INJECTION-LOCKED OSCILLATOR CHAIN - A POSSIBLE SOLUTION TO MILLIMETER-WAVE MMIC SYNTHESIZERS

An injection-locked oscillator (ILO) monolithic-microwave integrated-c ircuit (MMIC) chain-a cascade of low- and high-frequency-hand ILO's-is proposed for simple and cost-effective millimeter-wave local oscillat ors and synthesizers. Primary 5-, 20-, and 50-GMz-band ILO MMIC's are designed and fabricated as an ILO-chain chip set, Improvements made to the active combiner/dividers (A-C/D's), the heart of the MMIC, in the external Feedback path for an amplifier to suppress spurs at the outp ut part of 5- and 20-GHz-band ILO's, and enhance the loop gain and lay out flexibility at millimeter-wave frequencies. Fabricated 5- and 20-G Hz-band ILO MMIC's are chain-connected to confirm the design technique s, The ILO chain pro,ides a 20-GHz-band output signal for an injection signal of 571 MHz, as well as a very low level of spurs of less than -45 dBc around the output signal. The measured results show that the p roposed ILO chain is extremely suitable for developing full millimeter -wave MMIC frequency synthesizers.