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Indian Journal of Engineering and Materials Sciences (IJEMS) >
IJEMS Vol.17 [2010] >
IJEMS Vol.17(1) [February 2010] >
| Title: | Design of low phase noise InGaP/GaAs HBT-based differential Colpitts VCOs for interference cancellation system |
| Authors: | Shrestha, Bhanu
Kim, Nam-Young |
| Keywords: | Differential VCO
InGaP/GaAs HBT VCO
MMIC VCO
Voltage controlled oscillator
Differential Colpitts VCO
Low phase noise VCO
Colpitts oscillator |
| Issue Date: | Feb-2010 |
| Publisher: | CSIR |
| Abstract: | This paper presents design, fabrication and
characterization of two differential Colpitts voltage controlled oscillator
(VCOs) - cross-coupled VCO (CC-VCO) and double cross-coupled VCO (DC-VCO) - in
InGaP/GaAs HBT technology. Their main parameters like the oscillation
frequency, output power and phase noise performance are measured and compared
with other recently published studies. In the cores of two VCOs, two switching
transistors are introduced to steer the core bias current to save power. An LC
tank with higher inductor quality factor (Q) is used to generate
oscillation frequency. The differential CC-VCO exhibited a superior phase noise
characteristics of-130.12 dBc/Hz at 1 MHz from the carrier frequency (1.566
GHz) when supplied with a control voltage of 0 volt. In the same way, the
differential DC-VCO achieved -134.58 dBc/Hz at 1 MHz from the carrier frequency
(1.630 GHz) with the same control voltage. Two pairs of on-chip base collector
(BC) diodes are used in the tank circuit to increase the VCO tuning range. It
is concluded that the faster switching action of InGaP/GaAs HBT transistors
exhibited the excellent phase noise characteristics. |
| Page(s): | 34-38 |
| ISSN: | 0975-1017 (Online); 0971-4588 (Print) |
| Source: | IJEMS Vol.17(1) [February 2010]
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