Yukinori Sakuta

A study on configuration of oscillator circuit for improving phase noise

The advancement of the communication technology in recent years demands the technology of the high frequency and low phase noise of oscillator required for mobile telecommunications. In general, there are two important things for improving the phase noise characteristics of the oscillator. One is a design that the phase noise in the amplifier is suppressed to low. The other is a design having loaded Q as greatly as possible. In this paper we discuss a configuration of oscillator circuit to obtain an extremely low phase noise and an oscillator operating at a non-reactive frequency of SAW resonator.

Precision test fixture for measuring equivalent circuit parameters of GHz surface-mounted quarts crystal units

We developed a coaxial-type fixture for precisely measurement of the impedance characteristics of small surface-mounted quartz crystal units. This fixture is applicable to the one-port S-parameter reflection method proposed in IEC60444-5, and measures the frequency impedance characteristics of a device under test (DUT) from its reflection coefficients. This measurement fixture uses a 65 GHz coaxial connector and calibrators with a 1.85 mm inside diameter. Using a “zero-length” coaxial center pin method, this fixture can be applied to up to 2 GHz devices without the need for electrical length compensation.

A basic examination of estimating the magnitude of TSUNAMI by T-wave

Paying attention to the sound of breaking sea bottom depending on the magnitude of TSUNAMI, we examined the acquisition of a sea sound wave at Japan waters. We considered the traveling route of the sea sound wave radiated from the hypocenter of the Tohoku-Pacific Ocean Earthquake, and estimated the propagation loss, which has a characteristic that the diffusion loss depending on distance is dominant. Thus, the sound pressure level of the hypocenter was presumed being at least 252 dB. (0 dB = 1u Pa). A sea sound wave radiation from the earthquake with the tsunami in Japanese waters is expected to attenuate the receiving about 55 dB at an area along the shore.

A new method to increase loaded Q of extremely low phase noise SAW oscillator

We have previously proposed a circuit configuration of SAW oscillator for extremely low phase noise, the name of which is Fr oscillator. The Fr oscillator has been able to realize extremely low phase noise floor level in calculation; however, the loaded Q is lower than Colpitts type oscillator. Then we propose new method to increase loaded Q. Using this method, we show several characteristics of the loaded Q. Based on the results, we estimate SSB phase noise of the Fr oscillator. As a result, the phase noise level is improved about 15 dB in the neighborhood of carrier frequency if the input/output impedance of the frequency selective circuit is reduced. Furthermore, we make a couple of Fr oscillators using crystal resonator. The measured phase noise characteristics are corresponding to the calculated value well. It is clear that this method is effective for improving phase noise of near the carrier frequency.

Precise Frequency Comparison via Broadcasting Satellite.

A method of highly precise comparison for frequency received via a broadcasting satellite (BS) has already been proposed. The problem with that method, however, is that the orbit data required to make corrections are unavailable to general users.This paper proposes a method of highly precise frequency comparison that can eliminate the effect of doppler shifts from color sub-carrier frequencies received via the BS without orbit data. This method is a kind of data processing using a Fourier series to express the doppler shifts versus time characteristics. With this proposed method, 1) The effect of doppler shifts can be suppressed to less than approximately 30 (dB), 2) Deviations in frequency can be detected with a precision on the order of 10-11, This paper also discusses the nature of color sub-carriers received via the BS in comparison with color sub-carriers received via the VHF band of television system.