Power optimized ADC for wireless transceivers

• US 7,982,651 B1
• Filed: 03/29/2010
• Issued: 07/19/2011
• Est. Priority Date: 05/02/2008
• Status: Active Grant

• Current Assignee: Maxlinear Asia Singapore Pte Ltd. (Maxlinear Incorporated)
• Original Assignee: PMC-Sierra Incorporated (Microchip Technology Incorporated)
• Inventors: Zortea, Anthony Eugene
• Primary Examiner(s): JEAN PIERRE, PEGUY
• Application Number:
  US12/748,754
• Time in Patent Office: 477 Days
• Field of Search: 341/155, 341/118, 341/120, 341/139
• US Class Current: 341/155
• CPC Class Codes: H03M 1/002 Provisions or arrangements for saving power, e.g. by allowing a sleep mode, using lower supply voltage for downstream stages, using multiple clock domains or by selectively turning on stages when needed
• CPC Class Codes: H03M 1/007 among different resolutions
• CPC Class Codes: H03M 1/183 the feedback signal controlling the gain of an amplifier or attenuator preceding the analogue/digital converter

Abstract

An analog-to-digital converter (ADC) of a radio receiver can consume a relatively large amount of power. It is typically desirable to minimize power consumption, particularly with battery-powered devices, such as in wireless receivers. In certain conditions, the effective number of bits (ENOB) required from an ADC of a receiver can vary. The power consumption of certain ADC topologies, such as pipelined converter topologies, can vary with the number of bits. One embodiment dynamically varies the ENOB of an ADC to more optimally consume power. This can extend battery life.

Claims

1. An apparatus comprising:

an analog-to-digital converter (ADC) configured to convert an analog baseband signal of a radio frequency (RF) receiver from analog to digital, wherein an effective number of bits (ENOB) of the ADC is controllable; and

an ENOB control circuit in communication with the ADC, wherein the ENOB control circuit is responsive to at least one control input, wherein the ENOB control circuit is configured to adaptively control the ENOB of the analog-to-digital converter (ADC) in response to the at least one control input;

wherein the at least one control input comprises one or more of a level of automatic gain control of the RF receiver, a level of the output range of the ADC, or an amount of interference;

wherein the ADC comprises a pipelined ADC, wherein the ENOB control circuit is further configured to adaptively control the effective number of bits of the ADC by control of a settling time of the pipelined ADC, wherein the settling time is associated with at least one switched-capacitor op-amp stage of the pipelined ADC.

2. The apparatus of claim 1, wherein the ENOB control circuit is further configured to adaptively control the ENOB such that the controlled ENOB is lower when the indication of the level of automatic gain control indicates higher gain, and the controlled ENOB is higher when the indication of the level of automatic gain control indicates lower gain.

3. The apparatus of claim 1, wherein the apparatus comprises a transceiver.

4. The apparatus of claim 1, wherein the apparatus comprises a wireless, battery-operated transceiver.

5. The apparatus of claim 1, further comprising an interference scanner configured to determine the amount of interference that is present in an RF signal associated with the analog baseband signal, and wherein the ENOB control circuit is further configured to adaptively control the ENOB based on the level of automatic gain control and the amount of interference.

6. The apparatus of claim 1, further comprising an interference scanner configured to determine an amount of interference that is present in an RF signal corresponding to the analog baseband signal, and wherein the ENOB control circuit is further configured to adaptively control the ENOB based only on the amount of interference.

7. The apparatus of claim 1, further comprising:

a range measurement circuit configured to determine the output range used by the ADC;

wherein the ENOB control circuit is configured to receive an indication of a level of the output range and to adaptively control the ENOB of the ADC based only on the determined output range level.

8. The apparatus of claim 1, wherein the ENOB control circuit is configured to adaptively control the ENOB based on the determined output range and on the level of automatic gain control for an RF signal associated with the analog baseband signal.

9. The apparatus of claim 1, wherein the ENOB control circuit is configured to adaptively control the ENOB based only on the level of automatic gain control of the RF receiver.

10. The apparatus of claim 1, further comprising:

an interference scanner configured to determine an amount of interference that is present in an RF signal associated with the analog baseband signal; and

wherein the ENOB control circuit is configured to adaptively control the ENOB based only on the level of automatic gain control for an RF signal associated with the analog baseband signal and the amount of interference.

11. A method of dynamically adjusting an analog-to-digital converter (ADC) of a radio frequency (RF) receiver, the method comprising:

converting an analog baseband signal of the RF receiver from analog to digital with the ADC; and

adaptively controlling an effective number of bits (ENOB) characteristic of the ADC for conversion of the analog baseband signal based at least partly on one or more of the level of automatic gain control, a level of the output range of the ADC, or an amount of interference;

wherein the ADC comprises a pipelined ADC, wherein adaptively controlling further comprises adjusting a settling time of the pipelined ADC, wherein the settling time is associated with at least one switched-capacitor op-amp stage of the pipelined ADC.

12. The method of claim 11, further comprising adaptively controlling the ENOB such that the controlled ENOB is lower when the indication of the level of automatic gain control indicates higher gain, and the controlled ENOB is higher when the indication of the level of automatic gain control indicates lower gain.

13. The method of claim 11, wherein the RF receiver is embodied in a transceiver.

14. The method of claim 11, wherein the RF receiver is embodied in a wireless, battery-operated transceiver.

15. The method of claim 11, further comprising determining the amount of interference that is present in an RF signal associated with the analog baseband signal, and adaptively controlling the ENOB based on the level of automatic gain control and the amount of interference.

16. The method of claim 11, further comprising determining the amount of interference that is present in an RF signal corresponding to the analog baseband signal, and adaptively controlling the ENOB based only on the amount of interference.

17. The method of claim 11, further comprising:

determining the output range used by the ADC to convert the analog baseband signal from analog to digital; and

adaptively controlling an effective number of bits (ENOB) for conversion based only on the determined output range.

18. The method of claim 11, wherein adaptively controlling further comprises adjusting a settling time of the ADC.

19. The method of claim 11, further comprising adaptively controlling the ENOB based on the determined output range and on the level of automatic gain control for an RF signal associated with the analog baseband signal.

20. The method of claim 11, further comprising adaptively controlling the ENOB based only on the level of automatic gain control for an RF signal associated with the analog baseband signal.

21. The method of claim 11, further comprising:

determining an amount of interference that is present in an RF signal corresponding to the analog baseband signal; and

adaptively controlling the ENOB based on the determined output range, on the level of automatic gain control for an RF signal associated with the analog baseband signal, and the amount of interference.

22. An apparatus comprising:

an analog-to-digital converter (ADC) configured to convert an analog baseband signal of a radio frequency (RF) receiver from analog to digital, wherein an effective number of bits (ENOB) of the ADC is controllable; and

an ENOB control circuit in communication with the ADC, wherein the ENOB control circuit is responsive to at least one control input, wherein the ENOB control circuit is configured to adaptively control the ENOB of the analog-to-digital converter (ADC) in response to the at least one control input;

wherein the at least one control input comprises one or more of a level of automatic gain control of the RF receiver, a level of the output range of the ADC, or an amount of interference;

wherein the ADC comprises a pipelined ADC, wherein the ENOB control circuit is further configured to adaptively control the effective number of bits of the ADC by at least one of control of a settling time of the ADC or selective activation of one or more stages of the pipelined ADC, wherein the settling time is associated with at least one switched-capacitor op-amp stage of the pipelined ADC.

23. A method of dynamically adjusting an analog-to-digital converter (ADC) of a radio frequency (RF) receiver, the method comprising:

converting an analog baseband signal of the RF receiver from analog to digital with the ADC; and

adaptively controlling an effective number of bits (ENOB) characteristic of the ADC for conversion of the analog baseband signal based at least partly on one or more of the level of automatic gain control, a level of the output range of the ADC, or an amount of interference;

wherein the ADC comprises a pipelined ADC, wherein adaptively controlling further comprises adjusting a settling time of the pipelined ADC or selective activation of one or more stages of the pipelined ADC, wherein the settling time is associated with at least one switched-capacitor op-amp stage of the pipelined ADC.