Tuner
The present disclosure relates to a tuner capable of receiving a television broadcasting signal of a wide band having an operating frequency bandwidth of 48 MHz˜1 GHz, wherein the tuner filters a radio frequency (RF) signal outputted from the low noise amplifier using a tunable filter. The tunable filter includes according to an embodiment an inductor and a variable capacitor as passive elements to reject harmonics. The tuner includes a mixer which mixes an output signal of the tunable filter with a local oscillator signal and converts the mixed signal to an In-phase and Quadrature IF signal, where the converted IF signal of I channel and Q channel is processed through an IF signal processor and is converted to an appropriate signal by a demodulator.
1. A tuner comprising:
an amplifier configured to amplify a radio frequency (RF) signal received by the tuner;
a tunable filter configured to filter an output signal of the amplifier by varying filter characteristics of the tunable filter in response to a channel control signal, the filter characteristics of the tunable filter including filter type characteristics of the tunable filter; and
a mixer configured to generate In-phase and Quadrature IF signals by mixing an output signal of the tunable filter and a local oscillator signal,
wherein the tunable filter comprises:
at least one impedance converter;
at least one filter core coupled to the impedance converter; and
at least one switch configured to selectively input the output signal of the amplifier to either the impedance converter or the filter core according to the channel control signal.
2. The tuner as claimed in claim 1 , wherein the filter characteristics of the tunable filter further include a center frequency of the tunable filter.
3. The tuner as claimed in claim 2 , wherein the tunable filter comprises at least one variable capacitor for varying the center frequency of the tunable filter by varying a capacitance of the variable capacitor in response to the channel control signal.
4. The tuner as claimed in claim 1 , wherein the filer type characteristics of the tunable filter are varied by selectively operating the tunable filter as at least one of a low pass filter, a band pass filter, and a high pass filter according to the channel control signal.
5. The tuner as claimed in claim 1 , wherein the filter core functions as a low pass filter, and the impedance converter functions as a high pass filter.
6. The tuner as claimed in claim 1 , wherein according to the channel control signal, the at least one switch is operated such that the output signal of the amplifier is processed through the impedance converter and the filter core, or through only the filter core.
7. The tuner as claimed in claim 1 , wherein the at least one impedance converter includes a plurality of impedance converters, and the at least one filter core is one filter core positioned between the plurality of impedance converters.
8. The tuner as claimed in claim 7 , wherein according to the channel control signal, the at least one switch is operated such that the output signal of the amplifier is processed through the plurality of impedance converters and the filter core, or through only the filter core.
9. The tuner as claimed in claim 1 , further comprising:
a local oscillator configured to generate the local oscillator signal having a plurality of phases in response to the channel control signal.
10. The tuner as claimed in claim 1 , wherein the tunable filter divides the frequency band of the RF signal into a plurality of frequency bands, and includes a plurality of passive tunable filters coupled in parallel for filtering the RF signal of each frequency band.
11. The tuner as claimed in claim 1 , wherein the tunable filter couples, in a parallel hybrid circuit, an active tunable filter for filtering RF signals of low frequency band and a passive tunable filter for filtering RF signals of high frequency band.
12. The tuner as claimed in claim 11 , wherein the passive tunable filter comprises at least one variable capacitor for varying a center frequency of the tunable filter by varying a capacitance of the variable capacitor in response to the channel control signal.
13. The tuner as claimed in claim 1 , further comprising:
a tone generator configured to generate a tone signal in response to the local oscillator signal; and
a multiplexer configured to select either the output signal of the amplifier or an output signal of the tone generator in response to a switching signal, and to output the selected output signal to the tunable filter.
14. The tuner as claimed in claim 1 , further comprising:
an intermediate frequency (IF) signal processor configured to filtering an output signal of the mixer, to correct errors of IF signals from I channel and Q channel and to output the corrected signals to a demodulator.
15. The tuner as claimed in claim 14 , wherein the IF signal processor produces the channel control signal and adjusts a center frequency or a cut-off frequency of the tunable filter.
16. A tuner comprising:
an amplifier configured to amplify a radio frequency (RF) signal received by the tuner;
a tunable filter configured to filter an output signal of the amplifier by varying filter characteristics of the tunable filter in response to a channel control signal, the filter characteristics of the tunable filter including filter type characteristics of the tunable filter; and
a mixer configured to generate In-phase and Quadrature IF signals by mixing an output signal of the tunable filter and a local oscillator signal, wherein the tunable filter comprises:
a filter core configured to receive the output signal of the amplifier;
an impedance converter coupled to the filter core; and
at least one switch configured to selectively input an output signal of the filter core to either the impedance converter or the mixer according to the channel control signal.
17. A tuner comprising:
a tunable filter configured to filter a RF signal according to a channel control signal, the tunable filter including an impedance converter for receiving the RF signal and a filter core coupled to the filter core, wherein the impedance converter is selectively operated according to the channel control signal so as to vary filter characteristics of the tunable filter for filtering the RF signal; and
a mixer configured to mix an output signal of the tunable filter and a local oscillator signal.
18. The tuner as claimed in claim 17 , wherein the tunable filter further includes another impedance converter coupled between the filter core and the mixer, and both impedance converters are selectively operated together according to the channel control signal so as to vary the filter characteristics of the tunable filter for filtering the RF signal.