SYSTEM AND METHOD OF ENABLING A SIGNAL PROCESSING DEVICE IN A RELATIVELY FAST MANNER TO PROCESS A LOW DUTY CYCLE SIGNAL

• US 20090224832A1
• Filed: 03/10/2008
• Published: 09/10/2009
• Est. Priority Date: 03/10/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Fagg, Russell John
• Granted Patent: US 7,812,667 B2
• Time in Patent Office: Days
• US Class Current: 330/277
• CPC Class Codes: H02J 7/345 using capacitors as storage or buffering devices
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2203/30099 the pull transistor being gated by a switching element
• CPC Class Codes: H03F 2203/30132 the push transistor being gated by a switching element
• CPC Class Codes: H03F 2203/7206 the gated amplifier being switched on or off by a switch in the bias circuit of the amplifier controlling a bias voltage in the amplifier
• CPC Class Codes: H03F 2203/7215 the gated amplifier being switched on or off by a switch at the input of the amplifier
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal

Abstract

A system and method of improving the power efficiency of a receiver for low duty cycle applications. In one aspect, the receiver includes a low noise amplifier (LNA) that is capable of being enabled in a relatively quick fashion so as to amplify an incoming signal when needed, and then being disabled to set the LNA in a low power consumption mode. In particular, the LNA includes a pair of complimentary devices, and an enable circuit adapted to quickly cause the complimentary devices to conduct substantially the same current. In another aspect, a bias voltage generating apparatus is provided that uses a residual voltage from a prior operation to establish the current bias voltage for the LNA. In particular, the apparatus includes a controller adapted to tune an adjustable capacitor to a capacitance based on a residual voltage applied to a fixed capacitor, and couple the capacitors together to establish the bias voltage.

Claims

1. An apparatus, comprising:

a first circuit including first and second complimentary devices having inputs coupled together and outputs coupled together; and

a second circuit including at least a portion thereof coupled between the inputs and outputs of the complimentary devices, wherein the second circuit is adapted to cause the complimentary devices to conduct substantially the same current if the first circuit is enabled.

2. The apparatus of claim 1, further comprising a third circuit adapted to establish a specified voltage at the inputs or outputs of the complimentary devices if the first circuit is disabled.

3. The apparatus of claim 2, wherein the second or third circuit is adapted to be responsive to a control signal for enabling or disabling the first circuit.

4. The apparatus of claim 3, wherein the second and third circuits are configured to enable the first circuit within a specified time constant.

5. The apparatus of claim 1, wherein the second circuit is adapted to remove charges from the inputs of the complimentary devices to cause the complimentary devices to conduct substantially the same current.

6. The apparatus of claim 1, wherein the second circuit is adapted to route charges to the inputs of the complimentary devices to cause the complimentary devices to conduct substantially the same current.

7. The apparatus of claim 1, wherein the complimentary devices comprise a p-channel field effect transistor (FET) and an n-channel field effect transistor (FET).

8. The apparatus of claim 1, wherein the first circuit comprises a low noise amplifier (LNA).

9. The apparatus of claim 1, wherein the second circuit comprises a resistive element coupled in series with a controllable switch.

10. The apparatus of claim 2, wherein the third circuit comprises a controllable switch situated between a source of the specified voltage and the inputs or outputs of the complimentary devices.

11. A method of processing an input signal, comprising:

processing the input signal using a pair of complimentary devices having inputs coupled together and outputs coupled together; and

coupling the inputs to the outputs of the devices to cause the devices to conduct substantially the same current to enable the processing of the input signal.

12. The method of claim 11, further comprising establishing a specified voltage at the inputs or outputs of the complimentary devices to disable the processing of the input signal.

13. The method of claim 12, wherein establishing the specified voltage at the inputs or outputs of the complimentary devices is in response to a control signal indicating whether to enable or disable the processing of the input signal.

14. The method of claim 11, further comprising enabling the processing of the input signal within a specified time constant.

15. The method of claim 11, further comprising removing charges from the inputs of the complimentary devices to cause the complimentary devices to conduct substantially the same current.

16. The method of claim 11, further comprising routing charges to the inputs of the complimentary devices to cause the complimentary devices to conduct substantially the same current.

17. The method of claim 11, wherein the complimentary devices comprise a p-channel field effect transistor (FET) and an n-channel field effect transistor (FET).

18. An apparatus, comprising:

means for processing an input signal with a pair of complimentary devices having inputs coupled together and outputs coupled together; and

means for coupling together the inputs and outputs of the complimentary devices, wherein the coupling means is adapted to cause the complimentary devices to conduct substantially the same current if the processing means is enabled.

19. The apparatus of claim 18, further comprising means for establishing a specified voltage at the inputs or outputs of the complimentary devices if the processing means is disabled.

20. The apparatus of claim 19, wherein the specified voltage establishing means is adapted to be responsive to a control signal for enabling or disabling the processing means.

21. The apparatus of claim 18, wherein the coupling means is configured to enable the processing means within a specified time constant.

22. The apparatus of claim 18, wherein the coupling means is adapted to remove charges from the inputs of the complimentary devices to cause the complimentary devices to conduct substantially the same current.

23. The apparatus of claim 18, wherein the coupling means is adapted to route charges to the inputs of the complimentary devices to cause the complimentary devices to conduct substantially the same current.

24. The apparatus of claim 18, wherein the complimentary devices comprise a p-channel field effect transistor (FET) and an n-channel field effect transistor (FET).

25. The apparatus of claim 18, wherein the processing means is adapted to process the input signal having a fractional spectrum on the order of 20% or more, a spectrum on the order of 500 MHz or more, or a fractional spectrum on the order of 20% or more and a spectrum on the order of 500 MHz or more.

26. The apparatus of claim 18, wherein the processing means comprises a low noise amplifier (LNA).

27. The apparatus of claim 18, wherein the coupling means comprises a resistive element coupled in series with a controllable switch.

28. The apparatus of claim 19, wherein the specified voltage establishing means comprises a controllable switch situated between a source of the specified voltage and the inputs or outputs of the complimentary devices.

29. A headset, comprising:

a first circuit adapted to process a signal, wherein the first circuit comprises first and second complimentary devices having inputs coupled together and outputs coupled together; and

a second circuit coupled between the inputs and outputs of the complimentary devices, wherein the second circuit is adapted to cause the complimentary devices to conduct substantially the same current if the first circuit is enabled; and

a transducer adapted to generate sound based on the signal.

30. A watch, comprising:

a first circuit adapted to process a signal, wherein the first circuit comprises first and second complimentary devices having inputs coupled together and outputs coupled together; and

a second circuit coupled between the inputs and outputs of the complimentary devices, wherein the second circuit is adapted to cause the complimentary devices to conduct substantially the same current if the first circuit is enabled; and

a user interface adapted to provide an indication based on the signal.

31. A sensing device, comprising:

a first circuit adapted to process a signal, wherein the first circuit comprises first and second complimentary devices having inputs coupled together and outputs coupled together; and

a second circuit coupled between the inputs and outputs of the complimentary devices, wherein the second circuit is adapted to cause the complimentary devices to conduct substantially the same current if the first circuit is enabled; and

a sensor adapted to generate second data based on or in response to the signal.