1. Overview The SE2425U power amplifier is a miniature power amplifier optimized for standard Bluetooth and enhanced data rate (EDR) applications. In standard GFSK mode, the SE2425U delivers +25 dBm output power; in enhanced 8DPSK mode, it delivers +19.5 dBm. In both modes, the SE2425U also provides an industry-leading +20 dBm antenna, ensuring stable and reliable transmission over longer distances. The SE2425U achieves Bluetooth wireless connectivity with a range of up to 100 m and bandwidths up to 3 Mbit/s. The SE2425U is suitable for Bluetooth phones, PDAs, wireless headsets, laptops, and cordless phones. It optimizes EDR performance and supports EDR over longer distances. Based on a high-efficiency silicon-germanium structure, the SE2425U ensures a current consumption as low as 120 mA with a single 3.3 V supply and an output power of +20 dBm. In addition, the SE2425U features low current consumption and a power-saving mode, achieving support for both Class 1 and Class 2 operation for the first time in battery-powered mobile devices; the SE2425U has very low quiescent current, supporting both Class 1 and Class 2 operation in the same design without affecting battery life. In the Class 2 output power stage, the current consumption is only 29 mA. 2. Key Technical Specifications 2.1 SE2425U Related Parameters The maximum rated values ​​of the SE2425U related parameters are listed in Table 1. [img=330,161]http://cms.cn50hz.com/files/RemoteFiles/20090204/579404001.jpg[/img] 2.2 Electrical Characteristics Under the conditions of VCC0=VCC1=VCC2=VCC3=3.3 V, TC=25℃, and f=2.45GHz, the DC characteristics of the SE2425U are listed in Table 2. With VEN=VCC0=VCC1=VCC2=VCC3=3.3 V, VMODE at low level, PEN=-6dBm, TC=25℃, and f=2.45GHz, the AC characteristics of the SE2425U are listed in Table 3. 3. Internal Structure The SE2425U is housed in a small 16-pin QFN package (3 min × 3 mm × 0.5 mm). The SE2425U is the first fully integrated power amplifier, and its internal structure is shown in Figure 2. The SE2425U also includes an integrated CMOS startup interface, combined with input matching, power supply decoupling, inter-stage matching, and an "easy-match" output. This output matching integrates a high-Q inductor to reduce component count and bill of materials. The device requires only two external capacitors, thus offering flexibility to collaborate with multiple switch and filter suppliers at a high cost and to address wiring constraints associated with different applications. 4. Characteristic Curves The SE2425U is a power amplifier specifically designed for both Bluetooth EDR and basic rate. The SE2425U features a digital mode switch that allows for switching amplifier bias between high-power and low-power modes. This mode switch is fabricated using CMOS technology, enabling dynamic mode switching based on the data packet package; alternatively, designers can provide a hard-connected bias scheme to meet output power and linearity requirements. In high mode, the quiescent current is approximately 81 mA, while the SE2425U delivers 20 dBm of EDR output power while still meeting spectrum requirements. In low mode, the SE2425U boasts an ultra-low quiescent current of only 29 mA and an EDR output power of 25 dBm. In both modes, the basic Bluetooth output power remains around 25 dBm, with a 5 dB margin to account for significant losses in the subsequent PA, while still meeting all Class 1 requirements. Figure 3 shows the characteristic curve of the SE2425U in low mode under the detection conditions of VEN=VCC0=VCC1=VCC2=VCC3=3.3 V, VMODE low, TC=25℃, and f=2.45 GHz. Under the detection conditions of VEN=VCC0=VCC1=VCC2=VCC3=3.3 V, VMODE at high level, TC=25℃, and f=2.45 GHz, the characteristic curve of SE2425U in high mode is shown in Figure 4. [img=598,433]http://cms.cn50hz.com/files/RemoteFiles/20090204/579404003.jpg[/img] 5 Portable Product Application Design In addition to improving EDR performance and reducing current consumption, the power amplifier SE2425U can also reduce the bill of materials and shrink the overall size of the Class 1 Bluetooth solution. This simple digital bias solution ensures low power consumption for the Class 2 power stage while maintaining efficient enhanced rate operation at high output power. Figure 5a shows the legacy structure used in a conventional design to achieve both Class 1 and Class 2 operation using an older base rate power amplifier. This solution requires an additional switch, allowing the transmitter to completely bypass the power amplifier when Type 2 operation is needed. Figure 5b shows how to implement this solution using the SE2425U without requiring the bypass switch component. In the Type 2 output power stage, the SE2425U will operate in the quiescent range, still providing gain to allow the Bluetooth transmitter to transmit at lower output power, thus reducing transceiver current consumption.