Adjustable, High-Linearity,

SiGe Dual-Band LNA/Mixer ICs

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17

Layout Considerations

Keep RF signal lines as short as possible to minimize

losses and radiation. Use high-Q components for the LNA

input matching circuit to achieve the lowest possible

noise figure. At the digital mixer outputs, keep the differ-

ential signal lines together and of equal length to ensure

signal balance. For best gain and noise performance, sol-

der the slug evenly to the board ground plane.

Table 5. Typical Cascaded Performance of Cellular-Band Receiver with 3dB Interstage

Filter Loss

Table 6. Typical Cascaded Performance of PCS-Band Receiver with 3dB Interstage

Filter Loss

PARAMETER

Conversion Power Gain

Noise Figure

Third-Order Input Intercept

HIGH GAIN,

HIGH LINEARITY

25.4dB

2.1dB

-8.9dBm

HIGH GAIN,

LOW LINEARITY

24.5dB

2.3dB

-10.6dBm

LOW GAIN,

HIGH LINEARITY

8.9dB

11.8dB

-6.8dBm

FM

22.7dB

3.3dB

-6.8dBm

-9.3dBm

-7.6dBm

7.1dBm

Third-Order Input Intercept

3.0dB

2.6dB

12.4dB

Noise Figure

PARAMETER

22.5dB

HIGH GAIN,

LOW LINEARITY

24dB

7.5dB

Conversion Power Gain

HIGH GAIN,

HIGH LINEARITY

LOW GAIN

Table 7. Cellular LNA S Parameters in High-Gain, High-Linearity Mode

0.109

59.1

0.669

-40.8

0.496

1000

-90.6

3.3

74.9

0.104

58.3

0.674

-39.3

0.503

950

-88.5

3.5

76.6

0.099

58.8

0.677

-38.3

0.51

900

-86.1

3.7

79.4

0.096

60.1

0.683

-37.6

0.52

850

-83.7

3.88

81.9

0.0908

60

0.689

0.089

60.6

-36.6

0.696

-35.9

0.714

S22

(mag)

-34.7

0.085

S12

(mag)

60.9

S22

(phase)

S12

(phase)

0.534

800

-81.2

4.13

0.548

750

-78.4

84.4

4.39

87.9

4.63

S21

(mag)

92.1

0.579

S11

(mag)

700

-74.8

S21

(phase)

FREQUENCY

(MHz)

S11

(phase)