Low phase noise operation of microwave oscillator circuits

Abstract

In this paper, we describe a theoretical basis, leading to new results, on the general conditions to be fulfilled by oscillator circuits to achieve a very low phase noise. Three main conditions must be fulfilled by a transistor oscillator circuit to reach the minimum phase noise. The energy stored in the resonator must be maximum. Its transfer to the controlling voltage port of the transistor current source must be first maximized. A possible conversion noise at the transistor output port will be also minimized by maximizing the energy transferred to that port. The proposed method has been applied to an experimental oscillator set up with a PHEMT transistor. A state-of-the-art phase noise of -80 dBc/Hz at 100 Hz offset from carrier with a 1/f(3) slope has been measured at room temperature with a 9.2 GHz, oscillator. The application of these new results to free-running oscillator circuits with one-stage then multistage transistor amplifiers demonstrate clearly the validity of the design method. The efficiency of this design method and its ease of use represent a real breakthrough in the field of low noise transistor oscillator circuit design.

Phase Noise Spectral Limits in OFDM Systems

“…The standard model for the phase noise in free-running oscillators [16][17][18][19] is given below in terms of the slope of the phase noise spectrum in a Bode diagram and shown in Figure 2 Wiener This corresponds to a phase noise spectrum deriving from the sum of independent phase noise components, given by…”

“…In [5] the analysis is extended to a phase noise spectrum model as proposed in [15], with exponential decay, to derive a comparison of the achievable bit-rate for DMT and FMT in the presence of phase noise and multipath. However, a model more general than the classical Wiener process and closer to the measurements considers the phase noise as the superposition of several components which have different spectrum signatures [16][17][18][19]. With these phase noise characteristics, the error probability of single carrier DPSK systems has been obtained from the variance of each spectral component [20].…”

Feedforward Data-Aided Phase Noise Estimation from a DCT Basis Expansion

“…(i) Designing oscillators operating at low-phase noise reduces the need of accurate phase noise compensation algorithms. This, however, leads to expensive oscillators which are difficult to integrate on chip [6][7][8].…”