Radio and tuned receiving circuit thereof

Abstract

The invention provides a radio and a tuned receiving circuit thereof. The radio comprises an antenna circuit and a radio circuit which integrates the tuned receiving circuit, an amplifying circuit and an amplitude modulation local oscillating circuit; the tuned receiving circuit comprises a multistage capacitor array consisting of a trigger, a field effect tube and a capacitor; the output end of the trigger is connected with the grid of the field effect tube, the drain of the field effect tube is connected with the amplitude modulation input, and the source of the field effect tube is connected in series with the capacitor and grounded; the control end of the trigger of the unit circuit of the first stage is connected with a control signal; and the control end of the trigger is connected with the output end of the trigger of the last stage from the unit circuit of the second stage. The tuned receiving circuit is integrated in the radio circuit, and tuned receiving and local oscillating tuning are separated, so the problem of high and low end tracking of an amplitude modulation band in the traditional radio circuit is solved, the number of external components and the complexity of debugging operation are greatly reduced, and tuning in the whole amplitude modulation band is kept with good linearity and resolution.

Description

technical field [0001] The invention relates to a radio, in particular to a tuning and receiving circuit for the radio. Background technique [0002] At present, most of the solutions for multi-band electronic tuning portable radios are radio systems composed of general-purpose traditional bipolar radio circuits and corresponding control circuits. When AM (AM: Amplitude Modulation) signal is received, a tuned receiving circuit composed of varactor diodes located outside the radio circuit is generally used to cover the entire AM band. Such as figure 1 As shown, the radio includes a radio circuit 10, and the radio circuit 10 includes a part of the local oscillator tuning circuit 11 and an AM high-amplification circuit 12. Since the varactor diode 20 cannot be integrated in the radio circuit 10, the number of peripheral components of the radio circuit 10 is large, reliable The reliability is not high, the system has high requirements on peripheral devices, and the debugging i...

AI Technical Summary

Problems solved by technology

like figure 1 As shown, the radio includes a radio circuit 10, and the radio circuit 10 includes a part of the local oscillator tuning circuit 11 and an AM high-amplification circuit 12. Since the varactor diode 20 cannot be integrated in the radio circuit 10, the number of peripheral components of the radio circuit 10 is large, reliable The performance is not high, the system has high requirements on peripheral devices, and the debugging is complicated

[0003] Since the capacitance change of the varactor diode is non-linear, and the tuned receiving circuit and the varactor diode tuned by the local oscillator are controlled by the phase-locked loop circuit at the same time, there is a problem of high- and low-end uniform adjustment in the entire amplitude modulation band, and the whole machine The peripheral adjustment of the

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