# US 2013/0278333 A1 · Optimizing cascade gain stages in a communication system

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2013/0278333 A1
- Document ID: US20130278333A1
- Status: Published application
- Kind: A1
- Application number: 13/449,956
- Filed: 2012-04-18
- Published: 2013-10-24
- Earliest claimed: 2012-04-18
- Assignees: Qualcomm Atheros, Inc.
- Inventors: Celestino A. CORRAL
- Web page: https://patentgrep.com/patent/US20130278333A1

## CPC

- H03F 3/602: {Combinations of several amplifiers}
- H03G 3/3052: {in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver (H03G3/32, H03G3/34 take precedence)}
- H03F: AMPLIFIERS
- H03G: CONTROL OF AMPLIFICATION

## Abstract

Techniques for optimizing a cascade gain device comprising at least two gain stages are disclosed. A first noise figure associated with the first gain stage is incrementally increased by a plurality of noise figure increments determined based, at least in part, on a minimum noise figure and a maximum noise figure associated with the first gain stage. At each of the plurality of noise figure increments, at least a gain value that corresponds to the noise figure increment is calculated. One of the plurality of noise figure increments and the corresponding gain value is selected as an optimum noise figure of the first gain stage and an optimum gain value of the first gain stage respectively. Parameters of an inter-stage matching network associated with the first gain stage are configured based on the optimum noise figure and the optimum gain of the first gain stage.

## Claims

### Claim 1

A method for optimizing a cascade gain device, the method comprising:
determining a first noise figure and a first gain associated with a first gain stage of the cascade gain device, wherein the cascade gain device comprises at least the first gain stage and a second gain stage;
incrementally increasing the first noise figure of the first gain stage by a plurality of noise figure increments, wherein the noise figure increments are determined based, at least in part, on a minimum noise figure and a maximum noise figure associated with the first gain stage;
at each of the plurality of noise figure increments, calculating at least a gain value that corresponds to the noise figure increment;
selecting one of the plurality of noise figure increments and the corresponding gain value as an optimum noise figure of the first gain stage and an optimum gain value of the first gain stage respectively; and
configuring one or more parameters of an inter-stage matching network associated with the first gain stage based on the optimum noise figure of the first gain stage and the optimum gain of the first gain stage.

### Claim 2 (depends on 1)

The method of claim 1, wherein said selecting one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage is based on at least one of a cascade noise figure associated with the cascade gain device or a cascade gain value associated with the cascade gain device.

### Claim 3 (depends on 1)

The method of claim 1, wherein the inter-stage matching network associated with the first gain stage is coupled between the first gain stage and the second gain stage of the cascade gain device.

### Claim 4 (depends on 1)

The method of claim 1, wherein at each of the plurality of noise figure increments, calculating at least the gain value that corresponds to the noise figure increment comprises:
at each of the plurality of noise figure increments, calculating the gain value and a source reflection coefficient that corresponds to the noise figure increment.

### Claim 5 (depends on 4)

The method of claim 4, wherein said configuring one or more parameters of the inter-stage matching network associated with the first gain stage based on the optimum noise figure of the first gain stage and the optimum gain of the first gain stage further comprises:
selecting the source reflection coefficient that corresponds to the optimum noise figure of the first gain stage as an optimum source reflection coefficient of the first gain stage;
calculating a load reflection coefficient of the first gain stage based, at least in part, on the optimum source reflection coefficient of the first gain stage; and
adjusting the one or more parameters of the inter-stage matching network based, at least in part, on the optimum source reflection coefficient and the load reflection coefficient of the first gain stage to achieve the optimum noise figure of the first gain stage and the optimum gain of the first gain stage.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first noise figure is the minimum noise figure associated with the first gain stage.

### Claim 7 (depends on 1)

The method of claim 1, wherein the second gain stage is associated with a second noise figure, wherein the second gain stage follows the first gain stage, wherein the second noise figure of the second gain stage is greater than the first noise figure of the first gain stage, wherein the second noise figure of the second gain stage satisfies:
F
2
≥
(
b
b
-
1
)

(
a
-
1
)

G
1

F
1
+
1
where,
F1 is the first noise figure of the first gain stage;
G1 is the first gain of the first gain stage;
F2 is the second noise figure of the second gain stage;
a is an increase in the first noise figure of the first gain stage; and
b is an increase in gain of the first gain stage resulting from the increase in the first noise figure of the first gain stage.

### Claim 8 (depends on 1)

The method of claim 1, wherein said selecting one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively comprises:
identifying one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively to optimize the cascade gain device such that the cascade gain device is associated with a minimum cascade noise figure and a cascade gain that is greater than or equal to an initial cascade gain.

### Claim 9 (depends on 8)

The method of claim 8, further comprising selecting the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage to satisfy:
aF
1
+
F
2
-
1
bG
1
=
minimum


cascade


noise


figure
wherein,
F1 is the first noise figure associated with the first gain stage;
G1 is the first gain associated with the first gain stage;
F2 is a second noise figure associated with the second gain stage;
a is an increase in the first noise figure of the first gain stage; and
b is an increase in gain of the first gain stage resulting from the increase in the first noise figure of the first gain stage.

### Claim 10 (depends on 1)

The method of claim 1, wherein said selecting one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively comprises:
selecting one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively to optimize the cascade gain device such that the cascade gain device is associated with a maximum cascade gain and a cascade noise figure that is less than or equal to the an initial cascade noise figure.

### Claim 11 (depends on 10)

The method of claim 10, wherein the initial cascade noise figure of the cascade gain device is calculated as a sum of the first noise figure of the first gain stage and a noise figure contribution from the second gain stage when the first gain stage is operating at the first noise figure.

### Claim 12 (depends on 11)

The method of claim 11, further comprising selecting the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage to satisfy:
aF
1
+
F
2
-
1
bG
1
=
F
1
+
F
2
-
1
G
1
wherein,
F1 is the first noise figure associated with the first gain stage;
G1 is the first gain associated with the first gain stage;
F2 is a second noise figure associated with the second gain stage;
a is an increase in the first noise figure of the first gain stage; and
b is an increase in gain of the first gain stage resulting from the increase in the first noise figure of the first gain stage.

### Claim 13 (depends on 1)

The method of claim 1, wherein if the cascade gain device comprises a third gain stage following the second gain stage, the method further comprises:
designating a combination of the first gain stage and the second gain stage as a combined gain stage; and
executing optimization operations for the combined gain stage and the third gain stage to optimize the cascade gain device.

### Claim 14 (depends on 1)

The method of claim 1, further comprising:
determining a stability factor associated with the first gain stage based, at least in part, on one or more device parameters of the first gain stage;
determining whether the stability factor associated with the first gain stage satisfies a predetermined stability threshold;
in response to determining that the stability factor associated with the first gain stage satisfies the predetermined stability threshold, executing optimization operations for the cascade gain device by said incrementally increasing the first noise figure of the first gain stage by the plurality of noise figure increments; and
in response to determining that the stability factor associated with the first gain stage does not satisfy the predetermined stability threshold, determining not to execute the optimization operations for the cascade gain device.

### Claim 15 (depends on 14)

The method of claim 14, wherein the device parameters of the first gain stage comprise scattering (S) parameters of the first gain stage, the minimum noise figure associated with the first gain stage, a source reflection coefficient that corresponds to the minimum noise figure, and a noise resistance of the first gain stage, wherein at least one of the device parameters is associated with the bias condition.

### Claim 16 (depends on 15)

The method of claim 15, further comprising:
varying the bias condition associated with the first gain stage to vary at least one device parameter associated with the first gain stage; and
executing optimization operations for the cascade gain device by said incrementally increasing the first noise figure of the first gain stage by the plurality of noise figure increments in response to said varying the bias condition associated with the first gain stage.

### Claim 17 (depends on 1)

The method of claim 1, wherein the first gain stage comprises one or more of an amplifier, a filter unit, and a mixer unit, and the second gain stage comprises one or more of an amplifier, a filter unit, and a mixer unit.

### Claim 18 (depends on 1)

The method of claim 1, wherein said selecting one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively further comprises:
selecting the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively such that a stability factor associated with the first gain stage satisfies a predetermined stability threshold, wherein the stability factor is determined based, at least in part, on one or more device parameters of the first gain stage.

### Claim 19

A communication device comprising:
a cascade gain device comprising at least a first gain stage and a second gain stage;
an inter-stage matching network associated with the first gain stage; and
an optimization unit coupled with the cascade gain device and the inter-stage matching network, the optimization unit operable to:
determine a first noise figure and a first gain associated with the first gain stage of the cascade gain device;
incrementally increase the first noise figure of the first gain stage by a plurality of noise figure increments, wherein the noise figure increments are determined based, at least in part, on a minimum noise figure and a maximum noise figure associated with the first gain stage;
calculate, at each of the plurality of noise figure increments, at least a gain value that corresponds to the noise figure increment;
select one of the plurality of noise figure increments and the corresponding gain value as an optimum noise figure of the first gain stage and an optimum gain value of the first gain stage respectively; and
configure one or more parameters of the inter-stage matching network associated with the first gain stage based on the optimum noise figure of the first gain stage and the optimum gain of the first gain stage.

### Claim 20 (depends on 19)

The communication device of claim 19, wherein the inter-stage matching network associated with the first gain stage is coupled between the first gain stage and the second gain stage of the cascade gain device.

### Claim 21 (depends on 19)

The communication device of claim 19,
wherein, the optimization unit operable to calculate, at each of the plurality of noise figure increments at least the gain value that corresponds to the noise figure increment comprises the optimization unit operable to:
calculate, at each of the plurality of noise figure increments, the gain value and a source reflection coefficient that corresponds to the noise figure increment; and
wherein the optimization unit operable to configure one or more parameters of the inter-stage matching network associated with the first gain stage based on the optimum noise figure of the first gain stage and the optimum gain of the first gain stage further comprises the optimization unit operable to:
select the source reflection coefficient that corresponds to the optimum noise figure of the first gain stage as an optimum source reflection coefficient of the first gain stage;
calculate a load reflection coefficient of the first gain stage based, at least in part, on the optimum source reflection coefficient of the first gain stage; and
adjust the one or more parameters of the inter-stage matching network based, at least in part, on the optimum source reflection coefficient and the load reflection coefficient of the first gain stage to achieve the optimum noise figure of the first gain stage and the optimum gain of the first gain stage.

### Claim 22 (depends on 19)

The communication device of claim 19, wherein the optimization unit operable to select one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively comprises the optimization unit operable to:
identify one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively to optimize the cascade gain device such that the cascade gain device is associated with a minimum cascade noise figure and a cascade gain that is greater than or equal to an initial cascade gain.

### Claim 23 (depends on 19)

The communication device of claim 19, wherein the optimization unit operable to select one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively comprises the optimization unit operable to:
select one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively to optimize the cascade gain device such that the cascade gain device is associated with a maximum cascade gain and a cascade noise figure that is less than or equal to the an initial cascade noise figure.

### Claim 24 (depends on 19)

The communication device of claim 19, wherein if the cascade gain device comprises a third gain stage following the second gain stage, the optimization unit is further operable to:
designate a combination of the first gain stage and the second gain stage as a combined gain stage; and
execute optimization operations for the combined gain stage and the third gain stage to optimize the cascade gain device.

### Claim 25 (depends on 19)

The communication device of claim 19, wherein the optimization unit is further operable to:
determine a stability factor associated with the first gain stage based, at least in part, on one or more device parameters of the first gain stage;
determine whether the stability factor associated with the first gain stage satisfies a predetermined stability threshold;
execute optimization operations for the cascade gain device by incrementally increasing the first noise figure of the first gain stage by the plurality of noise figure increments in response to the optimization unit determining that the stability factor associated with the first gain stage satisfies the predetermined stability threshold; and
determine not to execute the optimization operations for the cascade gain device in response to the optimization unit determining that the stability factor associated with the first gain stage does not satisfy the predetermined stability threshold.

### Claim 26

One or more machine-readable storage media having instructions stored therein, which when executed by one or more processors causes the one or more processors to perform operations that comprise:
determining a first noise figure and a first gain associated with a first gain stage of a cascade gain device, wherein the cascade gain device comprises at least the first gain stage and a second gain stage;
incrementally increasing the first noise figure of the first gain stage by a plurality of noise figure increments, wherein the noise figure increments are determined based, at least in part, on a minimum noise figure and a maximum noise figure associated with the first gain stage;
at each of the plurality of noise figure increments, calculating at least a gain value that corresponds to the noise figure increment;
selecting one of the plurality of noise figure increments and the corresponding gain value as an optimum noise figure of the first gain stage and an optimum gain value of the first gain stage respectively based on at least one of a cascade noise figure associated with the cascade gain device and a cascade gain value associated with the cascade gain device; and
configuring one or more parameters of an inter-stage matching network associated with the first gain stage based on the optimum noise figure of the first gain stage and the optimum gain of the first gain stage

### Claim 27 (depends on 26)

The machine-readable storage media of claim 26,
wherein at each of the plurality of noise figure increments, said operation of calculating at least the gain value that corresponds to the noise figure increment comprises:
at each of the plurality of noise figure increments, calculating the gain value and a source reflection coefficient that corresponds to the noise figure increment; and
wherein said operation of configuring one or more parameters of the inter-stage matching network associated with the first gain stage based on the optimum noise figure of the first gain stage and the optimum gain of the first gain stage further comprises:
selecting the source reflection coefficient that corresponds to the optimum noise figure of the first gain stage as an optimum source reflection coefficient of the first gain stage;
calculating a load reflection coefficient of the first gain stage based, at least in part, on the optimum source reflection coefficient of the first gain stage; and
adjusting the one or more parameters of the inter-stage matching network based, at least in part, on the optimum source reflection coefficient and the load reflection coefficient of the first gain stage to achieve the optimum noise figure of the first gain stage and the optimum gain of the first gain stage.

### Claim 28 (depends on 26)

The machine-readable storage media of claim 26, wherein said operation of selecting one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively comprises one of:
identifying one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively to optimize the cascade gain device such that the cascade gain device is associated with a minimum cascade noise figure and a cascade gain that is greater than or equal to an initial cascade gain, or
selecting one of the plurality of noise figure increments and the corresponding gain value as the optimum noise figure of the first gain stage and the optimum gain value of the first gain stage respectively to optimize the cascade gain device such that the cascade gain device is associated with a maximum cascade gain and a cascade noise figure that is less than or equal to the an initial cascade noise figure.