摘要:
The present invention relates to an active band stop filter comprising a filter input and a filter output which are linked by a transmission line LT, a resonator RE coupled to the transmission line and connectable to a load impedance (Q1, L, R, C; C; Varactor). Between the resonator and the load impedance there is mounted a means of activation (CM, diode PIN) of the filtering function in a chosen operating band. The filter is useable in multistandard terminals.
摘要:
The present invention relates to the calibration of a band- rejection filter of a terminal and a multimedia mobile terminal capable of transmitting and receiving signals compliant with several standards in the UHF band. It comprises: a receiver (102) receiving a first signal compliant with a first standard in a first band of frequencies comprised between the frequencies f1 and f2, with f2 > f1, a first transmitter (202b) capable of transmitting a second signal compliant with a second standard in a second band of frequencies comprised between the frequencies f3 and f4, with f3 f3, a band-rejection filter (101 b), upstream of said receiver, in order to, when said first transmitter transmits a second signal, filter said second signal, said band- rejection filter comprising at least one variable element enabling the rejection frequency of said band-rejection filter to be adjusted onto the frequency of said second signal by varying the control voltage of said variable element.
摘要:
Active filter with dual response, comprising a main conductive line between an input port (1) and an output port (2), consisting of an input conductive section, an output conductive section, and an inductance network in series between the input and output conductive sections, the inductance network being coupled to LC resonators, an LC resonator being connected to each junction point between two network inductances, and at least one negative resistance (RN) in series with one of the resonators, wherein the main conductive line, the LC resonators and the negative resistance(s) form an active low-pass filter with a cut-off frequency fc, wherein the active filter comprises a conductive auxiliary line (20), having one end (21) at the filter input side, connected to an electrical ground, and forming a resonator with a resonant frequency fr, less than the cut-off frequency fc of the low-pass filter, the conductive auxiliary line extending from this end, parallel to the main conductive line, and forming by coupling with the main conductive line a rejection filter tuned substantially at said resonant frequency in the low-pass filter bandwidth.
摘要:
The invention relates to a filtering network in HR-Si silicon technology, defined by at least one cut-off frequency FC and comprising an input terminal P1 for receiving the signal to be filtered and an output terminal P2 for delivering a filtered signal. The network comprises a first ground line M1 connected by its ends to first and second ground points Gr1, Gr2 connected directly to the ground plane, a second ground line M2 connected via its ends to third and fourth ground points Gr3, Gr4 directly connected to the ground plane, a plurality of L/C resonant elements Lr1/Cr1, Lr2/Cr2, Lr3/Cr3 connected in parallel and linked via one end to one of the two ground lines L1, L2 and via the other end between them, by means of coupling inductors Ls1, Ls2, Ls3 which thus create transmission zeros. Since each ground line (M1, M2) forms inductive elements (Lm1, Lm2, Lm3) by inductors, the network comprises capacitive elements (Cm1, Cr'1) in series with at least some of said inductive elements (Lm1, Lm2, Lm3), the capacitance of the capacitive elements being chosen so that the resonant frequency of the inductive and capacitive elements in series corresponds to a frequency lying outside the pass band.
摘要:
The channel filter includes at a least one basic bandpass filter (51 ) centred on the frequency of the channel, in series with two cascade-connected reflective filters (50, 60) whose bandwidths are located either side of the basic bandpass filter (51 ) encompassing the channels adjacent to the channel. A reflective filter (50, 60) can include a 90° directional coupler (20) combined with a bandpass filter (F1, F2) designed to ensure transfer (H(p)) matched to the load impedance of the coupler with the input of the bandpass filter connected to a directional coupler (20) output port (22), the input of the directive filter being formed by input port (21 ) of the coupler and the output of the directive filter being formed by a port (ISO, 24) recovering the bandpass filter reflection coefficient (F1, F2). The invention applies in particular to the implementation of the DVB-T and DVB-H standards aimed at receiving digital television programmes from fixed or mobile multistandard terminals such as mobile telephones, PDAs or other multimedia receivers.
摘要:
The invention relates to a selective active low-pass filter and to a method for improving the selectivity of such a filter. The method consists in centring, in the centre of the network, the resonant element whose frequency is closest to the cut-off frequency of the filter and in inserting in series with this element a negative resistance of higher value than the parasitic resistance of the filter.