Broadband low-noise low-intermodulation receiver

A low-noise low-intermodulation broadband receiver comprising:

• a low-noise amplifier, receiving an input differential or single-ended radio frequency signal for amplification, having low noise figure, low distortion, input impedance matching, and differential output signal;
• a first buffer, receiving the output of the low-noise amplifier, adjusting DC biasing, generating buffered signal and preventing reverse signal flow;
• a first voltage/current converter, receiving the first buffered output signal, and linearly converting the voltage signal into a current signal;
• an automatic gain control amplifier, receiving the current signal generated by the first voltage/current converter and converting into voltage signal for output, and adjusting the amplification gain based on the gain control signal input by an intermediate frequency output amplitude sensor, for maintaining the output thereof at a designated amplitude level;
• a second buffer, receiving the output signal of the automatic gain control amplifier, adjusting DC biasing, generating buffered signal and preventing reverse signal flow;
• a tracking filter, receiving the output signal of the second buffer and allowing passage therefrom only the component of the radio frequency signal with designated frequency and filtering out all other signal components;
• a second voltage/current converter, receiving the radio frequency signal output by the tracking filter and having designated frequency, and converting the voltage signal into a current signal;
• a phase-locked loop comprising a voltage-controlled oscillator core, a resonator, a third buffer and a phase-locked loop controller, wherein the resonator receiving the control signal of the phase-locked loop to determine an oscillation frequency, the voltage-controlled oscillator core being connected to the resonator for generating an oscillation signal having the oscillation frequency, and the oscillation signal being buffered by the third buffer and input to the phase-locked loop controller, the third buffer receiving the output signal of the voltage-controlled oscillator core, adjusting DC biasing, generating buffered signal and preventing reverse signal flow, and the phase-locked loop controller receiving channel data and generating band switching signal and frequency fine-tuning signal for the phase-locked loop circuitry and the tracking filter;
• a mixer, receiving the signal of the second voltage/current converter and the signal of the third buffer for generating the mixed signal of the two signals;
• a fourth buffer, receiving the output signal of the mixer, adjusting DC is biasing, generating buffered signal and preventing reverse signal flow;
• an intermediate frequency filter, receiving the output of the fourth buffer for generating a final intermediate frequency signal for subsequent signal demodulation;
• wherein the noise figure of the low-noise amplifier determines the low noise figure performance of the receiver apparatus, and the linearity of the low-noise amplifier, the first buffer, the first voltage/current converter and the automatic gain control amplifier maintains the good linearity performance of the receiver and the amplitude of the output of the automatic gain control amplifier at a designated level.