Radio frequency front-end circuit for receiver and low noise amplifier thereof

摘要

A RF front-end circuit and a low noise amplifier thereof configured for a receiver are provided. The circuit includes a low noise amplifier and a quadrature passive mixer. The low noise amplifier provides two RF output differential signals to the quadrature passive mixer. The RF signals are down-converted to the differential in-phase baseband signals and the differential quadrature-phase baseband signals. The structure of the RF front-end circuit can avoid the signal and noise interfering between in-phase channel and quadrature-phase channel without using a 25% duty cycle local oscillation generator circuit.

主权项

1. A radio frequency front-end circuit, configured for a receiver, comprising:
a low noise amplifier, having a first input node, a second input node, a first output node, a second output node, a third output node and a fourth output node, respectively receiving a first radio frequency input signal and a second radio frequency input signal differential to each other through the first input node and the second input node, and respectively outputting a first radio frequency output signal, a second radio frequency output signal, a third radio frequency output signal and a fourth radio frequency output signal through the first output node, the second output node, the third output node and the fourth output node; and a quadrature passive mixer, coupled to the first output node, the second output node, the third output node and the fourth output node of the low noise amplifier, and respectively receiving the first radio frequency output signal, the second radio frequency output signal, the third radio frequency output signal and the fourth radio frequency output signal, and mixing with a local oscillation signal to obtain a first baseband signal, a second baseband signal, a third baseband signal and a fourth baseband signal, wherein the low noise amplifier comprises:
a main differential input pair, having a common node, a first and second input nodes and a first and second differential nodes, wherein the first and second input nodes of the main differential input pair respectively receive the first radio frequency input signal and the second radio frequency input signal differential to each other;a main tail current source, coupled between the common node of the main differential input pair and the ground;a first sub differential pair, having a common node, a first and second input nodes and a first and second differential nodes, wherein the common node of the first sub differential pair is coupled to the first differential node of the main differential input pair, the first differential node of the first sub differential pair is coupled to a first output impedance and the first output node of the low noise amplifier, and the second differential node of the first sub differential pair is coupled to a second output impedance and the third output node of the low noise amplifier; anda second sub differential pair, having a common node, a first and second input nodes and a first and second differential nodes, wherein the common node of the second sub differential pair is coupled to the second differential node of the main differential input pair, the first differential node of the second sub differential pair is coupled to a third output impedance and the second output node of the low noise amplifier, and the second differential node of the second sub differential pair is coupled to a fourth output impedance and the fourth output node of the low noise amplifier,wherein the low noise amplifier respectively outputs the first radio frequency output signal, the second radio frequency output signal, the third radio frequency output signal and the fourth radio frequency output signal through the first output node, the second output node, the third output node and the fourth output node.