Digital pre-distortion (DPD) has emerged as one of the best ways to improve the linearity and efficiency of power amplifiers (PAs) used in wireless basestations. This system monitors the output of the PA, digitizes it, and sends it back to a DSP or FPGA, where algorithms correct for any distortion in the amplifier. This keeps the power and efficiency high and reduces overall distortion over a wider bandwidth.

But while DPD is a great solution, it is tricky to implement. Now, Analog Devices and Altera have joined together to give designers a quicker and easier way to incorporate PAs for broadband multi-carrier basestations that are becoming the norm as carriers move to higher-bandwidth techniques like HSPA+ and Long-Term Evolution (LTE).

The Analog Devices MS-DPD (mixed-signal, digital pre-distortion) high-performance development platform targets wireless infrastructure equipment designers who need to quickly evaluate systems using DPD techniques in multi-carrier cellular basestations. It integrates a complete high-performance RF and mixed-signal transmit chain from ADI with any FPGA development kit with a high-speed mezzanine card (HSMC) connector from programmable-logic vendor Altera (see the figure).

The complete multi-carrier development platform reduces the time spent on component selection, interoperability issues, and board layout while freeing design resources to optimize the DPD algorithms required by multi-carrier GSM and multi-standard software-defined radio (SDR) applications. FPGAs enable designers to quickly reprogram DPD algorithms during product development to correct for nonlinearities in the radio’s transmit path while improving the power efficiency of the entire radio. FPGAs also provide the flexibility to optimize the solution that competing fixed-function ASICs cannot.

This development package allows engineers to lower development overhead and time-to-market by offering the complete circuitry and components needed to make a complete basestation radio. It lets engineers focus on differentiation in their DPD implementations. The in-field-programmability feature of Altera FPGAs significantly lowers the risk of introducing new technologies such as DPD, while also offering scalability to further enhance flexibility.

The MS-DPD development board includes 12 Analog Devices RF and mixed-signal components, including the AD9122 1.2-Gsample/s digital-to-analog converter (DAC) and the ADL5375 quadrature modulation in addition to amplifiers, mixers, clock ICs, power-management ICs, and phase-locked loop (PLL) circuits. The reverse observation path includes the AD9230 12-bit, 250-Msample/s analog-to-digital converter (ADC) to maximize the bandwidth available for DPD.

The MS-DPD development boards are available today to qualified customers from ADI for $3995 each.

Altera

Analog Devices