A 2.7-V 170-MHz LC voltage-controlled oscillator for an IF wireless transceiver

An inductor-capacitor (LC) voltage-controlled oscillator (VCO) circuit that has been successfully implemented in a commercial intermediate-frequency ( IF) transceiver for the code-division multiple access (CDMA) mobile phone i s described. The circuit incorporates automatic amplitude control (AAC) to set the oscillation amplitude and a modified differential output stage to m inimize even-order harmonic distortions. The phase noise level, which is me asured at the single-ended buffer output, is -109.3 dBc/Hz at a 100-kHz off set front the carrier frequency of 170.76-MHz. The circuit has been fabrica ted in a 0.5-mum 15-gHz f(T) Si BiCMOS process, is designed to operate over a supply voltage range of 2.7 similar to3.6 V, and draws a current of 4.0- mA from the supply.