No abstract

The S band limits from 2 to 4 GHz, is part of the electromagnetic spectrum’s microwave band. It is used by radars, satellites and some communications. This paper is concerned with the theory and design of 3 GHz feedback type and negative resistance oscillators by using Aiglent ADS software simulator with GaAs ED02AH 0.2-μm technology, and comparison of their results. A lumped element resonator has used in the design of feedback type oscillator and a negative resistance oscillator has utilized a microstrip resonator. The negative resistance oscillator operates at 3.072 GHz with phase noise levels at -99.49 dBc/Hz and -119.6 dBc/Hz at 100KHz and 1 MHz offset frequencies respectively. The phase noise levels of feedback type oscillator are -83.30 dBc/Hz and -103.3 dBc/Hz at 100KHz and 1 MHz offset at oscillation frequency of 3 GHz. Furthermore, we compared the output power of these oscillators and negative resistance oscillator showed 7.124 dBm, and feedback type oscillator presented -10.707dBm.

This paper describes the 0.35 um SiGe BiCMOS Voltage Controlled Oscillators (VCOs). One is Cross-coupled VCO, and the other one is Colpitts VCO. Both of them are designed with the same method. For achieving lower noise, the differential structure was used at this design. The center frequency for Cross-coupled VCO and Colpitts VCO is 5GHz. The tuning range of Cross-coupled VCO and Colpitts VCO is 1750 MHz and 230 MHz, respectively. The phase noise and the figure of merit (the FOM) for Cross-coupled VCO, are -155.5 dBc/Hz and -224.7dBc/Hz @1MHz offset frequency at an oscillation frequency of 5GHz, respectively. The phase noise and the figure of merit value of Colpitts VCO is -134.1 dBc/Hz and -200.3 dBc/Hz at the 1MHz offset from the center frequency of 5GHz. For The DC current of Cross-coupled and Colpitts VCO is 2 mA and 4 mA , respectively. Considering a 3.0 V supply Cross-coupled voltage (VCC) for both VCOs. The output power of Cross-coupled VCO is -3.94 dBm and the Colpitts VCO achieves an output power of 5.428 dBm. Agilent ADS software is used throughout this work