Detailed Description

Wideband signals in today’s telecommunications systems have high peak-to-average ratios and stringent spectral regrowth specifications. These specifications place high linearity demands on power amplifiers. Linearity may be achieved by backing off output power at the price of reducing efficiency. However, this increases the component and operating costs of the power amplifier. Better linearity may be achieved through the use of digital predistortion and other linearization techniques, but many of these are time consuming and costly to implement. Wireless service providers are deploying networks with wider coverage, greater subscriber density, and higher data rates. These networks require more efficient power amplifiers. Additionally, the emergence of distributed architectures and active antenna systems is driving the need for smaller and more efficient power amplifier implementations. Further, there continues to be a strong push toward reducing the total capital and operating costs of base stations.

With the SC1905, the complex signal processing is done in the RF domain. This results in a simple system-on-chip that offers wide signal bandwidth, broad frequency of operation, and very low power consumption. It is an elegant solution that reduces development costs and speeds time to market. Applicable across a broad range of signals—including 2G, 3G, 4G, 5G wireless, and other modulation types—the powerful analog signal-processing engine is capable of linearizing the most efficient power amplifier topologies. The SC1905 is a true RFin and RFout solution, supporting modular power amplifier designs that are independent of the baseband and transceiver subsystems. The SC1905 delivers the required efficiency and performance demanded by today’s wireless systems.

The SC1905 contains a microprocessor that is executing firmware. The system software referred to henceforth as the "host", communicates with the firmware through a handshaking protocol called the message protocol. The host configures the SC1905 by writing to various parameters stored in an EEPROM contained within the SC1905, or by issuing commands to the firmware through the message protocol. All this communication is done through a 4-wire Serial Peripheral Interface (SPI).

Detailed information on the message protocol, accessing EEPROM, etc. is contained in the SC1905 SPI Programming Guide. Figure 1 shows the timing relationships between the SPI signals. Refer to Table 1.

Table 1. Serial Interface Timing Requirements