High linearity, low noise figure tuner front end circuit
AssigneeSiGe Semiconductor Inc.
InventorsStefan Fulga, Adrian Gradinaru, David Rahn
Life of this patent
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Abstract
A cable tuner front end circuit is disclosed for receiving a radio frequency television input signal and for selectively amplifying the signal in dependence upon a predetermined level of the tuner circuit output signal. The tuner front end circuit having first and second radio frequency paths, where in dependence upon the predetermined level of the output signal, the input signal either propagating along the first path without amplification or the input signal propagating along the second path with low noise amplification. Such that, when amplification is not required the amplifier circuit is disabled thereby offering a savings in tuner circuit power consumption.
Claims29
A television cable tuner front end comprising:
- a front end input port for receiving an input signal;
- a front end output port;
- a first radio frequency path electrically coupled to the front end input port;
- a second radio frequency path electrically coupled to the front end input port;
- a first mixer circuit having a first input port, a first output port and a second input port and disposed within the first radio frequency path for receiving the input signal at the first input port, an oscillating signal at the second input port, and for providing a first output signal at the first output port thereof;
- a low noise amplifier circuit having an input port and an output port and disposed within the second radio frequency path for in a first mode of operation receiving the input signal at the front end input port, for amplifying the input signal within a predetermined frequency band, and for providing an amplified signal at the output port thereof, and in a second mode of operation for other than amplifying the input signal;
- and,
- a second mixer circuit having a first input port, a first output port and a second input port and disposed within the second radio frequency path for in the first mode of operation receiving the amplified signal at the first input port, an oscillating signal at the second input port, and for providing a second output signal at the first output port thereof,
- wherein the first output signal and the second output signal are selectably coupled to the front end output port.
A television cable tuner front end comprising:
- a front end input port for receiving an input signal;
- a front end output port;
- a first radio frequency path electrically coupled for receiving electrical signals from the front end input port;
- a second radio frequency path electrically coupled for receiving electrical signals from the front end input port;
- a first variable attenuator circuit disposed within the first radio frequency path and having an input port, electrically coupled to the first output port, and an output port for providing a first attenuated signal;
- a low noise amplifier circuit having an input port, coupled to the second output port, an output port, and disposed within the second radio frequency path for providing an amplified signal;
- and,
- a mixer circuit having a first input port, a second input port, and an output port, the mixer circuit first input port coupled for receiving the first attenuated signal and the amplified signal, the mixer circuit output port for providing an output signal to the front end output port, and the second input port for receiving an oscillating signal from an oscillator source,
- wherein electrical signals within one and only one of the first radio frequency path and the second radio frequency paths are enabled for provision to the mixer circuit.
A method of controlling a television cable tuner front end having a front end input port comprising the steps of:
- receiving an input signal at the front end input port;
- providing a low noise amplifier circuit electrically coupled to the front end input port;
- when the input signal is above a predetermined threshold signal amplitude mixing the signal without further amplification with a local oscillator signal;
- and,
- when the input signal is below the predetermined threshold signal amplitude providing the signal to the low noise amplifier circuit for amplification before attenuation and mixing thereof.
Dependencies are inferred from the claim text.