Ferre-Pikal Eva S, Savage Frederick H
Electr. & Comput. Eng., Univ. of Wyoming, Laramie, WY, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2008 Aug;55(8):1698-704. doi: 10.1109/TUFFC.2008.855.
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.
在本文中，我们描述了一种预测微波异质结双极晶体管（HBT）放大器中1/f基带电流噪声上变频所导致的1/f相位调制（PM）和1/f幅度调制（AM）噪声的技术。我们获得了该放大器的精确模型，并根据直流偏置、晶体管参数和电路元件得出了电压增益的表达式。然后，通过将PM和AM噪声的定义应用于放大器的增益表达式，得出了理论上1/f PM和AM噪声对1/f基带电流噪声的灵敏度。在500 MHz和1 GHz下对PM和AM灵敏度的测量结果与理论预测值高度吻合，验证了该技术的有效性。此方法可用于优化放大器设计，以降低PM和AM噪声。我们表明，通过调整输入耦合电容的值，放大器的PM噪声可降低9 dB。
