3. TECHNICAL BRIEF. LG KG291, KG290

3. TECHNICAL BRIEF

3. TECHNICAL BRIEF

3.1 Power Amplifier (SKY77318, U500)

The SKY77318 Power Amplifier Module (PAM) is designed in a low profile (1.2 mm), compact form factor for quad-band cellular handsets comprising GSM850/900, DCS1800, and PCS1900 operation.

The PAM also supports Class 12 General Packet Radio Service (GPRS) multi-slot operation. The module consists of separate GSM850/900 PA and DCS1800/PCS1900 PA blocks, impedancematching circuitry for 50 Ω input and output impedances, and a Power Amplifier Control

(PAC) block with an internal current-sense resistor. The custom BiCMOS integrated circuit provides the internal PAC function and interface circuitry. Fabricated onto a single Gallium Arsenide (GaAs) die, one Heterojunction Bipolar Transistor (HBT) PA block supports the GSM850/900 bands and the other supports the DCS1800 and PCS1900 bands. Both PA blocks share common power supply pins to distribute current. The GaAs die, the Silicon (Si) die, and the passive components are mounted on a multi-layer laminate substrate. The assembly is encapsulated with plastic overmold. RF input and output ports of the SKY77318 are internally matched to a 50 Ω load to reduce the number of external components for a quad-band design. Extremely low leakage current (2.5 µA, typical) of the dual PA module maximizes handset standby time. The SKY77318 also contains band-select switching circuitry to select GSM (logic 0) or DCS/PCS (logic 1) as determined from the Band Select (BS) signal. In

Figure 1 below, the BS pin selects the PA output (DCS/PCS OUT or GSM850/900 OUT) and the

Analog Power Control (VAPC) controls the level of output power. The VBATT pin connects to an internal current-sense resistor and interfaces to an integrated power amplifier control (iPAC TM ) function, which is insensitive to variations in temperature, power supply, process, and input power. The

ENABLE input allows initial turn-on of PAM circuitry to minimize battery drain. Figure 1. Functional

Block Diagram

Figure1. Functional Block Diagram

Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes

- 15 LGE Internal Use Only

3. TECHNICAL BRIEF

SKY77318 PAM Pin Configuration-20-Pin

Leadless (Top View)

Figure 6. Typical Case Makings

12

13

14

15

10

11

8

9

16

17

18

19

6

7

4

5

Pin

1

2

3

20

GMD PAD

Mame

BS

VCC1A

DCS/PCS IN

GND IN

GND

VCC1B

GND

GND

GND

GND

GSM OUT

GND

GND

GND

Band Select

Description

VCC (to GSM 1st stage, DCS/PCS 1st stages, BiCMOS PAC)

RF input 1710-1910 MHz (DCS1800, PCS1900)

RF input 880-915 MHz (GSM)

RF and DC Ground

VCC (to GSM 2nd stage, DCS/PCS 2nd stages)

RF and DC Ground

RF and DC Ground

RF and DC Ground

RF and DC Ground

RF Output 880-915 MHz (GSM)

RF and DC Ground

RF and DC Ground

RF and DC Ground

DCS/PCS OUT RF Output 1710-1910 MHz (DCS 1800, PCS1900)

GND

VBATT

RF and DC Ground

Battery input to high side of intemal sense resistor

ENABLE

RSVD(GND)

BiCMOS Enable

RF and DC Ground

VAPC

GND

Power Control Bias Voltage

Ground Pad, device underside

Table 4. SKY77318 Pin Names and Signal Descriptions

LGE Internal Use Only - 16 Copyright © 2007 LG Electronics. Inc. All right reserved.

Only for training and service purposes