Figure 5: Linksys WRT320N
For its first Linksys dual-band single-radio draft 11n router, Cisco stuck with Broadcom, using its BCM4717 Intensi-fi XLR 802.11n (2.4/5 GHz) Router System-on-Chip to really drive down cost (Figure 6).
Figure 6: WRT320N inside
It's a three-antenna design, with once again a heatsink on the gigabit switch chip. So I'll stick with the same guess as on the WRT610N, a Broadcom BCM5397 5 port gigabit switch. Figure 7 shows the SiGe 2547A RF front ends that live under the RF shield.
Figure 7: WRT320N RF front end
Figure 8 shows the 2547A's block diagram, detailing its power amplifiers, filtering, power detector, Diversity switch, diplexers and associated matching.