Abstract
A methodology for the harmonic-balance analysis and design of rotary-traveling wave oscillator is presented. Two different implementations are compared. The first one is the standard configuration based on a distributed transmission lines. The second one is a new configuration based on a differential nonlinear transmission line (NLTL), which enables the generation of square waveforms with reduced number of stages, while still maintaining the capability to produce multiphase signals. The possible coexistence of oscillation modes is investigated with a detailed bifurcation analysis versus practical parameters such as the device bias voltage. The phase-noise spectrum is predicted from the variance of the common phase deviation. The parameters that determine this variance are identified with the conversion-matrix approach. The two prototypes, based on a distributed transmission line and a differential NLTL, have been manufactured and characterized experimentally, obtaining very good agreement between simulations and measurements.
Highlights
A methodology for the harmonic-balance analysis and design of rotary-traveling wave oscillator (RTWO) is presented
With the aim to reduce the number of stages required to achieve a square waveform a new configuration based on the use of a differential nonlinear transmission line (NLTL) is proposed
A new RTWO configuration based on the use of nonlinear transmission lines (NLTL) has been presented
Summary
EMERGING communication standards demand signal sources with multiple phases. In a conventional approach the multiphase oscillation signals are generated through the coupling of LC-tank oscillators [1]-[8]. The basic RTWO architecture is a Möbius-ring-like differential transmission line with gain stages periodically distributed along the path. The distributed nature of this oscillator alleviates the effects of the transistor parasitics [9] and enables lower phase-noise spectral density Another significant advantage is that accurate differential quadrature outputs needed for I/Q modulation and demodulation can be obtained at the fundamental oscillation frequency. In the case of periodic regimes, a small-signal current source at a frequency Ω incommensurable with the fundamental frequency ωo of the periodic regime is introduced into the circuit, calculating the closed-loop transfer function Z(Ω) = V(Ω)/I(Ω) [18,19] with the conversion-matrix approach [20].
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