Avramov Ivan D
Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria.
IEEE Trans Ultrason Ferroelectr Freq Control. 2006 Apr;53(4):707-15.
Nonlinear sustaining amplifier operation has been investigated and applied to high-power negative resistance oscillators (NRO), using single-port surface transverse wave (STW) resonators, and single-transistor sustaining amplifiers for feedback-loop STW oscillators (FLSO) stabilized with two-port STW devices. In all cases, self-limiting, silicon (Si)-bipolar sustaining amplifiers that operate in the highly nonlinear AB-, B-, or C-class modes are implemented. Phase-noise reduction is based on the assumption that a sustaining amplifier, operating in one of these modes, uses current limiting and remains cut off over a significant portion of the wave period. Therefore, it does not generate 1/f noise over the cut-off portion of the radio frequency (RF) cycle, and this reduces the close-in oscillator phase noise significantly. The proposed method has been found to provide phase-noise levels in the -111 to -119 dBc/Hz range at 1 KHz carrier offset in 915 MHz C-class power NRO and FLSO generating up to 23 dBm of RF-power at RF versus dc (RF/dc) efficiencies exceeding 40%. C-class amplifier design techniques are used for adequate matching and high RF/dc efficiency.
非线性维持放大器的工作已得到研究，并应用于高功率负阻振荡器（NRO），该振荡器使用单端口表面横波（STW）谐振器以及用于由双端口STW器件稳定的反馈回路STW振荡器（FLSO）的单晶体管维持放大器。在所有情况下，均采用工作在高度非线性AB类、B类或C类模式下的自限性硅（Si）双极维持放大器。相位噪声降低基于这样的假设：在这些模式之一下工作的维持放大器采用电流限制，并在大部分波周期内保持截止状态。因此，它在射频（RF）周期的截止部分不会产生1/f噪声，这显著降低了振荡器的近载频相位噪声。已发现，所提出的方法在915 MHz C类功率NRO和FLSO中，在1 kHz载波偏移处可提供-111至-119 dBc/Hz范围内的相位噪声水平，这些振荡器在射频与直流（RF/dc）效率超过40%时可产生高达23 dBm的射频功率。C类放大器设计技术用于实现适当匹配和高RF/dc效率。
