ZigBee(IEEE 802.15.4)system requires low power, low cost and small size transceiver. So we need highly efficient CMOS driver amplifier and small size PCB Balun and antenna.
Amplifier is a 2-stage one(Class AB+Class C) with 3.3 dBm output power, 34% PAE,3dB step power control.
Balun is one port shorted reduced λ/4 coupled line with 0.2dB amplitude error, 1˚ phase error, 80 MHz bandwidth.
Antenna is 2.8*1.5[cm*cm] sized inverted-F patch one with 230 MHz bandwidth,3 dBi gain, omni-directional pattern,2nd harmonic rejection.