Abstract:
An oscillator includes a plurality of varactor cells to receive a control signal to control a frequency of the oscillator. Each of the varactor cells includes a switch that includes a first terminal to receive the control signal and a second terminal such that the switch operates to control a capacitance of the varactor cell in response to a voltage between the first and second terminals. The oscillator includes a bias circuit to provide a different bias voltage to each second terminal and an amplifier that is coupled to the varactor cells to generate an oscillating signal.
Abstract:
An electronically trimable capacitor (10) having a plurality of branch circuits (30) each including a capacitor (32) which may be selectively controlled by a switch (34) to contribute or not to the net capacitance exhibited by the trimable capacitor (10). Operation of the switches (34) is under direction of an interface (36), which can receive a program signal containing digital instruction for programming via a program terminal (22). An optional memory (38) permits storing a program of states for the switches (34), so that the interface (36) may be instructed to reset the switches (34) and thus cause the trimable capacitor (10) again provide a previously programmed net capacitance, say, in the event of power on or a power loss. An optional enable terminal (24) provides protection against inadvertent programming.
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:
PROBLEM TO BE SOLVED: To provide a crystal oscillator which can be easily integrated by enlarging a frequency variable region. SOLUTION: The crystal oscillator, in which the oscillation capacitors are respectively connected to both ends of a crystal vibrator forming a resonance circuit and grounded to reference potentials, has a constitution, in such a way that an adjusting capacity capable of being freely switched is connected to the capacitors in parallel. At least one of the capacitors is a voltage control type, so as to be used as a variable voltage capacitive element. A variable capacitive element is inserted, either in between connection terminals of the vibrator and the capacitance or in between connection terminals of the vibrator and the parallel circuit of the capacitors to form a voltage control type.
Abstract:
발진기회로는, 모드신호에대한응답으로정상모드와저-전력모드사이에서선택적으로스위칭할수 있다. 정상모드동안, 발진기회로는, 비교적낮은주파수에러를갖는고-정확도클록신호를생성하기위해, 제 1 증폭기구성및 제 1 용량성로딩을이용할수 있다. 저전력모드동안, 발진기회로는, 최소의전력소모를사용하여저-전력클록신호를생성하기위해, 제 2 증폭기구성및 제 2 용량성로딩을이용할수 있다. 보상회로는, 저-전력모드동안비교적높은주파수에러를오프셋하기위해사용될수 있다.
Abstract:
A programmable capacitor bank includes multiple tuning elements (510y). Each tuning element includes two tuning capacitors (513y, 514y) and a pass transistor (516y) that electrically connects or disconnects the capacitors to/from common nodes. (V1z, Vrz, V1y, Vry) For a thermometer decoded capacitor bank, the tuning capacitors for all tuning elements have equal capacitance. (Ct) Each tuning element further includes at least one pull-up transistor (522y, 524y) that provides high bias voltage for the pass transistor and at least one pull- down transistor (526y, 528y) that provides low bias voltage for the pass transistor. The multiple tuning elements may be arranged in a ladder topology such that (1) the tuning elements are turned on in sequential order starting from one end of the ladder and going toward the other end of the ladder and (2) each tuning element receives biasing from a preceding tuning element and provides biasing to a succeeding tuning element. The capacitor bank may be used for VCOs and other circuits.