PHASE-LOCKED LOOP BASED CONTROLLER FOR ADJUSTING AN ADAPTIVE CONTINUOUS-TIME FILTER

• US 20120133426A1
• Filed: 02/06/2012
• Published: 05/31/2012
• Est. Priority Date: 04/19/2007
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Youssoufian, Edward, Ismail, Aly M., Yates, David, Hatcher, Geoffrey
• Granted Patent: US 9,236,851 B2
• Time in Patent Office: Days
• US Class Current: 327/553
• CPC Class Codes: H03H 11/1291 Current or voltage controlled filters
• CPC Class Codes: H03H 21/0012 Digital adaptive filters
• CPC Class Codes: H03H 2210/021 Amplifier, e.g. transconductance amplifier
• CPC Class Codes: H03H 2210/025 Capacitor
• CPC Class Codes: H03H 2210/028 Resistor
• CPC Class Codes: H03H 2210/036 Stepwise
• CPC Class Codes: H03H 2210/043 by measuring time constant
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank

Abstract

A direct conversion radio-frequency (RF) receiver includes a controller and an adaptive continuous-time filter. The adaptive continuous-time filter receives a multiple-bit control signal generated by the controller to adjust a characteristic of the continuous-time filter. The controller generates the multiple-bit control signal in response to process variation in the semi-conductor material used to implement the controller and the adaptive continuous-time filter. A method for tuning an adaptive continuous-time filter comprises determining a RC time constant, converting the RC time constant to a digital word, comparing a select bit of the digital word to a respective bit of a predetermined reference word to generate a control bit, applying the control bit to an adjustable element to modify the RC time constant, repeating the determining, converting, comparing and applying steps until the control bits generate an output word and providing the output word to the adaptive continuous-time filter.

Claims

1. An adaptive continuous time filter comprising:

a first array of elements; and

a control input configured to receive an output word generated by operative association with a replicator, a digitizer, and a word generator.

2. The filter according to claim 1 wherein said replicator includes a duplicate first array of elements, the replicator generating a first signal having a frequency responsive to a time constant.

3. The filter according to claim 2 wherein said digitizer is configured to receive the first signal from the replicator, the digitizer generating a control signal responsive to the first signal.

4. The filter according to claim 3 wherein said word generator is configured to receive the control signal and a reference signal, the word generator generating the output word responsive to process variation in the semiconductor material used to implement the first array of elements and the duplicate first array of elements.

5. The filter according to claim 4 wherein the replicator further includes an oscillator responsive to an enable signal and generating the first signal based at least in part on the time constant.

6. The filter according to claim 5 wherein the digitizer includes an OR gate and a ripple counter, an input of the OR gate receiving the first signal, an input of the ripple counter receiving an output of the OR gate, the ripple counter producing a multiple-bit output.

7. The filter according to claim 6 wherein the word generator includes a comparator and at least one successive approximation register, the comparator comparing respective bits of the multiple-bit output and the reference signal.

8. The filter according to claim 7 wherein the comparator generates error bits when the respective bits of the multiple-bit output and the reference signal do not match, the successive approximation register receives the error bits and generates bits of the output word.

9. The filter according to claim 8 wherein the first array of elements receives the output word.

10. The filter according to claim 9 wherein the duplicate array of first elements receives the output word to adjust the time constant.

11. A semiconductor die for use in a portable transceiver, the semiconductor die comprising:

an adaptive continuous time filter including a first array of elements and configured to receive an output word; and

a controller comprising a replicator, a digitizer, and a word generator.

12. The filter according to claim 11 wherein said replicator includes a duplicate first array of elements, the replicator generating a first signal having a frequency responsive to a time constant.

13. The filter according to claim 12 wherein said digitizer is configured to receive the first signal from the replicator, the digitizer generating a control signal responsive to the first signal.

14. The filter according to claim 13 wherein said word generator is configured to receive the control signal and a reference signal, the word generator generating the output word responsive to process variation in the semiconductor material used to implement the first array of elements and the duplicate first array of elements.

15. The semiconductor die according to claim 14 wherein the replicator further includes an oscillator responsive to an enable signal and generating the first signal based at least in part on the time constant.

16. The semiconductor die according to claim 15 wherein the digitizer includes an OR gate and a ripple counter, an input of the OR gate receiving the first signal, an input of the ripple counter receiving an output of the OR gate, the ripple counter producing a multiple-bit output.

17. The semiconductor die according to claim 16 wherein the word generator includes a comparator and at least one successive approximation register, the comparator comparing respective bits of the multiple-bit output and the reference signal.

18. The semiconductor die according to claim 17 wherein the comparator generates error bits when the respective bits of the multiple-bit output and the reference signal do not match, the successive approximation register receives the error bits and generates bits of the output word.

19. The semiconductor die according to claim 18 wherein the first array of elements receives the output word.

20. The semiconductor die according to claim 19 wherein the duplicate array of first elements receives the output word to adjust the time constant.