Abstract:
There is disclosed a matching network for connecting an electrically small antenna to an RF source or load. The matching network includes a negative impedance converter, a pre-matching network for connecting the negative impedance converter to the antenna and a post-matching network for connecting the negative impedance converter to the RF source or load. The pre-matching network comprises a combination of capacitors and/or inductors to transform both a real part and an imaginary part of an impedance of the antenna. The negative impedance converter is configured to cancel the transformed imaginary part of the impedance of the antenna. The post-matching network comprises a combination of capacitors and/or inductors to transform a residual real part of the impedance of the antenna to match an impedance of the RF source or load. There is also disclosed an antenna system comprising a plurality of antenna radiating elements each having an associated feed, at least one of the feeds being connected to an RF source or load by way of an active matching circuit comprising a pre-matching network, a negative impedance converter and a post-matching network.
Abstract:
A system comprises a power amplifier configured to amplify an input signal, a splitter configured to split the amplified input signal into a plurality of output signals, a plurality of filters configured to filter the plurality of output signals, respectively, to produce a plurality of filtered output signals, and a combiner configured to combine the filtered output signals to produce a combined output signal.
Abstract:
Analog interference filter devices and methods for isolation of desirable portions of a radio frequency signal. Signal compensation is used to provide desirable center frequency, passband width, ripple, rolloff, stopband and distortion performance. The filter is implemented with passive and/or active components.
Abstract:
An integrated balun includes a low pass filter and a high pass filter that are formed on a semiconductor chip using tunable reactive elements. The outputs of the low pass filter and the high pass filter are tied together to form the single ended output of the balun. The inputs of the low pass filter and the high pass filter form the differential inputs of the balun. The low pass filter and the high pass filter each include a number of tunable networks for achieving the tunable reactive elements. Each tunable network includes at least one switching transistor and at least one fixed value reactive elements. In at least one embodiment, dynamic biasing circuitry may be provided to improve the linearity and reduce the insertion loss of the balun.
Abstract:
A circuit configuration for the bandpass filtering of a high-frequency signal with a large bandwidth, includes a plurality of bandpass filters which have staggered passbands and are disposed in parallel. A changeover switch which is integrated in a semiconductor module is connected to the bandpass filters on the line side. The number of outputs of the semiconductor module is equal to the number of bandpass filters. This improves the circuit configuration with respect to isolation, space requirement, component requirement and costs. Such circuit configurations can be utilized in the field of mobile radio communications.
Abstract:
A power amplifier circuit has a driver amplifier stage including a low band driver amplifier and a high band driver amplifier. A final amplifier stage includes a linear mode amplifier for amplifying digitally modulated signals and a saturated (nonlinear) mode amplifier for amplifying frequency modulated (analog) signals. A switching network interconnects the driver amplifier stage and the final amplifier stage. Depending on the desired mode of operation, an appropriate driver amplifier can be coupled to an appropriate final amplifier to most effectively and efficiently amplify analog or digital RF signals in either of a plurality of frequency bands. A matching circuit is coupled to the linear mode final amplifier for impedance matching and for separating D-AMPS (800 MHz band) and PCS (1900 MHz band) digital signals. A power impedance matching circuit is coupled to the output of the saturated mode final amplifier. In one embodiment, an isolator is coupled to the output of one or more of the low band or high band outputs of the duplex matching circuit. In the low band analog path, a duplexer is provided ahead of the coupling means for reducing the RF power requirements on the coupling means. The switching network and input filter stage may precede a driver amplifier stage.
Abstract:
A signal processor circuit including a plurality of similar cascaded stages, each of which is capable of locking onto and tracking a different frequency of a multiple-frequency composite signal applied to the processor. Each of the stages may comprise a frequency locked loop plus a variable frequency stop, wherein the tuning of the variable frequency stop tracks the output of the frequency locked loop. The variable frequency stop circuit passes the non-locked components to the next similar stage which locks onto one of the remaining components.
Abstract:
A frequency band dividing filter comprises a delay-line filter which is supplied with an input signal and produces a divided frequency band signal as an output, a circuit for deriving a delayed signal in which the input signal has been delayed by a predetermined amount of time, and a circuit for substantially performing subtraction of the delayed signal output signal of the delay-line filter, and producing another divided frequency band output signal. The delay-line filter comprises a plurality of delay circuits cascade connected, coefficient multipliers respectively supplied with the input signal and the output signal of the delay circuits and for multiplying specific coefficients to the signals thus supplied, and an adder for adding output signals of each of the coefficient multipliers.
Abstract:
An electrical frequency filter of the kind having several filter units covering adjacent passbands has negative feedback between adjacent units to tend to cancel unwanted frequencies.