This manuscript presents the design of a low phase noise, high figure of merit (FoM) single-ended octagonal ring oscillator (RO). The proposed RO employs the pulse injection (PI) technique for performance enhancement. The PI technique is used for suppression of phase noise and spurious harmonics. Besides, a novel voltage dependent phase shifter is employed. The proposed RO has an output signal with voltage controlled phase. Different output signal phases can be obtained employing different selected voltages to control the output signal phase. The proposed injection locked ring oscillator (ILRO) represents a suitable implementation for phase shift keying. The proposed ILRO has a measured oscillation frequency of 4.9 GHz with a fine tuning range of 500 MHz. It has a measured phase noise of 2126.17 dBc/Hz @ 1MHz offset while consuming only 4.8 mW of DC power. The proposed ILRO has a FoM of 2193.17 dBc/Hz. This RO has been designed and implemented in 0.18 mm CMOS technology.
The optimization of optical density in film-screen mammography is crucial in attaining good image quality. While a target range for film optical density of 1.4-1.8 has been recommended for centres participating in the National Health Service Breast Screening Programme (NHSBSP), past investigations have shown that combinations of mammography film and screen and processor conditions can have various optimum densities, some of which are outside this recommended range. The optimum optical density of the film/screen/processor conditions combination used at our institution (the Kodak MIN-RM/MIN-R combination designed for standard-cycle processing) was evaluated using a breast detail phantom study. It was found that the optimum optical density was 1.25 OD. We recommend that an individual institution determines the optimum optical density for the film-screen combination it uses and the processing conditions specific to it.
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