Impedence-matched transmitting device having high interference immunity
View Patent ↗According to the present invention, the resistance to interference of a transmitting device, which is particularly embodied as a high frequency transmitter with a transmitter amplifier may be improved, whereby a loss-affected network, for example, in the form of a matching resistance, is coupled to the output of the transmitter amplifier, particularly in the case of low output power of the transmitter amplifier, in order to introduce an impedance-matching at the output of the transmitter amplifier. As such, the reflection of an interference signal coming from a transmitter antenna at the output of the transmitter amplifier can thus be reduced.
1. A transmitting device, comprising:
a transmitted signal generator for generating a transmitted signal;
a transmitter amplifier for amplifying and outputting the amplified transmitted signal at an output of the transmitter amplifier, the transmitter amplifier being connected after the transmitted signal generator;
a directional coupler for decoupling part of an output power of the transmitted signal generated by the transmitter amplifier and for applying the decoupled part of the output power to the transmitted signal generator to enable control of the output power of one of the transmitter amplifier and a modulation performed by the transmitted signal generator to be achieved, the directional coupler being connected after the transmitter amplifier; and
a circuit having a specific impedance which is coupled directly to the output of the transmitter amplifier to match the output of the transmitter amplifier, wherein said circuit does not contain non-reciprocal components, and wherein an impedance of the circuit is chosen so that matching to a wave of an interference signal running in a direction of the output of the transmitter amplifier can be achieved, and a reflection of the interference signal at the output of the transmitter amplifier is accordingly reduced.
2. A transmitting device as claimed in claim 1 , wherein the transmitted signal generator generates a high-frequency transmitted signal.
3. A transmitting device as claimed in claim 1 , further comprising a controllable switch for connecting the circuit with a specific impedance as required in series with the output of the transmitter amplifier and for disconnecting the circuit from the output of the transmitter amplifier.
4. A transmitting device as claimed in claim 3 , further comprising a directional coupler for decoupling part of the transmitted power of the transmitter amplifier, wherein the circuit with the specific impedance may be connected via the controllable switch as required in series between the output of the transmitter amplifier and the directional coupler.
5. A transmitting device as claimed in claim 3 , wherein the circuit with the specific impedance may be connected via the controllable switch as required in series between an output transistor of the transmitter amplifier and the directional coupler.
6. A transmitting device as claimed in claim 3 , further comprising a controller for closing the controllable switch if the output power of the transmitter amplifier is less than a specified limit value, and for opening the controllable switch if the output power of the transmitter amplifier is greater than the specified limit value.
7. A transmitting device as claimed in claim 1 , further comprising a controllable switch for one of switching the circuit with the specific impedance as required parallel to the transmitter amplifier and disconnecting the circuit from the output of the transmitter amplifier.
8. A transmitting device as claimed in claim 7 , wherein the circuit with the specific impedance may be connected parallel to an output transistor of the transmitter amplifier via the controllable switch.
9. A transmitting device as claimed in claim 1 , wherein the impedance of the circuit is formed by a resistor.
10. A transmitting device as claimed in claim 1 , wherein the impedance of the circuit is chosen so that an impedance matching is present at the output of the transmitter amplifier when the circuit is connected to the output of the transmitter amplifier.
11. A transmitting device as claimed in claim 1 , wherein the transmitting device is part of a mobile radio terminal device.