INTEGRATOR FOR CLASS D AUDIO AMPLIFIER

• US 20150263676A1
• Filed: 03/14/2014
• Published: 09/17/2015
• Est. Priority Date: 03/14/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sienko, Matthew David, Srivastava, Ankit, Mishra, Manu, Lu, Jingxue
• Granted Patent: US 9,461,595 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03F 1/0233 by using a signal derived from the output signal, e.g. bootstrapping the voltage supply
• CPC Class Codes: H03F 1/30 Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in differential amplifiers H03F3/45479
• CPC Class Codes: H03F 2200/03 the amplifier being designed for audio applications
• CPC Class Codes: H03F 3/183 with semiconductor devices only
• CPC Class Codes: H03F 3/185 with field-effect devices H03F3/187 takes precedence
• CPC Class Codes: H03F 3/2173 of the bridge type
• CPC Class Codes: H03F 3/45076 characterised by the way of implementation of the active amplifying circuit in the differential amplifier

Abstract

An apparatus includes voltage-to-current conversion circuitry comprising a first voltage-to-current converter and a second voltage-to-current converter. The apparatus also includes a capacitor coupled to the first voltage-to-current converter and to the second voltage-to-current converter.

Claims

1. An apparatus comprising:

voltage-to-current conversion circuitry comprising a first voltage-to-current converter and a second voltage-to-current converter; and

a capacitor coupled to the first voltage-to-current converter and to the second voltage-to-current converter.

2. The apparatus of claim 1, wherein the first voltage-to-current converter and the second voltage-to-current converter are configured to selectively change and discharge the capacitor.

3. The apparatus of claim 1, wherein the second voltage-to-current converter is configured to convert voltage signals from a pair of comparators into current signals.

4. The apparatus of claim 1, wherein the first voltage-to-current converter comprises a first differential operational amplifier, and wherein the second voltage-to-current converter comprises a second differential operational amplifier.

5. The apparatus of claim 1, further comprising:

a first comparator configured to compare a voltage level at a positive terminal of the capacitor to a voltage level of a signal; and

a second comparator configured to compare a voltage level at a negative terminal of the capacitor to the voltage level of the signal.

6. The apparatus of claim 5, wherein the first comparator generates a first pulse width modulation signal based on the comparison, and wherein the second comparator generates a second pulse width modulation signal based on the comparison.

7. The apparatus of claim 6, further comprising:

a first power switch coupled to receive the first pulse width modulation signal; and

a second power switch coupled to receive the second pulse width modulation signal.

8. The apparatus of claim 1, further comprising a common mode circuit coupled to a first terminal of the capacitor and to a second terminal of the capacitor.

9. The apparatus of claim 1, wherein the voltage-to-current conversion circuitry and the capacitor are included in an integrator.

10. The apparatus of claim 9, further comprising feed-forward biasing circuitry coupled to generate a feed-forward current, the feed-forward current provided to an output of the integrator to reduce a voltage swing at the output of the integrator.

11. The apparatus of claim 10, wherein the output of the integrator is a differential output, and wherein the feed-forward current includes a first feed-forward current provided to a first output of the differential output and a second feed-forward current provided to a second output of the differential output.

12. A method comprising:

converting differential input voltage signals into differential input current signals;

converting voltage signals from comparators into feedback current signals; and

selectively charging and discharging a capacitor based on the differential input current signals and the feedback current signals.

13. The method of claim 12, further comprising comparing a voltage level of a signal to a voltage at a first terminal of the capacitor to generate a first pulse width modulated signal.

14. The method of claim 13, further comprising comparing the voltage level of the signal to a voltage at a second terminal of the capacitor to generate a second pulse width modulated signal.

15. An apparatus comprising:

means for converting voltage signals into current signals; and

means for storing energy coupled to the means for converting voltage signals into current signals.

16. The apparatus of claim 15, wherein the means for storing energy selectively charges and discharges based on the current signals.

17. The apparatus of claim 15, further comprising means for comparing a voltage level of a signal to a voltage at a positive terminal of the means for storing energy to generate a first pulse width modulated signal.

18. The apparatus of claim 17, further comprising means for comparing the voltage level of the signal to a voltage at a negative terminal of the means for storing energy to generate a second pulse width modulated signal.

19. The apparatus of claim 18, further comprising:

first switching means coupled to receive the first pulse width modulated signal; and

second switching means coupled to receive the second pulse width modulated signal.

20. The apparatus of claim 15, further comprising means for generating a feed-forward current, the feed-forward current provided to an output of the means for converting to reduce a voltage swing at the output of the means for converting.