DATA SHEET • SKY65066-360LF LOW NOISE AMPLIFIER

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com

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November 12, 2009 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 201090E

Table 1. SKY65066-360LF Signal Descriptions

Pin #

Name

Description

Pin #

Name

Description

1

BIAS1

5

FEEDBACK

Connect to RFOUT/VDD2 to reduce gain of

2

RFIN

RF input

6

N/C

No connection

3

N/C

No connection

7

RFOUT/VDD2

RF output. Requires a DC bias using an RF

choke inductor.

4

VDD1

8

BIAS2

Functional Description

The SKY65066-360LF is a two stage LNA with an integrated

interstage matching network and source inductors. The device

has a tested low NF of 0.7 dB and gain of 16.5 dB. The device

allows designers to adjust current and gain without degrading the

NF.

The external matching network largely dictates the RF

performance of the device. The matching network is required for

operation and special care should be taken when designing a

circuit board layout for the SKY65066-360LF. There are four

separate groups of external components: input, output, biasing,

and feedback.

Biasing

To properly bias a depletion mode pHEMT, both the gate and

recommended to ensure proper performance.

To eliminate the need for a negative DC supply, self-biasing

should be used when a resistor is placed between one of the

source leads and ground. A bypass capacitor should be placed in

parallel to this resistor to provide an RF ground and to ensure

performance remains unchanged at the operating frequency.

When current flows from drain to source and through the resistor,

the source voltage becomes biased above DC ground. The gate

pin of the device should be left unbiased at 0 V, which creates the

eliminating the need for a second DC supply. Values for resistor

components R1 and R2 can be changed to easily increase or

decrease the bias current to a desired level.

can be adjusted without degrading the overall NF. More current in

Biasing components R1, R2, C1, and C2 should be placed as

close to the package pins as possible. See Figure 12 for the

recommended board layout.

Source Inductance

The source inductance required on pins 1 and 8 (BIAS1 and BIAS2

signals, respectively) has been integrated on the die. This

simplifies board layout and reduces build variations.

Input and Output RF Matching Network

The input band-pass matching network consists of four

components. Component C1 serves as the input DC blocking

capacitor, C2 provides high frequency stability and improved input

return loss, and L1 and L2 are responsible for the best noise

match looking into the gate of the first stage amplifier.

Excess board trace should be eliminated at the input of the device

to minimize board losses. High-Q components should be used to

achieve the best NF of the amplifier. Murata GJM series

capacitors and Coilcraft HP or CS series inductors are

recommended. Any excess board or component loss on the input

of the device directly adds to the total measured NF.

The output matching network is band-pass network optimized for

output return loss.

The SKY65066-360LF Evaluation Board assembly diagram is

shown in Figure 13 and a circuit schematic is provided in

Figure 14.

Feedback

stage transistor. Feedback improves the input and output return

loss and high frequency stability. The gain of the device can be

increased by increasing the value of R3, which reduces the

amount of feedback present (gain for multiple feedback resistor

values is shown in Figure 12).