System and method of using residual voltage from a prior operation to establish a bias voltage for a subsequent operation

• US 8,275,343 B2
• Filed: 03/10/2008
• Issued: 09/25/2012
• Est. Priority Date: 03/10/2008
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Fagg, Russell John
• Primary Examiner(s): Ghebretinsae, Temesgh
• Assistant Examiner(s): Tsvey, Gennadiy
• Application Number:
  US12/045,592
• Publication Number:
  US 20090224860A1
• Time in Patent Office: 1,660 Days
• Field of Search: 455/343.1, 455/231
• US Class Current: 455/343.1
• 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 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/507 A switch being used for switching on or off a supply or supplying circuit in an IC-block amplifier circuit
• CPC Class Codes: H03F 2200/511 Many discrete supply voltages or currents or voltage levels can be chosen by a control signal in an IC-block amplifier circuit
• CPC Class Codes: H03F 2203/30031 A resistor being coupled as feedback circuit in the SEPP amplifier
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/3022 CMOS common source output SEPP amplifiers H03F3/3008 takes precedence
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H04B 2001/6908 using time hopping

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 capacitive element;

a second capacitive element;

a load adapted to draw current from the first capacitive element causing a second voltage across the first capacitive element to change to a first voltage;

a controller adapted to;

tune the second capacitive element to a capacitance based on the first voltage across the first capacitive element;

couple a source of a third voltage to the first capacitive element in response to a first timing signal to generate a fourth voltage across the first capacitive element, wherein the fourth voltage is between the first and second voltages; and

couple the tuned second capacitive element with the first capacitive element in response to a second timing signal to re-establish the second voltage across the first capacitive element.

2. The apparatus of claim 1, further comprising a timing generator adapted to generate the first and second timing signals.

3. The apparatus of claim 1, wherein the controller is adapted to generate a fifth voltage across the second capacitive element.

4. The apparatus of claim 1, wherein the load comprises a receiver including one or more components adapted to operate in response to the second voltage.

5. The apparatus of claim 4, wherein the one or more components of the receiver includes a low noise amplifier (LNA).

6. The apparatus of claim 5, wherein the one or more components of the receiver include an enable circuit for the LNA.

7. The apparatus of claim 1, wherein the load comprises a transmitter including one or more components adapted to operate in response to the second voltage.

8. A method of operating an apparatus, comprising:

enabling a load to draw current from a first capacitive element causing a second voltage across the first capacitive element to change to a first voltage;

tuning a second capacitive element to a capacitance based on the first voltage;

coupling a source of a third voltage to the first capacitive element in response to a first timing signal to generate a fourth voltage across the first capacitive element, wherein the fourth voltage is between the first and second voltages; and

coupling the tuned second capacitive element with the first capacitive element in response to a second timing signal to re-establish the second voltage across the first capacitive element.

9. The method of claim 8, further comprising generating a fifth voltage across the second capacitive element.

10. The method of claim 8, further comprising processing, by the load, an input signal using one or more components adapted to operate in response to the second voltage.

11. An apparatus, comprising:

means for enabling a load to draw current from a first capacitive element causing a second voltage across the first capacitive element to change to a first voltage;

means for tuning a second capacitive element to a capacitance based on the first voltage;

means for coupling a source of a third voltage to the first capacitive element in response to a first timing signal to generate a fourth voltage across the first capacitive element, wherein the fourth voltage is between the first and second voltages; and

means for coupling the tuned second capacitive element with the first capacitive element in response to a second timing signal to re-establish the second voltage across the first capacitive element.

12. The apparatus of claim 11, further comprising means for generating the first and second timing signals.

13. The apparatus of claim 11, further comprising means for generating a fifth voltage across the second capacitive element.

14. The apparatus of claim 11, wherein the load comprises means for processing an input signal using one or more components adapted to operate in response to the second voltage.

15. The apparatus of claim 14, wherein the one or more components of the processing means includes a low noise amplifier (LNA).

16. The apparatus of claim 15, wherein the one or more components of the processing means includes an enable circuit for the LNA.

17. The apparatus of claim 11, wherein the load comprises a transmitter including one or more components adapted to operate in response to the second voltage.

18. The apparatus of claim 14, wherein the input signal has 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.

19. A headset, comprising:

a transducer adapted to generate data;

a first capacitive element;

a device adapted to process the data by drawing current from the first capacitive element causing a second voltage across the first capacitive element to change to a first voltage;

a second capacitive element; and

a controller adapted to;

tune the second capacitive element to a capacitance based on the first voltage across the first capacitive element;

couple a source of a third voltage to the first capacitive element in response to a first timing signal to generate a fourth voltage across the first capacitive element, wherein the fourth voltage is between the first and second voltages; and

couple the tuned second capacitive element with the first capacitive element in response to a second timing signal to re-establish the second voltage for the device.

20. A watch, comprising:

a first capacitive element;

a receiver adapted to process data by drawing current from the first capacitive element causing a second voltage across the first capacitive element to change to a first voltage;

a user interface adapted to provide an indication based on the data; and

a second capacitive element; and

a controller adapted to;

tune the second capacitive element to a capacitance based on the first voltage across the first capacitive element;

couple a source of a third voltage to the first capacitive element in response to a first timing signal to generate a fourth voltage across the first capacitive element, wherein the fourth voltage is between the first and second voltages; and

couple the tuned second capacitive element with the first capacitive element in response to a second timing signal to re-establish the second voltage for one or more components of the receiver.

21. A sensing device, comprising:

a first capacitive element;

a sensor adapted to generate data;

a transmitter adapted to transmit the data by drawing current from the first capacitive element causing a second voltage across the first capacitive element to change to a first voltage; and

a second capacitive element; and

a controller adapted to;

tune the second capacitive element to a capacitance based on the first voltage across the first capacitive element;

couple a source of a third voltage to the first capacitive element in response to a first timing signal to generate a fourth voltage across the first capacitive element, wherein the fourth voltage is between the first and second voltages; and

couple the tuned second capacitive element with the first capacitive element in response to a second timing signal to re-establish the second voltage for one or more components of the transmitter.