Abstract:
PROBLEM TO BE SOLVED: To provide a self-oscillation circuit that oscillates to produce a stable frequency signal with a low driving current.SOLUTION: The self-oscillation circuit includes an oscillation section 1 capable of self-oscillation, and an amplification section 3 for feeding an amplification of a frequency signal of oscillation at the oscillation section 1 back to the oscillation section. A resonator 5 having a resonance frequency in the vicinity of the oscillation frequency of the oscillation section 1 and a higher Q value than the oscillation section 1 is disposed in an oscillation loop including the oscillation section 1 and the amplification section 3. The Q value of the resonator 5 is, for example, at least ten times as large as the Q value of the oscillation section 1.
Abstract:
제어 전압에 따라 위상 시프트를 행하는 위상 제어 회로는 4개의 차동 회로를 포함하는데, 그중 2개는 위상 제어 회로의 위상 시프트 동작용 기본 기능을 제공하는 승산기 회로를 형성하고 나머지 2개는 위상 시프트 동작동안 발생되는 진폭 변동을 소거시킨다. 각각의 차동 회로의 제2바이폴라 트랜지스터의 에미터 면적에 대한 각각의 차동 회로의 제1바이폴라 트랜지스터의 에미터 면적의 비가 2와 3사이의 값으로 설정되는 구성에 의해 진폭 보상이 이루어진다. 대안으로, 진폭 보상은 2개의 차동 회로에 공급된 제어 전압에 오프셋 전압을 제공하는 레벨 시프트 회로에 의해 제공될 수도 있다.
Abstract:
An integrated circuit for driving an oscillator has an amplifier and a feedback network connected to the amplifier. The feedback network comprises a variable resistor. The circuit has first and second terminals for connection to the oscillator crystal, a controller for controlling a setting of the variable resistor and a detector for detecting oscillation for one or more variable resistor settings. This circuit thus provides an embedded system allowing the compatibility between an oscillator crystal and an integrated circuit used for driving the oscillator to be determined. This determination can be made for example in a customer application.
Abstract:
According to the present invention, while maintaining a constant ratio between a bias current supplied to field effect transistors of transconductors 4, 5 and a bias current supplied to field effect transistors of amplifier 3, by controlling oscillation frequency through adjustment of values of bias currents, frequency control can be carried out in much wider range.
Abstract:
In a phase-lock-loop circuit a frequency detector measures a frequency error between an oscillatory signal and a synchronizing signal in alternate horizontal line periods for generating a frequency error indicative signal. The frequency error indicative signal is applied to an oscillator for correcting the frequency error in other alternate horizontal line periods in a manner to prevent frequency error measurement and correction from occurring in the same horizontal line period.
Abstract:
Dispositif de démodulation en fréquence utilisant une boucle à verrouillage de phase. Selon l'invention, pour rendre linéaire la variation de la fréquence d'un oscillateur local (11) en fonction de son signal de commande (Vb), une capacité variable (Cv) est formée par un module électronique (20) qui fournit l'équivalent d'une capacité dont la variation en fonction de la tension de commande (Vb) présente un écart de linéarité établi pour compenser l'écart de linéarité de la fréquence de l'oscillateur en fonction de la valeur de la capacité (Cv). Application : démodulation de signaux modulés en fréquence, notamment de signaux de télévision émis par satellites.
Abstract:
An oscillator arrangement which may be realised largely in integrated-circuit form, in which there is simulated a variable capacitor connected in parallel with an external LC tuned circuit to effect frequency variation of, say, ± 3% centred on 500 MHz in response to a control voltage variation, with 1% linearity. The oscillator comprises two emitter coupled transistor pairs (Q3,Q4;Q5,Q6) and capacitors (C) for coupling the LC circuit to the coupled emitters of the pairs of transistors.