Abstract:
An oscillator (10) comprises temperature compensation circuits (30) and (40), a frequency adjustment circuit (50), and an initial deviation correction circuit (60). A temperature compensation voltage (V1), a temperature compensation voltage (V2), a frequency adjustment voltage (V3) and an initial deviation correction voltage (V4) output from these circuits are selectively added by controlling switches (SW1−SW4) according to control data DC stored in a memory (90), and the sum voltage is supplied to a voltage control oscillation circuit (20) as a control voltage (VA).
Abstract:
A voltage controlled oscillator includes an active element having a first connectin point for connection to a voltage source and an output connection point. A tunable resonator including a first voltage tunable dielectric device is connected to an input of the active element. A first circuit branch is also connected to the active element. The first circuit branch can include a second voltage tunable dielectric device. A tuning voltage controller supplies a control voltage to the first and second voltage tunable dielectric devices to control the frequency of an oscillating voltage at the output connection point. In a reflect type voltage controlled oscillator, the first circuit branch is a bypass circuit. In a transmission type voltage controlled oscillator, the first circuit branch includes a phase shifter and is connected between the active element output connection point and the tunable resonator.
Abstract:
A tunable element in the microwave frequency range includes one or more tunable elements (107). The low noise digital signals filtered by a digital isolation technique are converted to the analog control voltage by way of D/A converter (105). A low cost microwave oscillator (106) and filter are used for directly tune the tunable elements (107).
Abstract:
An oscillator having a tank circuit (L2, CR1, C2, C3, C4), a transistor amplifier circuit (Q1) and a switching circuit (Q2). The switching circuit (Q2) switches the oscillator between a normal power consumption mode and a lower power consumption mode by switching between two selected voltages at the base of the amplifier transistor (Q1). When in the lower power consumption mode, the oscillator has sufficient current to sustain oscillation, but insufficient current to meet the phase noise requirements for good fidelity and high data rates. When in the normal power consumption mode, the oscillator has sufficient current to meet the phase noise requirements.
Abstract:
An electronic oscillator of the Colpitts type with an amplifying element (A) and a tank circuit (T). The tank circuit (T) includes a parallel tuned resonant circuit (PT), a series tuned resonant circuit (ST) and a switching circuit (SW) that selectively connects one of the resonant circuits (PT, ST) to the tank circuit (T). The oscillator operates at a first frequency in the parallel tuned mode and a second frequency that is substantially twice the first frequency in the series tuned mode.
Abstract:
An apparatus for tracking the varying resonant frequency of an electrically resonant structure, characterised by: a variable frequency oscillator providing an excitation signal of a variable frequency encompassing the possible resonant frequency range of said resonant structure, a bidirectional RF transmission line connecting said variable frequency oscillator and said resonant structure, said transmission line incorporating a directional coupler which generates a directional coupler signal proportional to the reflected signal from said resonant structure, said directional coupler signal being conditioned by a processor to provide a feedback signal to the input of the variable frequency oscillator, such that the mean frequency of said excitation signal is caused to continuously track the varying resonant frequency of said resonant structure. Typically the tracking of said varying resonant frequency involves at least two functions, a first search function for initially searching the possible resonant frequency range of said resonant structure and, once resonance of said resonant structure is established, a second following function for following said variable resonant frequency as it varies as a function of time.
Abstract:
Reduction of transmitter exciter chain generated noise from the receive band of a portable/hand-held duplex transceiver is achieved using a high output power, low-noise voltage-controlled oscillator (VCO) in the transmitter exciter chain. Using this high-power, low-noise oscillator as the RF source in the transmitter exciter chain precludes the need for the conventional buffer/driver amplifier stage and an associated inter-stage noise filter. Elimination of buffer/driver stage components and bulky inter-stage noise filter components allows complete integration of transmitter exciter chain components resulting in reduced size and cost.
Abstract:
An electronic viewing aid according to the present invention comprises a small-scale, portable personal radar system adapted to be worn by a person, which radar system includes a miniaturised radar front end assembly (22) operating with millimetre wavelength electromagnetic radiation, an electrical power source, signal processing means and a sensory output means. In a preferred embodiment of the invention, the radar front end assembly (22) is constructed in the form of a pair of spectacles (76), in which both a transmit antenna (78) and a receive antenna (90) of the radar system are carried on respective lens elements (75) of the spectacles (76) and analogue portions of both a transmitter circuit and a receiver circuit are carried on respective side support frames of the spectacles (76); and the sensory output means is an audio output means including stereo headphones (98).
Abstract:
A shielded microstrip assembly (100) includes a substrate (102) having a first ground plane surface (106) and a second surface (206) which includes a transmission line (216). A plurality of solder balls (104) provide electrical interconnection for the ground plane and for the terminals (210) and (212) of transmission line (216). The microstrip assembly (100) is then inverted and attached using solder balls (104) to a carrier (302). The inverted microstrip assembly (100) of the present invention provides for improved shielding, while maintaining the high Q and other advantages associated with a microstrip.
Abstract:
An oscillator (40) comprises a resonator (44) for providing an oscillation frequency for the oscillator, an active network (42), coupled to the resonator, for driving the resonator, and a split-ring resonator (46) coupled to the main resonator and used to provide amplitude and phase balanced outputs. The split-ring resonator has at least a first edge, which is coupled to the resonator, and a second edge. The second edge has a gap (50) therein, and a first terminal located (48) at one side of the gap, and a second terminal (48') symmetrically located at the other side of the gap.