Granted Patent B2

US 7,409,198 · App. 11/214,061 · Granted Aug 5, 2008

Abstract

Claims (56)

1. A method in a receiver for applying a variable gain to a received signal including a transmitted codeword in accordance with an Ultra Wideband (UWB) protocol, the method comprising:

generating a first signal input to a selectable gain stage associated with the receiver, the first signal input including the received signal mixed with a local oscillator signal modified according to a reference codeword;

selecting a gain value from the selectable gain stage so as to amplify the first signal input to form a second signal input; and

generating an output signal by combining the second signal input and the local oscillator signal modified according to the reference codeword.

2. A method, as recited in claim 1 , wherein:

the selectable gain stage includes a bandpass filter stage; and

the selecting the gain value from the selectable gain stage includes filtering the first input signal with a bandpass stage, the filtering including:

setting a frequency response associated with the bandpass stage to a desired parameter;

simultaneously changing the frequency response and the gain value of the bandpass stage to a changed frequency response and a changed gain value so as to allow rapid settling when the selecting the gain value is performed; and

returning the frequency response from the changed frequency response to the desired parameter when the bandpass stage is settled at the changed gain value.

3. A method, as recited in claim 1 , wherein:

the selectable gain stage includes a plurality of selectable gain stages each having a respective bandpass filter stage; and

the selecting the gain value from the selectable gain stage includes selecting one of the plurality of selectable gain stages to form a selected one and filtering the first input signal with the respective bandpass stage associated with the selected one, the filtering including:

setting a frequency response associated with the respective bandpass stage to a desired parameter;

simultaneously changing the frequency response and the gain value of the respective bandpass stage to a changed frequency response and a changed gain value so as to allow rapid settling when the selecting the gain value is performed; and

returning the frequency response from the changed frequency response to the desired parameter when the respective bandpass stage is settled at the changed gain value.

4. A method, as recited in claim 1 , wherein a portion of the reference codeword is inverted, the reference codeword associated with the transmitted codeword.

5. A method, as recited in claim 1 , wherein a 50% portion of the reference codeword is inverted, the reference codeword associated with the transmitted codeword.

6. A method, as recited in claim 1 , wherein the UWB protocol includes a protocol in accordance with the Institute of Electrical and Electronic Engineering (IEEE) 802.15.3(a) specification.

7. A method as recited in claim 1 , wherein:

the selectable gain stage includes a 0 dB gain value and a 9 dB gain value; and

the selecting a gain value from the selectable gain stage includes selecting one of the 0 dB gain value and the 9 dB gain value.

8. A method in a direct conversion receiver for applying a variable gain to a received signal including a transmitted codeword in accordance with an Ultra Wideband (UWB) protocol on a signal path in the direct conversion receiver, the method comprising:

selecting a gain value of a Variable Gain Amplifier (VGA) associated with the direct conversion receiver and the variable gain;

setting a frequency response associated with a bandpass stage in the VGA to a desired parameter;

simultaneously changing the frequency response and the gain value of the bandpass stage to a changed frequency response and a changed gain value so as to allow rapid settling when the selecting the gain value is performed; and

returning the frequency response from the changed frequency response to the desired parameter when the bandpass stage is settled at the changed gain value.

9. A method, as recited in claim 8 , further comprising:

mixing the received signal including the transmitted codeword with a local oscillator signal including a reference codeword at a first point on the signal path before the VGA; and

mixing the local oscillator signal including the reference codeword with an amplified signal output from the VGA at a second point on the signal path after the VGA,

wherein a 50% portion the reference codeword is inverted.

10. A method, as recited in claim 8 , wherein VGA includes a plurality of selectable gain stages and wherein the selecting the gain value from the VGA includes selecting one of the plurality of selectable gain stages.

11. A method as recited in claim 10 , wherein:

each of the plurality of selectable gain stage includes a 0 dB gain value and a 9 dB gain value; and

the selecting the one of the plurality of selectable gain stages includes selecting one of the 0 dB gain value and the 9 dB gain values.

12. A method, as recited in claim 8 , wherein the UWB protocol includes a protocol in accordance with the Institute of Electrical and Electronic Engineering (IEEE) 802.15.3(a) specification.

13. An apparatus for applying a variable gain to a received signal including a codeword in accordance with an Ultra Wideband (UWB) protocol, the apparatus comprising:

an RF interface; and

a Variable gain amplifier (VGA) circuit coupled to the RF interface, the VGA circuit including:

a bandpass stage; and

a selectable gain stage coupled to the bandpass stage,

wherein the VGA circuit is configured to:

select a gain value of the selectable gain stage to form a selected gain;

set a frequency response associated with the bandpass stage to a desired parameter;

simultaneously change the frequency response and the gain value of the bandpass stage to a changed frequency response and a changed gain value so as to allow rapid settling when the selecting the gain value is performed; and

return the frequency response from the changed frequency response to the desired parameter when the bandpass stage is settled at the changed gain value.

14. An apparatus, as recited in claim 13 , wherein the VGA circuit is further configured to:

generate a first signal input to the bandpass stage and the selectable gain stage, the first signal input including the received signal mixed with a local oscillator signal modified according to a reference codeword;

select a gain value from the selectable gain stage so as to amplify the first signal input to form a second signal input; and

generate an output signal by combining the second signal input and the local oscillator signal modified according to the reference codeword.

15. An apparatus, as recited in claim 13 , wherein the selectable gain stage includes a plurality of selectable gain stages each selectable between one of 0 dB and 9 dB.

16. An apparatus, as recited in claim 13 , wherein the selectable gain stage includes a current mirror circuit having a selectable output current associated with the selected gain.

17. An apparatus, as recited in claim 13 , wherein the UWB protocol includes a protocol in accordance with the Institute of Electrical and Electronic Engineering (IEEE) 802.15.3(a) specification.

18. An apparatus, as recited in claim 13 , wherein:

the bandpass stage includes a first operational amplifier circuit having a first switchable feedback quantity to control a factor including the settling time of the bandpass stage; and

the selectable gain stage includes a second operational amplifier circuit having a second switchable resistance for the selecting the gain value.

Assignments (20)