Tuner circuit and digital broadcast receiver with low distortion performance and low power consumption
一种调谐器、电路的技术，应用在带有阻抗电路的放大器、电视、彩色电视等方向，能够解决功耗增大、热量问题、大驱动电流不合需求等问题，达到良好失真性能、低功耗的效果
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no. 1 example
[0138] FIG. 1 is a block diagram showing a schematic configuration of a digital broadcast receiver 100 according to a first embodiment of the present invention. As shown in FIG. 1 , a digital broadcast receiver 100 includes a tuner circuit 1 and a signal processing circuit 3 . The tuner circuit 1 includes a broadband amplifier 11, an RF input filter 12, an RF-AGC amplifier 13, an RF interstage filter 14, a PLL circuit 15, a local oscillator 16, a frequency mixing circuit 17, an IF amplifier 18, an automatic gain control circuit 19 , emitter follower circuit 20 , IF filter 21 , IF-AGC amplifier 22 , A / D converter 23 , digital demodulation circuit 24 , and error correction circuit 25 .
[0139] The broadband amplifier 11 receives a television signal (RF signal) received by the antenna 2, amplifies the signal over a broadband, and outputs the resulting signal. The RF input filter 12 receives the signal output from the broadband amplifier 11, removes unnecessary components from t...
no. 2 example
[0155] FIG. 4 is a block diagram showing a schematic configuration of a digital broadcast receiver 100A according to a second embodiment of the present invention, and is related to FIG. 1 . The digital broadcast receiver 100A includes a tuner circuit 51 and a signal processing circuit 3 . The tuner circuit 51 shown in FIG. 4 is different from the tuner circuit 1 shown in FIG. 1 in that an inverter circuit 52 is newly provided. It should be noted that components in FIG. 4 corresponding to those in FIG. 1 are denoted by the same reference numerals in FIG. 1; therefore, a detailed description thereof will not be given here.
[0156]Referring to FIG. 4 , the inverter circuit 52 inverts the RF-AGC voltage output from the automatic gain control circuit 19 and supplies the resulting voltage to the emitter follower circuit 20 . This circuit configuration is applied to the case of using the inversion-type automatic gain control circuit 19 that lowers the RF-AGC voltage when the recept...
no. 3 example
[0162] FIG. 6 is a block diagram of a schematic configuration of a digital broadcast receiver 100B according to a third embodiment of the present invention, and is related to FIG. 4 . The digital broadcast receiver 100B includes a tuner circuit 71 and a signal processing circuit 3 . The tuner circuit 71 shown in FIG. 6 differs from the tuner circuit 51 shown in FIG. 4 in that a comparison circuit 72 is newly provided. It should be noted that components in FIG. 6 corresponding to those in FIG. 4 are denoted by the same reference numerals in FIG. 4; therefore, a detailed description thereof will not be given here.
[0163] Referring to FIG. 6 , the comparison circuit 72 compares the RF-AGC voltage output from the automatic gain control circuit 19 with a reference voltage, and outputs a voltage to the inverter circuit 52 according to the comparison result.
[0164] FIG. 7 is a block diagram showing the configuration of the comparison circuit 72 shown in FIG. 6 . As shown in FIG...
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