Jennic

Jennic offers chips that combine microcontroller, IEEE802.15.4 ( 2.4GHz ) radio transceiver, and ADC. The chips support ZigBee, ZigBee Pro, and JenNet protocols, including meshed networks. Some Jennic chips include a "Time of Flight ranging engine".
 * Jennic web site

Product examples

 * Jennic Zigbee modules at Digikey
 * Jennic radio transciever + microcontroller ICs at Digikey (as used in the above modules)