Photonic‐assisted wideband phase noise measurement of microwave signal sources

Abstract

A photonic-assisted scheme for the phase noise measurement of microwave signal sources is proposed based on the optical delay-line method. In the proposed scheme, all the microwave signal processing is implemented in the optical domain, and the electrical devices that would limit the operation bandwidth and measurement sensitivity are avoided, leading to a large operation bandwidth and a high sensitivity. The feasibility of the proved phase noise measurement system is experimentally verified. A large operation bandwidth of 5-40 GHz is achieved, and a phase noise floor as low as −140 dBc/Hz at 10 kHz offset is obtained.

Wideband microwave phase noise measurement based on photonic-assisted I/Q mixing and digital phase demodulation

“…Photonic-delay-line-based phase noise measurement, which acquires the phase noise by mixing the signal under test (SUT) with its optically delayed replica, attracts great attentions thanks to its high phase noise measurement sensitivity [4][5][6][7]. To measure the phase noise of signals in a large frequency range, the bandwidth limitation of electrical phase shifters and frequency mixers should be overcome, which can be solved by implementing microwave phase shifting and frequency mixing in the optical domain [8][9][10][11]. However, a feedback loop is required in these systems to ensure that the SUT and its delayed copy are quadrature to each other before sent to a frequency mixer, which is usually implemented by dynamically controlling an adjustable electrical or microwave photonic phase shifter incorporated in the feedback loop.…”

Self-calibrating and high-sensitivity microwave phase noise analyzer applying an optical frequency comb generator and an optical-hybrid-based I/Q detector

“…Considering the variation of φ 1 t due to the phase noise of a typical LD would exceed 2π in a short observation time [13], according to Eqs. (4) and (5), the maximum value of v i t is proportional to R i , and thus R 1 ∕R i can be figured out by…”

“…In radar, communication, and navigation systems, high-stability microwave signals are highly demanded [2,3], and a high-sensitivity phase noise analyzer (PNA) is indispensable for measuring microwave signals having a low phase noise. Among the various methods for establishing a PNA, the photonic-delay-line-based frequency discriminator method has attracted a lot of attention because it can achieve a high sensitivity and a large measurement frequency range with the help of microwave photonic technologies [4][5][6][7]. In this method, to achieve a high phase noise measurement sensitivity, a large time delay is required [8], which, however, will reduce the reliable offset frequency range for phase noise measurement.…”

“…The obtained four electrical signals in Eqs. (4) and (5) are digitized by a four-channel analog-to-digital converter (ADC), and the obtained digital signals are processed to acquire the phase noise of the SUT. Based on Eqs.…”

“…First, thanks to the use of balanced photodetection, the obtained signals in Eqs. (4) and (5) are free from the direct component (dc) interference, which is undesirable in zero-intermediate-frequency signal processing [7]. Besides, in obtaining Eq.…”