A 5mA 2.4GHz 2-point modulator with QVCO for Zigbee tranceiver in 0.18-μm CMOS

A low power 2.4GHz 2-point modulator with quadrature voltage control oscillator (QVCO) is demonstrated for Zigbee transceiver application using 1P6M 0.18-μm RF CMOS process. Special design techniques are proposed to achieve accurate frequency deviation Δf, in the presence of varactor mismatches and process variations. Measured error vector magnitude (EVM) of the transmitter is 6.5% even without auto calibration for the error in Δf and the spectrum meets 802.15.4 mask with margin. The implemented transmitter modulator covers 2405MHz to 2480MHz band with 16 channels each 5MHz wide as allocated by IEEE 801.15.4. The synthesizer also provides IQ output when operated in the receiver mode with a measured phase noise of -109dBc/Hz at 1MHz offset over the entire tuning range. The active die area is 1mm × 1mm. The chip operates over a wide range of supply voltage from 1.6V to 2.0V and temperature from -40°C to +85°C. The chip draws 5mA current from a +1.8V supply at +25°C.