein the gain control signal is configured to selectively switch on a subset of parallel-arranged transconductors, and the pole frequency control signal is configured to selectively switch on a subset of parallel-arranged capacitor elements.

2. The device of claim 1 , wherein the decoder includes means for generating the pole frequency control signal from a precalculated value stored in memory for the associated desired change in gain.

3. The device of claim 1 , wherein the pole frequency control signal is derived in accordance with the following formula:

F

-
3

⁢

⁢
dB

≈

1

(

R
⁢

⁢
1

+

1

g
m

)

·
C

⁢

⁢
1

where F −3dB is filter bandwidth and R 1 and C 1 are the resistance and capacitance, respectively, of an RC circuit in the analog filter.

4. The device of claim 1 , wherein the analog filter is a current mode analog filter.

5. The device of claim 4 , wherein the current mode analog filter is a MOS device.

6. The device of claim 5 , wherein the current mode analog filter is part of an RF transmit and receive circuit.

7. The device of claim 6 , wherein the device includes the RF transmit and receive circuit.

8. A method of setting transconductance g m and pole frequency parameters in an analog filter, comprising:
generating, on the basis of a determination of a desired change in gain, a gain control signal to adjust the transconductance g m parameter; and
generating, on the basis of the determination and the gain control signal, a pole frequency control signal mapped from the gain control signal that simultaneously adjusts the pole frequency to maintain at a specific value a bandwidth of the analog filter across a range of changes to the gain of the analog filter, wherein the gain control signal is configured to selectively switch on a subset of parallel-arranged transconductors, and the pole frequency control signal is configured to selectively switch on a subset of parallel-arranged capacitor elements.

9. The method of claim 8 , wherein the generating the pole frequency control signal involve retrieving a precalculated value stored in memory for the associated desired change in gain.

10. The method of claim 8 , wherein the pole frequency control signal is derived in accordance with the following formula:

F

-
3

⁢

⁢
dB

≈

1

(

R
⁢

⁢
1

+

1

g
m

)

·
C

⁢

⁢
1

where F −3dB is filter bandwidth and R 1 and C 1 are the resistance and capacitance, respectively, of an RC circuit in the current mode analog filter.

11. The method of claim 8 , wherein the analog filter is a current mode analog filter.

12. The method of claim 11 , wherein the current mode analog filter is a MOS device.

13. The method of claim 12 , wherein the current mode analog filter is part of an RF transmit and receive circuit.

14. The method of claim 13 , wherein the RF transmit and receive circuit is part of a wireless communication device.

15. A digital signal processing device for setting transconductance g m and pole frequency parameters in a current mode analog filter, comprising:
means for generating, on the basis of a determination of a desired change in gain, a gain control signal to adjust the transconductance g m parameter; and
means for generating, on the basis of the determination and the gain control signal, a pole frequency control signal mapped from the gain control signal that simultaneously adjusts the pole frequency to maintain at a specific value a bandwidth of the analog filter across a range of changes to the gain of the analog filter, wherein the gain control signal is configured to selectively switch on a subset of parallel-arranged transconductors, and the pole frequency control signal is configured to selectively switch on a subset of parallel-arranged capacitor elements.

16. The device of claim 15 , wherein the means for generating the pole frequency control signal include means for retrieving a precalculated value stored in memory for the associated desired change in gain.

17. The device of claim 15 , wherein the pole frequency control signal is derived in accordance with the following formula:

F

-
3

⁢

Assignees

• Ranjan Mahim
• Qualcomm Inc

Inventors

• Ranjan Mahim

Classifications

• H03H11/1291 Primary

  Current or voltage controlled filters · CPC title