CDMA/EVDO and WCDMA/HSPA are the two technologies with the widest range of 3G deployments. These two technologies rely on Code Division Multiple Access (CDMA) digital wireless technology, enabling many users to efficiently utilize voice and data communications in the same RF spectrum. CDMA is a type of spread spectrum RF communication that is assigned to each user by a unique "cut code" to distinguish other users in the same RF spectrum. Spectrum expansion increases channel capacity and allows multiple users to use the carrier's full bandwidth. CDMA/EVDO network operators use 1.25MHz, while WCDMA/HSPA networks utilize a wider range of 5MHz. The data transfer rate can further increase high-order modulation in the wireless network to provide a better user experience and wireless data. This article refers to the address: http:// Multi-band CDMA and WCDMA handsets require greater RF design work to provide adequate output power and ensure linearity and efficiency in normal operation of each frequency band. The design typically includes a power amplifier and duplex, RF filters and switches that facilitate each frequency band to accommodate multiple RF inputs to a single antenna. In order to reduce the complexity of multi-band handset design, ANADIGICS has developed dual-band CDMA and WCDMA power amplifier modules. By integrating two power amplifier modules in a single package, board area can be effectively reduced compared to previous DC and RF signal line designs using two separate power amplifiers. This article describes the typical application of dual-band power amplifier modules in CDMA/EVDO and WCDMA/HSPA handset designs. ANANDIGICS' AWT6221 has won the Outstanding Achievement Award for Information Technology Application and Communication Technology Innovation issued by the Ministry of Industry and Information Technology of China. ANADIGICS' HELP3 amplifiers, such as the AWT6221 power amplifier, use the company's proprietary InGaP-Plus technology to integrate HBT and pHEMT devices in the same BiFET wafer. With an optional bias mode, the HELP3 power amplifier exhibits optimum efficiency in both low and mid output power levels. The intelligent bias circuit's AWT6221 reduces current consumption to 8mA at low power levels. By integrating two separate power amplifier chains, the ultra-mini AWT6221 delivers superior performance in both frequency bands and saves printed circuit board area, as shown in Figure 1. Figure 1. AWT6221 reference design Most frequency division duplex systems for CDMA and WCDMA networks allow different RF bands to be assigned to the uplink (from mobile to base station) and downstream (from base station to mobile). Duplexers are used in mobile devices to allow UL and DL to utilize a single antenna. In UMTS Band 2, we chose Avago Technology's miniature FBAR duplex high Q response ACMD-7403. For Band 5, we chose the Epcos low-loss SAW duplex B-7663. The reference design also includes the coupled AVX of the CP402A thin film power directional coupler to provide the required RF power for many top 3G chipsets. Figure 3. Cell Band: PA output to Antenna Port without Matching Figure 4. PCS Band: PA output to Antenna Port with(out) Match Figure 7. Cell Band: PA output to Antenna Port after Duplexer to Antenna optimization Figure 8. PCS Band : PA output to Antenna Port with(out) Match Figure 8. PCS Band : PA output to Antenna Port with(out) Match Figure 10. PCS Band: PA Load optimization Figure 12. PCS ACPR performance Over Temperature and Voltage ANADIGICS' AWT6221 is one of a family of dual-band power amplifiers in 3G handsets and data devices. The current ANADIGICS dual-band power amplifier products are listed below, and new designs are being developed. Ware Resistance Lining Ceramics Ware Resistance Lining Ceramics,Alumina Tile Plat,Ware Ceramic Liner,Alumina Tiles Plate Yixing Guangming Special Ceramics Co.,Ltd , https://www.yxgmtc.com
Compared to a standard power amplifier, the AWT6221 dual-band power amplifier significantly reduces average current consumption by up to 75% and increases talk time by up to 25%. 
The AWT6221 was developed for dual-band WCDMA/HSPA handsets UMTS Band 2 (824-849MH) and Band 5 (1850 MHz to 1910MHz). The 3GPP technology specifies the power level of user equipment level 3, which must meet or exceed these minimum performance levels:
Maximum output power: +24dBm +1/-3 dBm
Adjacent channel leakage power ratio (ACLR) +/- 5MHz: -33dBm
Adjacent channel leakage power ratio (ACLR) +/- 10MHz: -43dBm
Maximum harmonic emission specified frequency:
30-1000MHz: -12dBm/100kHz between 1-12.75GHz: -30dBm/1MHz between 869-894MHz: -60dBm/3.84MHz between 1930-1990MHz: -60dBm/3.84MHz between 2100-2170MHz: -60dBm/ Between 3.84MHz
The development of the AWT6221 reference design begins with the measurement of the power amplifier's further coupling and duplex S-parameters. In this measurement, a zero ohm resistor is used to shorten the matching components on the board, see Figure 2. 
The S parameter describes the voltage signal that the N port responds to each port network. The subscript of the first number refers to the response port, while the second number refers to the event port. Therefore, S21 refers to the reaction of signal terminal 1 at port 2. The S parameter comes from a matrix port with the same number of rows and columns. The parameters along the diagonal of the S matrix are called reflection coefficients, and the diagonal S parameters are called transmission coefficients because they only occur on a single port. The two-port network of the S matrix is ​​shown in the following table: 
The reflection coefficient (S11) is tested for the frequency range of the band 2 and band 5 RF paths. The power amplifier forms a series of impedance changes at the output of the non-conforming circuit. The results are shown in the Smith table in Figures 3 and 4. 
For any power amplifier, the output impedance has a significant impact on operation and strongly affects the power transferred to the antenna, linear (ACLR) and operational efficiency. Power amplifiers like ANADIGICS manufacturers help engineers balance these load pull information. The optimum output impedance is affected by the characteristics of other RF chain components, such as duplexers and switches that are not always 50Ω. The advantages and operating temperatures in the frequency range of the variability frequency duplex feature are particularly challenging in well-developed WCDMA RF designs, see Figure 5 and Figure 6. 
Figure 5 
The next step in developing the AWT6221 reference design is to match the impedance of the duplex antenna to minimize the frequency of change in impedance in each band. Although simple two components theoretically have superior performance over narrowband frequencies, achieving good performance over a wider bandwidth and compensating for variations in production tolerances and temperatures, or predictable variables due to voltage, often require additional Compliance with the elements. The results of the 3 component selection for the two bands are shown in the Smith chart. The matched network greatly reduces the impedance variation under duplexing, which simplifies the remaining circuits that can be met, see Figure 7 and Figure 8. 
The next step in developing the AWT6221 reference design is the pairing between the power amplifier and the coupler + duplex. Again, for Band 2 and Band 5, a reflection of the frequency range of the RF path (S11) is shown in Figure 8; the final is to be used to develop a power amplifier that can be used in WCDMA operation with minimum impedance variation and optimized power. A network of amplifier performance requirements. As before, a 3-component network can achieve good performance; the results are shown in the Smith chart of Figures 9 and 10. 
Figure 9. Cell Band: PA Load optimization 
The final product reference design meets WCDMA requirements for Band 2 and Band 5 at room temperature. In addition, the matching network minimizes varying frequency, temperature and supply voltage under all expected ranges while still maintaining performance specifications, see Figures 11 and 12. 
Figure 11. Cell Band ACPR performance Over Temperature and Voltage 
The reference designs discussed in this article provide a useful starting point for newly designed 3G handsets, data cards, wireless modems and other WCDMA/HSPA devices. When developing a new design, engineers need to consider the important functional requirements of the design and consider changing the matching network discussed here to achieve the best trade-offs in output power, linearity, efficiency, and other RF parameters. Reviewing the load pull of each power amplifier will help determine the best output impedance match point that may not be 50Ω. The engineer must also consider the RF path and network selection for each part of the variation, reduce the antenna output variable, and do not exceed the expected operating temperature, frequency, and supply voltage to maintain all RF parameters at acceptable levels. Finally, it is important to control the reflection (return loss) of the power amplifier to avoid instability or oscillations in the circuit.
• AWT6221: WCDMA/HSPA HELP3 for dual mode PA in UMTS bands 2 and 5
• AWT6222: WCDMA/HSPA HELP3 for dual mode PA in UMTS bands 1 and 6
• AWT6224: WCDMA/HSPA HELP3 for dual mode PA in UMTS bands 1 and 8
• AWT6321: CDMA/EVDO HELP2 is suitable for dual mode PA in the cellular and PCS bands.