摘要:
Communication device comprising a transmitter and a receiver, coupled to antenna means respectively via a transmitter output and a receiver input. For an effective and reliable reduction of transmitter leakage signals occurring at the receiver input corrective signal means are being used, comprising transmitter leakage signal selective amplifying means for selectively amplifying said transmitter leakage signal provided with a transmitter signal reference input being coupled to the transmitter output, a transmitter leakage signal input being coupled to the receiver input and a transmitter leakage signal output being coupled to said transmitter leakage signal input for a negative feed back of said transmitter leakage signals.
摘要:
Mirror suppression circuit and receiver using such mirror suppression circuit comprising a first quadrature signal path coupled between quadrature signal input and output terminals and including an error correction circuit for correction of amplitude and phase errors in a carrier modulated quadrature signal comprising a pair of in-phase and phase quadrature signal components. To obtain a suppression of both amplitude and phase imbalance of said carrier modulated quadrature signal as well as signal amplitude variations, a quadrature output of said error correction circuit being coupled through a first filter circuit for a selection of said quadrature signal to a first quadrature input of an error detection circuit, said first quadrature signal path being coupled prior to said first filter circuit through a second quadrature signal path to a second quadrature input of said error detection circuit, said error detection circuit detecting amplitude and phase errors and providing amplitude and phase control signals to amplitude and phase control inputs of said error correction circuit for a negative feed back of said amplitude and phase errors to said error correction circuit, said amplitude control signal varying with at least one of products Iw*Iref and Qw*Qref and said phase control signal varying with at least one of products Iw*Qref and Qw*Iref, Iw and Qw, respectively Iref and Qref, representing the in-phase and phase quadrature signal components of said quadrature signal at the first quadrature input of the error detection circuit, respectively the in-phase and phase quadrature signal components of a quadrature reference signal occurring at the negative carrier frequency of said quadrature signal at the second quadrature input of the error detection circuit.
摘要:
An arrangement for decoding a stereo multiplex signal, comprising a baseband sum signal (L+R), a difference signal (L-R) which is amplitude-modulated on a suppressed sub-carrier and a pilot signal having a frequency located between the frequency bands of said sum and difference signals, said arrangement having an input for the stereo multiplex signal coupled through parallel stereo sum and difference signal paths to first and second inputs of a dematrix circuit, a synchronous demodulator being included in the difference signal path, a local sinusoidal sub-carrier being supplied to a carrier input of said synchronous demodulator for a synchronous demodulation of said amplitude-modulated difference signal (L-R) into baseband. To maximize stereo channel separation the arrangement is provided with an automatic gain control loop comprising a first mixer stage receiving a reference signal, a signal output thereof being coupled to a second mixer stage, both mixer stages having carrier inputs being supplied with said local sinusoidal sub-carrier for a respective up and down conversion of said reference signal, a signal output of said second mixer stage being coupled through a 6 dB attenuator to a difference circuit providing the difference between the output signal of the attenuator and the reference signal, said difference circuit being coupled to a control input of gain controlled amplifying means for varying the gain of said synchronous demodulator and said first and second mixer stages.
摘要:
Controllable oscillator circuit comprising a regenerative loop which incorporates a cascade circuit of first and second sections each having a controllable gain and a phase shift which is 90° at the oscillation frequency, the first and second sections comprising first and second transconductance amplifiers, respectively, outputs of which are coupled to third and fourth transconductance amplifiers, which are positively fed back from the output to the input, and via first and second capacitors to inputs of the second and first gain controlled amplifiers, said first and second capacitors being coupled in parallel to first and second load resistors, respectively, a tuning control current being supplied to control inputs of the first and second transconductance amplifiers, the output of at least one of the first and second transconductance amplifiers being coupled to an amplitude detection arrangement providing a gain control current for an automatic gain control to control inputs of the third and fourth transconductance amplifiers, said first and third transconductance amplifiers of the first section having a differential pair of first and second output terminals in common, said second and fourth transconductance amplifiers of the second section having a differential pair of third and fourth output terminals in common. In order to provide an oscillator capable of generating sinusoidal signals and tuneable at lower tuning frequencies and operating at lower supply voltages than the above conventional oscillator circuit, said first and second parallel RC filters are coupled between the first and second output terminals and the third and fourth output terminals, respectively, said first to fourth output terminals being respectively coupled to first to fourth DC current paths shunting at least a substantial part of said tuning and gain control currents to a supply voltage.
摘要:
Integrated RC filter comprising a first resistor being coupled to a first capacitor through a first node, a signal input of said integrated RC filter being coupled through one ofthe first resistor and the first capacitor to the first node. To allow for an increase in the RC timeconstant τ of the RC filter without losing signal transparency, amplification means are included between said signal input and said one of the first resistor and the first capacitor having a gain factor substantially larger than unity, said first node being coupled through attenuation means to a signal output, said attenuation means having an attenuation factor substantially corresponding to said gain factor.
摘要:
In order to improve the performance of a feed back comprising a loop filter in terms of loop selectivity, stability and robustness the loop filter is being provided with a slew rate limiter.
摘要:
Receiver comprising a resonance amplifier for selectively amplifying a modulated carrier signal being coupled to signal demodulation means for narrow band demodulation of said carrier signal providing an RF carrier level indicative, first DC signal (A) being supplied to a first input of AGC signal generating means, said resonance amplifier having a cascade of first and second transconductance amplifiers (TC1, TC2) being included in a loop, outputs thereof being coupled via first and second parallel RC filters (R1C1; R2C2) to inputs of the second and first transconductance amplifiers TC1, TC2), respectively, said loop also including means for signal inversion (INV), inputs and outputs of third and fourth transconductance amplifiers (TC3, TC4) being coupled to outputs of said first and second transconductance amplifiers (TC1, TC2), respectively, to effectuate a negative resistance value across said first and second parallel RC filters (R1C1, R2C2), respectively, varying with the gain of said third and fourth transconductance amplifiers (TC3, TC4), fifth and sixth transconductance amplifiers (TC5, TC6) being coupled between inputs and outputs of said resonance amplifier. In order to reduce the overall noise figure of the receiver while allowing optmization in terms of dynamic range and dynamic selectivity, said AGC signal generating means derive first and second control signals (Iq, Id) from said first DC signal (A), said first control signal (Iq) being supplied to gain control inputs of said third and fourth transconductance amplifiers (TC3, TC4) and said second control signal (Id) being supplied to gain control inputs of said fifth and sixth transconductance amplifiers (TC5, TC6), the first and second control signals (Iq, Id) increasing at an increase of the first DC signal (A) and vice versa, the first control signal (Iq) stronger than the second control signal (Id).
摘要:
Communication device comprising a transmitter and a receiver, coupled to antenna means respectively via a transmitter output and a receiver input. For an effective and reliable reduction of transmitter leakage signals occurring at the receiver input corrective signal means are being used, comprising transmitter leakage signal selective amplifying means for selectively amplifying said transmitter leakage signal provided with a transmitter signal reference input being coupled to the transmitter output, a transmitter leakage signal input being coupled to the receiver input and a transmitter leakage signal output being coupled to said transmitter leakage signal input for a negative feed back of said transmitter leakage signals.