Abstract:
A fully integrated, programmable mixed-signal radio transceiver comprising a radio frequency integrated circuit (RFIC) which is frequency and protocol agnostic with digital inputs and outputs, the radio transceiver being programmable and configurable for multiple radio frequency bands and standards and being capable of connecting to many networks and service providers. The RFIC includes a tunable resonant circuit that includes a transmission line having an inductance, a plurality of switchable capacitors configured to be switched into and out of the tunable resonant circuit in response to a first control signal, and at least one variable capacitor that can be varied in response to a second control signal, wherein a center resonant frequency of the resonant circuit is electronically tunable responsive to the first and second control signals that control a first capacitance value of the plurality of switchable capacitors and a second capacitance value of the at least one variable capacitor.
Abstract:
Ein Frequenzsynthesizer nach dem direkten digitalen Synthese-Verfahren besteht aus einem Phasenakkumulator (1) zum zyklischen Inkrementieren eines Phasensignals P um ein am Eingang (3) des Phasenakkumulators (1) anliegendes Phaseninkrement M, einer Speichereinheit (6) mit einer in deren Speicherzellen abgespeicherten Tabelle von Sinusfunktionswerten zur Ermittlung von zu Phasenwerten des Phasensignals P korrespondierenden Sinusfunktionswerten, einem Digital-/Analogwandler (11) zur Wandlung der zeitdiskreten Sinusfunktionswerte in eine quasi analoge, sinusförmige Zeitfunktion und einem Anti-Aliasing-Tiefpassfilter (16) zur Glättung der quasi analogen sinusförmigen Zeitfunktion. Zusätzlich enthält der Frequenzsynthesizer nach dem direkten digitalen Synthese-Verfahren eine Addiereinheit (19), die zwischen der Speichereinheit (6) und dem Digital-/Analog-Wandler (11) zwischengeschaltet ist und den zeitdiskreten Sinusfunktionswerten ein nicht-periodsches Signal (NS) überlagert.
Abstract:
Treibervorrichtung für einen spannungsgesteuerten Oszillator (10), mit einer instabilen Spannungsquelle (14) einem Spannungsregler (22), einem Treiber (18) zur Erzeugung einer Steuerspannung (U2) für den Oszillator (10) und einer Rückkopplungsschleife (20), die den Treiber (18) in Abhängigkeit vom Ausgancssignal (Rf) des Oszillators (10) ansteuert, dadurch gekennzeichnet, daf der Spannungsregler (22) die Rückkopplungsschleife (20) mit Betriebsspannung versorgt, während der Treiber (18) durch die ungeregelte Spannung (Ub) der Spannungsquelle (14) gespeist wird, und daf die Rückkopplungsschleife (20) dazu ausgebildet ist, Spannungsschwankungen der Spannungsquelle (14) mit Hilfe des Treibers (18) zu kompensieren.
Abstract:
An output signal is generated from a DRO. It is mixed with an output signal from a VCO having a predetermined tuning range. A portion of a final output frequency is coupled into a phase locked loop circuit that is phase locked to a reference signal from a crystal reference oscillator. The VCO has a tuning range that compensates for any DRO initial frequency error and drift over temperature and aging. The balance of the bandwidth is used to provide the tuning range on the local oscillator output.
Abstract:
A signal synthesiser arrangement includes a signal generator in the form of a voltage controlled oscillator (VCO) (10) which generates a high frequency source signal under the control of a control unit (16). The synthesiser control unit (16) controls the oscillator (10) to produce an output signal of a given frequency. The output signal of frequency F1 from the oscillator (10) is provided to a signal mixer (12). It is also input to a frequency divider (15), which divides it by a value N1 to produce an "offset frequency" signal F2 which is also provided to the mixer (12). The mixer (12) combines these signals and provides the combined signal to a bandpass filter (11) which filters the combined signal to select and provide one of the "sideband" signals produced by the mixer, i.e. F1 + F2, or F1 - F2, as its output signal F3, while suppressing the unwanted, other sideband signal. The output signal F3 from the filter (11) is further frequency divided by a second value N2 in a further frequency divider (17) to produce a signal of frequency Fout that can be used as a carrier frequency signal for a radio transmitter.
Abstract:
The invention relates to a method of controlling a frequency synthesizer and to a frequency synthesizer having a controllable output signal frequency and comprising a direct digital synthesizer (100) whose output signal is coupled to the input of a phase-locked loop (102). To reduce the settling time of the synthesizer, the direct digital synthesizer (100) comprises means (204) for controlling the frequency of the direct digital synthesizer from a first frequency to a second frequency in accordance with predetermined frequency steps.