APPLICATION NOTE SKY77354 Power Amplifier … Tx Signal 850 / 900 MHz 4 PA_ON2 Low Band Enable 5 PA_ON3 High Band Enable 6 VMODE0 Control Voltage for Mode Setting 7 VBATT Battery supply

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202533A • Skyworks Proprietary and Confidential Information. • Products and product information are subject to change without notice. • November 16, 2012 1

APPLICATION NOTE

SKY77354 Power Amplifier Module – Evaluation Board Information Applicability: SKY77354 Power Amplifier Module for Quad-Band GSM/ GPRS/ EDGE

Introduction This Application Note provides the customer with information that will assist in the evaluation of the SKY77354 Power Amplifier Module (PAM). This includes information in device functionality, use of the evaluation board (EN40-D305-002), and helpful application instructions.

The SKY77354 is designed for quad-band cellular handsets comprising GSM850/900, DCS1800, and PCS1900. The PAM also supports fixed gain Gaussian Minimum-Shift Keying (GMSK), and linear Enhanced Data for GSM Evolution (EDGE) modulation, including Class 12 General Packet Radio Service (GPRS) multi-slot operation. Two fixed-gain power modes are available for GSM850/900 bands and DCS1800/PCS1900 bands.

The PAM consists of an InGaP/GaAs PA block, impedance-matching circuitry, and a Multifunction (MFC) block. Embedded

within a single Gallium Arsenide (GaAs) die using InGaP technology is one Heterojunction Bipolar Transistor (HBT) PA block to support the GSM850/900 bands and a second block to support the DCS1800 and PCS1900 bands. Both PA blocks share common power supply pads to distribute current. The MFC block, implemented with BiCMOS IC, provides on-chip logic for PA enable and mode switch control, and on-chip voltage regulation for PA biasing. The on-chip voltage regulator eliminates external PA biasing.

Band select switching circuitry selects the GSM and DCS/PCS bands which is determined from the PA_ON2 and PA_ON3 signals. The VMODE0 control can change the mode of operation to High Power or Low Power mode for the desired output power level. Each power mode is identified with certain fixed amplifier gain and for both modes of operation; input power controls the output power level for GMSK and EDGE modulation.

FIGURE 1. SKY77354 FUNCTIONAL BLOCK DIAGRAM

APPLICATION NOTE SKY77354 POWER AMPLIFIER MODULE — EVALUATION BOARD INFORMATION

Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 2 November 16, 2012 • Skyworks Proprietary and Confidential Information. • Products and product information are subject to change without notice. • 202533A

FIGURE 2. SKY77354 PAD CONFIGURATION – TOP VIEW

TABLE 1. PAD SIGNAL NAMES AND FUNCTIONS Pad1 Signal Function

1 HB_GSM_RF_IN Input Tx Signal 1800 / 1900 MHz

3 LB_GSM_RF_IN Input Tx Signal 850 / 900 MHz

4 PA_ON2 Low Band Enable

5 PA_ON3 High Band Enable

6 VMODE0 Control Voltage for Mode Setting

7 VBATT Battery supply voltage

8 LB_GSM_RF_OUT Output Tx signal 850 / 900 MHz

11 HB_GSM_RF_OUT Output Tx signal 1800 / 1900 MHz

14 V2G Supply voltage

GROUND PAD Segmented Ground Pad is device underside 1 Pads 2, 9, 10, 12, 13 are Ground (GND) pads.

Operational Considerations The SKY77354 is intended for multi-modulation GSM/GPRS/EDGE handset. The following section describes how the module should be configured for such operation.

GSM/GPRS/EDGE Operation

The module operates in a linear open loop configuration with POUT controlled by the input power, PIN. Output power is defined as:

POUT = PIN + Gain

An example of Gain versus POUT curves with respect to different modes of operation can be seen in Figure 2. Control logic for the modes of operation is shown in Table 1.

To operate, select the desired TX band by setting PA_ON2 high and PA_ON3 low for CELL/EGSM or PA_ON2 low and PA_ON3

high for DCS/PCS. For a desired output power, select the corresponding mode of operation by setting the relevant control logic for VMODE0. For example, to operate in High Power Mode for CELL/EGSM, set PA_ON2 high and PA_ON3 low, and set VMODE0 low.

Contrary to conventional GSM amplifier modules, operation with GSM/GPRS modulation is identical to conventional operation method with modulation. An internal voltage regulator sets up PA biasing so that no external voltage biasing VRAMP is needed. Input power (PIN), provides the ramping profile and determines the output power (POUT) based on the chosen mode of operation.

The V2G pad connects to the collectors of the HBTs and sets up current to deliver output power. The VBATT pad connects to the internal biasing network to set up DC bias points for the HBTs.

FIGURE 3. SKY77354 GAIN VS. POWER OUTPUT – EXAMPLES UNDER DIFFERENT MODES OF OPERATION

SKY77354 POWER AMPLIFIER MODULE — EVALUATION BOARD INFORMATION APPLICATION NOTE


Control Logic/Mode of Operation

TABLE 2. CONTROL LOGIC

GMSK Mode of Operation PA_ON2 PA_ON3 VMODE0

Power Down Low Low x

High Isolation Low Low x

Low Band - High Power Mode (22.5 dBm < POUT ≤ 34.5 dBm) High Low Low

Low Band - Low Power Mode (POUT ≤ 24.5 dBm) High Low High

High Band - High Power Mode (22 dBm < POUT ≤ 32 dBm) Low High Low

High Band - Low Power Mode (POUT ≤ 24 dBm) Low High High

EDGE Mode of Operation LB_EN HB_EN VMODE0

Power Down Low Low x

High Isolation Low Low x

Low Band - High Power Mode (15 dBm < POUT ≤ 28 dBm) High Low Low

Low Band - Low Power Mode (POUT ≤ 15 dBm) High Low High

High Band - High Power Mode (14.5 < POUT ≤ 26.5 dBm) Low High Low

High Band - Low Power Mode (POUT ≤ 14.5 dBm) Low High High

X = Don't care

SKY77354 Evaluation Board (EVB) The evaluation board (EVB) assembly drawing in Figure 3 shows the placement of board components and their designations.

Not all components are installed on the evaluation board assembly. Capacitors C6, C7, C8, C13, C14, C15, and C16 are not normally installed; but mounting locations are provided to add capacitance to VBATT and control logics to insure good low frequency bypassing, depending on the quality of the bench power supply used. See the bill-of-material in Table 2 for

component descriptions, value ratings, and types. Individual board layers are shown in Figures 6 through 9.

NOTE: Not all the EVB bypass capacitor values are compatible with Switching Mode Power Supply (SMPS). See Table 2.

The circuit schematic of the evaluation board in Figure 4 illustrates the interconnections and board components in relation to the SKY77354 Power Amplifier Module.

TABLE 3. SKY77354 EVALUATION BOARD BILL OF MATERIAL

Item Quantity Reference Designator Part Description

1 2 C11, C12 Capacitor, 220 µF, TANTALUM1

2 3 C5, C9, C10 Capacitor, 10 µF TANTALUM1

3 1 C2 Capacitor, 0.01 µF, ±10%, X7R 0402

4 1 C4 Capacitor, 0.1 µF, ±10%, X7R 0402

5 1 C1, C3 Capacitor, 100 pF, ±5%, COG 0402

62 — C6, C7, C8, C13, C14, C15, C16, R1 DO NOT PLACE

1 These cap values are NOT SMPS-compatible. 2 These components are not normally installed on the EVB but are optional for additional supply and logic control filtering.



FIGURE 4. SKY77354 POWER AMPLIFIER TEST FIXTURE

FIGURE 5. SKY77354 POWER AMPLIFIER TEST FIXTURE SCHEMATIC



FIGURE 6. SKY77354 POWER AMPLIFIER TEST FIXTURE PCB LAYER 1












Layout Guidelines for Battery Bypassing Phone board layout is a complex issue, and one key area is supply decoupling. The transient current for VCC will be supported by the nearby capacitance. The VCC line of the PAM requires low frequency bypass capacitance. In modern communication systems, a GSM PA draws rapid pulses of current that can cause significant transients during the transmission. This might affect the output power mask at high power levels. Most lab supplies are not suited for digital communications and do not emulate the phone board battery condition. Hence, in some cases a higher value capacitor of 68 µF may be required. Figure 10 shows a

recommended application layout for SMPS compatible bypass capacitor values.

The value of bypass capacitor on VCC line should be no less than 100 pF to avoid potential Rx band noise spur issue. For low band RF input LB_GSM_RF_IN, high-pass filter placeholders between the transceiver and the PA are recommended in the event of insufficient noise margin around 700 MHz. Figure 10 is a recommended high pass T network.

Battery ESR will reduce the transient voltage pulse in the phone board and should not require more than a 10 µF bypass capacitor. The bypass capacitor should be a good quality ceramic or tantalum capacitor.

FIGURE 10. APPLICATION LAYOUT DIAGRAM FOR SKY77354 – SMPS COMPATIBLE COMPONENT VALUES



FIGURE 11. TRANSMIT TIMING DIAGRAM FOR GMSK MULTI-SLOT DIFFERENT POWER MODE OPERATION



FIGURE 12. TRANSMIT TIMING DIAGRAM FOR GMSK SINGLE-SLOT OPERATION

Ordering Information

Model Number Manufacturing Part Number

SKY77354 Evaluation Board EN40-D305-002

Revision History

Revision Date Description

A November 16, 2012 Initial Release

References Skyworks Data Sheet: SKY77354 Power Amplifier Module for Quad-Band GSM/ GPRS/ EDGE, Document Number 201526

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APPLICATION NOTE SKY77354 Power Amplifier … Tx Signal 850 / 900 MHz 4 PA_ON2 Low Band Enable 5 PA_ON3 High Band Enable 6 VMODE0 Control Voltage for Mode Setting 7 VBATT Battery supply