Because of the ever-increasing functionality required by cellular handsets, the industry is continuously pushing for higher integration. Integration in the RF front end has reached new levels due to highly integrated RF transceivers, particularly those implemented in CMOS. However, until now, a significant amount of board space within a cellular phone has been taken up with the RF power amplifier and associated external components including power control circuits, decoupling capacitors and input pad. Power amplifiers have historically been implemented in GaAs (gallium arsenide) or other esoteric process technologies, but never in standard process CMOS. Additionally, a number of companies have produced RF PA modules, which contain multiple die and many discretes, complicating their design and manufacturing process. Silicon Laboratories is the first company to design a truly monolithic PA integrating the high and low band PA functions as well as the complete power control circuits. This new PA is not only monolithic, but also the first GSM/GPRS PA manufactured in standard digital CMOS, overcoming many of the formidable technical challenges that have frustrated the industry for years. All past research on a CMOS GSM PA has been able to either generate the required power or operate at the high battery voltage required by cell phones. Before now, no one has ever been able to generate the high power and operate at the high battery voltage. The principal roadblock has been gate oxide breakdown. Traditional non-linear power amplifier architectures, such as the Class-E power amplifier, generate voltages in the region of 12.5V, significantly in excess of that which the CMOS gate oxide can tolerate. As a result, these traditional architectures rely on esoteric, and expensive, process technologies. Silicon Laboratories followed a circuit approach rather than a device physics approach, allowing innovation at the circuit level to create an architecture using standard process s technology. They discovered a method of distributing these high voltages generated during amplification among multiple devices. Using this new architecture, no single device is subjected to any voltage greater than that which the gate oxide can tolerate. This fundamental breakthrough allowed the creation of a GPRS Class 12, CMOS monolithic PA that reduces both board space and component count by more than 70% compared with previous solutions.The new device, known as the Si4300, uses a single die manufactured in TSMC's standard and well-proven 0.35-micron CMOS process, and it is the first GSM/GPRS PA solution to be implemented in standard CMOS. A functional block diagram is shown in Fig. 1. The device integrates all functions between the transceiver and the antenna switch module including power control circuitry, thermal and load mismatch protection, harmonic filtering, and input and output matching networks. All this is packed into a 25mm2, 18-pin Land Grid Array (LGA) package (3.9mm x 6.4mm x 1.3mm) and requires no external discretes.Despite the leap in miniaturization that the Si4300 represents, there is no performance compromise with respect to any of the critical characteristics of importance to cellular phone designers. In fact, 3GPP specifications are exceeded across the operating conditions for harmonic suppression, cross-band isolation, input-to-output isolation and other key parameters.To summarise, Silicon Laboratories' Si4300 provides customers with the smallest, most integrated PA system as well as ample margin to key specs and a system that is easy to design into new or existing platforms. With the industry's leading performance and highest level of integration, the PA allows customers to integrate GSM functionality with fewer RF engineering resources, allowing RF engineers to be deployed on value-added projects such as the integration of Bluetooth, WLAN or GPS.