摘要:
A homodyne receiver is provided for receiving GSM and UMTS transmissions. The receiver may also be used for other transmission schemes. The receiver includes an electronically reconfigurable low pass filter and an off set generator for providing DC offset correction for offsets which may be generated as a result of coupling between a local radio frequency oscillator and the receiver front end.
摘要:
A radio transceiver suitable for use in a mobile telephone is provided. The transceiver is operable in dual modes so as to be able to operate with both GSM and UMTS systems. In a preferred embodiment the transmitter section receives base band signals and up-converts them to an intermediate frequency of approximately 450 MHz. This is then mixed with local oscillator frequency of approximately 1.35 GHz, such that a difference frequency allows operation in the GSM 850/950 MHz band, and the sum frequency allows operation in the GSM 1800/1900 MHz bands. The frequency addition allows operation in the UMTS band. The receiver portion of the transceiver comprises a direct conversion receiver for down-converting the received signal without use of an intermediate frequency.
摘要:
A dual mode transmitter for GSM and UMTS operation is provided. The GSM and UMTS paths share an oscillator and an intermediate frequency stage. Also, with the exception of the final stage of power amplification, the transmitter is provided as an integrated device.
摘要:
Phase-locked loop methods and structures are provided for generating modulated communication signals with nonconstant envelopes. These methods and structures realize the improved communication performance of nonconstant-envelope modulations with the upconversion advantages of phase-locked loops. The structures include transmitters in which a phase-locked loop is augmented with first and second feedforward paths that substantially restore phase and amplitude information to a transmit signal that is generated by a voltage-controlled oscillator of the phase-locked loop. The first feedforward path is configured to realize a path transfer function of s/Kv wherein the voltage-controlled oscillator has a transfer function of Kv/s. The second feedforward path extracts an envelope-correction signal from the modulated intermediate-frequency signal and a variable-gain output amplifier amplifies the transmit signal with a gain that responds to the envelope-correction signal.
摘要:
A direct conversion circuit for radio frequency signals is disclosed. The circuit includes a pair of quadrature related mixers, a phase shift unit, and a local oscillator. The pair of quadrature related mixers is coupled to a radio frequency signal input port for mixing down a radio frequency input signal. The phase shift unit is in communication with at least one of the pair of mixers for phase shifting a local oscillator signal. The local oscillator produces the local oscillator signal. The local oscillator includes a non-integer frequency multiplier for multiplying the frequency of a first voltage controlled oscillator signal by a non-integer value to produce the local oscillator signal.
摘要:
A bridge circuit configured for connection between a tuner circuit capable of receiving broadcast analogue frequencies and a general purpose processor capable of demodulating the received broadcast signal, the circuit comprising: a tuner interface capable of receiving at least one signal component in analogue form from tuner circuitry; an analogue to digital converter connected to receive the analogue signal from the tuner interface and convert it to a digital signal for filtering; a digital filter connected to receive and filter the digital signal; an external digital interface; and a microcontroller arranged to receive control information via said external digital interface, wherein one or more or the analogue to digital converter and the digital filter is provided with a controllably variable clock input.
摘要:
A sinewave oscillator and a quadrature phase shift network fabricated as an integrated circuit for a Barber radio receiver comprising, in order that the network and oscillator be simply adjustable to provide an accurate 90.degree. shift and a sinewave of accurate frequency and high spectral purity, a first capacitance means (C1, C2; C4, C5) coupled to the input of a gyrator (G1; G2) comprising first and second amplifiers (10, 12; 22, 24) connected in feedback configuration with a capacitance (C3; C6) connected to the output of the first amplifier. The oscillator network may be adjusted by current control of transconductance of the amplifiers, and the amplifiers include input signal limiting means to limit the input signal to a linear operating region. An output load resistance (R) may be simulated using a further amplifier connected in feedback configuration.
摘要:
A broadcast receiver system comprising: a tuner circuit operable to detect a plurality of modulated radio frequency signals, including TV broadcast signals, and comprising at least one signal path each comprising an analogue mixer and analogue filter circuitry arranged respectively to frequency convert and pre-select received analogue signals; further circuitry comprising an analogue to digital converter and digital filter circuitry; a data interface to a software demodulation module operable to engage a general purpose processor of a computer in data demodulation and decoding functions; a control, interface; and a microcontroller arranged to receive control information from said computer via the control interface.
摘要:
An interface circuit configured to connect between (a) a broadcast receiver tuner and associated circuitry for the receiving and processing of broadcast radio frequency signals, and (b) a general purpose computer device programmed with software demodulation code configured to engage a general purpose processor in signal demodulation functions, the interface circuit comprising: a data interface comprising a packetisation buffer connected to receive (i) digital signal sample data from a signal path of the tuner and associated circuitry and (ii) indications of control settings which are applied to one or more configurable components during taking of the sample data, said packetisation buffer being operable to construct packets comprising blocks of sample data and header information carrying said control settings indications; a control interface configured to receive control instructions from tuner control code running on the general purpose computer device; and a microcontroller operable to receive the control instructions from the control interface and distribute corresponding control settings to configurable components of the tuner and associated circuitry, said microcontroller also being operable to supply indications of relevant control settings to said packetisation buffer.
摘要:
A direct conversion circuit for radio frequency signals is disclosed. The circuit includes a pair of quadrature related mixers, a phase shift unit, and a local oscillator. The pair of quadrature related mixers is coupled to a radio frequency signal input port for mixing down a radio frequency input signal. The phase shift unit is in communication with at least one of the pair of mixers for phase shifting a local oscillator signal. The local oscillator produces the local oscillator signal. The local oscillator includes a non-integer frequency multiplier for multiplying the frequency of a first voltage controlled oscillator signal by a non-integer value to produce the local oscillator signal.