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This paper proposes the use of N-push operation for combining the functions of the VCO and divider in the mm-wave frequency range. If employed in a PLL, the combined VCO/divider (C-VCO/D) would potentially provide wider tuning range than traditional mm-wave PLLs employing injection locked frequency dividers, thus exploiting the full range available in the 60 GHz band (57 GHz-64 GHz). The behavior of triple push oscillators based on injection locking theory is analyzed to study their various oscillation modes, their stability and the effect of mismatch on the oscillator performance. Design guidelines are provided for boosting the third harmonic power at a given power budget. Using 130 nm IBM CMOS technology, multiple versions of the triple push oscillator are implemented and characterized. A 55 GHz-65 GHz tuning range is obtained using a 206 pH tank inductance and requires Icore = 20 mA, and Ibuffer = 15 mA from a 1.4 V supply. For a tank inductance of 140 pH, a 63.2 GHz-72.4 GHz tuning range is obtained using Icore = 17 mA, and Ibuffer = 18 mA with a phase noise of -91 dBc/Hz at 10 MHz from the 63.2 GHz carrier and -95 dBc/Hz at 10 MHz from the 72.4 GHz carrier.
Date of Publication: Aug. 2010