High Power HBT-MMIC Oscillator for 2.4 GHz Wireless Application

Using HBT foundry parameters, a 1 Watt buffered Colpitts oscillator will be designed with high efficiency, low phase noise, low harmonic distortion, low voltage, and small chip size. The intended application is for the transceiver in a wireless LAN. The proposed circuit is a 10 mW Colpitts common collector oscillator followed by a two stage buffer amplifier, which isolates the resonator from load variations. The oscillator will use HBTs with a low 1/f corner frequency, and it can be varactor tuned over a narrow frequency range. This design will be completed using Hewlett Packard Microwave Design System (MDS) and/or Hewlett Packard Libra at the Santa Clara University Computer Design Center. The expected phase noise is -100 dBc at 100 KHz from the 2.4 GHz carrier and the efficiency goal is greater than 50%. The key to the success of this design is obtaining an accurate modified Gummel-Poon nonlinear model with correct 1/f noise parameters. Dr. Robert Anholt has provided these parameters for the WPAFB foundry and the TRW foundry. Other foundries which will be considered include the Rockwell Science Center and Texas Instruments. Phase I includes the MMIC design of the oscillator, the buffered amplifier, and the total integrated buffered oscillator. Phase II will be directed toward the fabrication and measurement of the MMIC chips, which can be tested in the Santa Clara University Microwave Measurement Laboratory. The other key to this program is to understand the market requirements, especially the price which the consumer is willing to pay for this wireless application. The performance/price tradeoffs are going to be crucial to the success of this program.