The design experience described here is a tunable monolithic frequency source for millimeter wave applications that can generate frequencies from 8 GHz to 18 GHz.  This design experience was on Jazz SiGe120 (SBC18) Bi-CMOS process.  It consists of a tunable VCO including an optimized resonator and a x2 frequency multiplier.  Voltage Controlled Oscillator (VCO) can be designed over a wide frequency band from 4 GHz to 9 GHz. VCO is in a differential configuration to reduce substrate and source noise. The low phase noise of -110 dBc/Hz @ 1 MHz offset is achieved through a careful design of high Q tank circuit and bias circuits. VCO has capability of coarse tuning and fine tuning using tank circuits. The coarse tuning can be performed over wide frequency bandwidth of 3 GHz. Fine Tuning range could be 1- 2% with a sensitivity of 10-100 MHz/V. The two times frequency multiplier following VCO is a differential multiplier with a differential output impedance of 100 ohms. The MMIC can be easily configured to increase the frequency range coverage.  The frequency of 4-9 GHz provides locking possibility through PLL and use of external resonator to further improve noise performance.

• Center frequency: 8 GHz to 18 GHz in different selective frequency bands
• Fine tuning range: 1 – 2%
• Phase noise: -110 dBc/Hz @ 1 MHz offset, -95 dBc/Hz @ 100 KHz offset
• Tuning sensitivity :  50 MHz/V to 100 MHz/V
• Low current consumption: 20-30 mA
• Temperature compensation -40 to 125 degree C

Block Diagram