Title :
Up-converted 1/f PM and AM noise in linear HBT amplifiers
Author :
Ferre-Pikal, Eva S. ; Savage, Frederick H.
Author_Institution :
Electr. & Comput. Eng., Univ. of Wyoming, Laramie, WY
fDate :
8/1/2008 12:00:00 AM
Abstract :
In this paper we describe a technique to predict the 1/f phase modulation (PM) and 1/f amplitude modulation (AM) noise due to up-conversion of 1/f baseband current noise in microwave heterojunction bipolar transistor (HBT) amplifiers. We obtain an accurate model for the amplifier and find the expression for voltage gain in terms of DC bias, transistor parameters, and circuit components. Theoretical 1/f PM and AM noise sensitivities to 1/f baseband current noise are then found by applying the definitions of PM and AM noise to the gain expression of the amplifier. Measurements of PM and AM sensitivities at 500 MHz and 1 GHz were in good agreement with the values predicted by theory, verifying the validity of this technique. This method can be used to optimize amplifier design for low PM and AM noise. We show that the amplifier PM noise can be reduced by 9 dB by adjusting the value of the input coupling capacitor.
Keywords :
1/f noise; UHF amplifiers; amplitude modulation; bipolar transistor circuits; circuit noise; heterojunction bipolar transistors; microwave amplifiers; phase modulation; AM; PM; frequency 1 GHz; frequency 500 MHz; input coupling capacitor; linear HBT amplifiers; microwave heterojunction bipolar transistor amplifiers; upconverted 1/f amplitude modulation noise; upconverted 1/f phase modulation noise; Amplitude modulation; Baseband; Circuit noise; Heterojunction bipolar transistors; Microwave amplifiers; Microwave theory and techniques; Noise level; Phase modulation; Phase noise; Voltage; Artifacts; Computer-Aided Design; Electronics; Equipment Design; Equipment Failure Analysis; Microwaves; Oscillometry; Sensitivity and Specificity; Transistors, Electronic;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
DOI :
10.1109/TUFFC.2008.855