Integrated processors for wireless base stations continue to proliferate. The newest entry is Freescale’s QorIQ Qonverge B4420, which is designed for 3G/4G microcells and metrocells that serve as many as 256 active users. The B4420 supports LTE and LTE-Advanced in addition to 3G protocols.

Small-cell base stations can upgrade wireless networks more cheaply than adding macrocells. Sometimes, they fill areas of poor coverage in the macrocell network; in other cases, they add capacity where it’s needed most. Cost cutting and compact design are vital, so small cells favor processors that integrate the functions of multiple chips. A single SoC can replace a separate communications processor, DSP, FPGA, and Ethernet switch.

The new Qonverge B4420 is an economy model of the B4860, Freescale’s most powerful base-station processor (see MPR 3/19/12, “Freescale’s Qonverge Goes Macro”). These chips are pin compatible and the first Freescale products to sample in 28nm HPM technology. (Samples are due in 3Q12, with production scheduled for 2H13.) They almost certainly use the same die, improving yields by recovering some off-spec chips that would otherwise be discarded.

Compared with the B4860, the B4420 has a little less of everything. Instead of four Power e6500 CPU cores (1.8GHz maximum), it has two cores (1.6GHz maximum); instead of six StarCore SC3900 DSP cores, it has two DSPs (1.2GHz maximum); instead of two 64-bit DDR3/3L-1866 memory controllers, it has one 64-bit DDR3/3L-1600 controller; instead of four 1.0/2.5Gbps Ethernet ports, it has three ports; and instead of eight CPRI 9.8Gbps RF interfaces, it has four. The B4420 also omits the B4860’s dual 10GbE ports and serial RapidIO (sRIO) interfaces but retains the four-lane PCI Express (Gen3) controller.

Freescale estimates the B4420 will consume about 15W TDP—roughly half as much power as the B4860. We estimate it will also cost about half as much: $200 in volume. The first customers are undisclosed, but likely candidates are Alcatel-Lucent and Fujitsu—existing B4860 customers who could apply their design work across macrocells and microcells.