Abstract:
A broadband high frequency signal generator is disclosed having a low and a high frequency swept signal source connected to a YIG tuned frequency multiplier. One end of an output coupling loop for the YIG is connected to ground through a PIN diode, and the low frequency signal source is connected to the junction of the output coupling loop and the PIN diode. When the PIN diode is caused to conduct, signals from the high frequency source are passed through the YIG tuned multiplier to an output in the conventional manner. When the PIN diode is not conducting, signals from the low frequency source are passed to the output through the output coupling loop.
Abstract:
A method as described for setting the frequency of an RF source containing an oscillator having coarse and fine frequency controlling elements for generating RF signals for testing the RF response of devices by sweeping the RF signal source through a band of frequencies and detecting and analysing the signal transmitted by the device under test. A coarse comb signal based on harmonics of a first signal NMHz, and a fine comb signal based on harmonics of a second signal nMHz (N being much greater than n), are generated and the coarse and fine frequency controlling elements are calibrated. The oscillators are then swept through the frequency to which a marker relates and just beyond to detect the presence of the leading and trailing edges of the marker and the fine tuning control signal values corresponding to the edges are noted, a value for the frequency controlling signal corresponding to the mid-position of the marker is computed from the arithmetic mean of the leading and trailing edge values, and thus computed value used to calibrate the oscillator subsequently. Apparatus for performing the method is also described.
Abstract:
An RF source for generating RF signals by which components can be tested, which comprises a master oscillator (26), coarse and fine tuning controls (110, 112) and circuit means (Figure 6 and (34) Figure 5) for generating two sets of harmonically related markers for calibration, a low resolution set for coarse calibration and a higher resolution set (separated by smaller frequency intervals) for more accurate calibration, and signal generating means (20, 28) for producing control signals for operating the coarse and fine tuning controls, the values of the control signals being determined by reference to the harmonically related markers and the displacement of the desired frequency at which the master oscillator is to oscillate from the frequency of at least the nearest marker. A method of setting up such an RF source to oscillate at a particular frequency F is described using the two sets of markers to calibrate the signal generator.
Abstract:
Apparatus (11 or 41) for allowing low noise and fast frequency switching of a ferri-resonant oscillator, such as YIG, that uses a coil (13, 42) to control output signal frequency by current level. The apparatus positions an active filter (27) in parallel with the oscillator coil (13, 42), which can be set to one of two impedance levels. A low impedance level provides low pass filtering of the current to the oscillator coil for low noise operation. A second high impedance level allows fast settling of transients during frequency changes. Once current levels have stabilized, the active filter (27) can then be switched to low impedance mode without creating a significant transient. This facilitates fast frequency switching.
Abstract:
A tuned oscillator comprises an active element such as an FET (1) for oscillation and an YIG thin film ferrimagnetic resonator (2) connected to the FET (1) as part of a feedback circuit for the FET (1). The YIG thin film resonator (2) includes an YIG disc (2a) and has a bias magnetic field (H) applied perpendicular to a surface of the YIG disc (2a) to set the resonant frequency. The magnetic field (H) is generated both by a permanent magnet (4c) for providing a fixed component of the field and also by a coil (4b) for providing a variable component of the field. The resonant frequency is stabilised by a PLL circuit (5) connected to an output of the oscillator and with a feedback connection to the coil (4b). Since the YIG thin film tuned oscillator has a high Q value, high quality communication signal processing can be achieved. The YIG tuned oscillator may be used as a local oscillator for a transceiver.
Abstract:
A dual-resonator YIG oscillator with a main YIG resonator and a stabilizing YIG resonator both suspended in a common magnetic field. The main YIG resonator takes on the high-Q factor aspects of the oscillator, while the stabilizing YIG resonator helps stabilize the operation of the main YIG resonator, and also allows the main YIG resonator operate at higher magnetic field strengths, achieving higher frequency operation. The stabilizing YIG resonator also enables the oscillator's active device to operate in a more linear, lower phase noise, regime. As compared to conventional YIG oscillators, the disclosed dual resonator YIG oscillator provides significant performance improvements, such as higher frequency operation, lower power consumption, higher tuning speed, and lower phase noise.
Abstract:
A phase-lock loop for a swept synthesized source in which hysteresis, tuning nonlinearity, and drift over time and temperature of an oscillator incorporated into the swept synthesized source are compensated. The tuning current to the oscillator is initialized to zero to eliminate hysteresis effects. Then, the pretune current is set to produce the minimum operating frequency of the oscillator. Next, the main phase-lock loop is closed, and a low-frequency synthesizer is swept to in turn sweep the oscillator over a selected frequency span. If the selected frequency span extends over other frequency bands, the oscillator is swept to the maximum frequency of the present band and held at this frequency by a track and hold circuit. The main phase-lock loop is opened, the low-frequency synthesizer is re-initialized, the main phase-lock loop is again closed, and the low-frequency synthesizer is swept again. Each frequency band is crossed in a similar manner until the selected frequency span is swept. In order to improve phase-noise and transient response performance of the low-frequency synthesizer, a phase-lock loop speed-up and stability enhancement circuit comprising a zener diode connected across a passive lag-lead network is incorporated. Pretune calibration for the swept synthesized source is also provided.
Abstract:
A tuned oscillator utilizing a thin film ferromagnetic resonator is disclosed. The oscillator comprises an active element for oscillator and a YIG thin film resonator connected to the active element as a part of feed-back circuit for the active element. The YIG thin film resonator is applied with a bias magnetic field perpendicular to a surfce of a YIG disk which is generated by a permanent magnet for a fixed component and a coil for a variable component for the resonance frequency. The resonance frequency is stabilized by use of a PLL circuit connected to an output of the oscillator and feeding back to the coil. Since the YIG thin film tuned oscillator has a high Q value, high quality communication signal processing can be achieved. The YIG tuned oscillator is used as local oscillator for a transciever.
Abstract:
An oscillator including two magnetostatic wave delay lines of different lengths formed on the surface of a magnetic material, one of whose ends is common and made by a first microstrip coupler, each of the other ends being made of a second and a third microstrip couplers respectively. The two lines are looped by means of a single amplifier. By selecting the two lengths, it is possible to obtain the desired interval between modes in such a way that there is a single oscillation mode comprised in the pass-band of the strips, in a pre-determined tuning band. This oscillator operates in the microwave range.