Low noise and high gain low noise amplifier
high-gain and low-noise low noise amplifier (LNA) includes a differential amplifier, a pre-amplifier and an impedance matching network. The differential amplifier includes a first input end and a second input end coupled to a grounded impedance. The pre-amplifier includes an input end and an output end. The impedance matching network is coupled between the first input end of the differential amplifier and the output end of the pre-amplifier for matching an input impedance of the differential amplifier with an output impedance of the pre-amplifier. The present invention provides a LNA structure with low noise, high gain and easy design.
1. A high-gain and low-noise low noise amplifier (LNA) comprising:
a differential amplifier comprising a first input end and a second input end coupled to a grounded impedance;
a single transistor pre-amplifier comprising an input end and an output end wherein a drain of the single transistor is connected to a load; and
an impedance matching network coupled between the first input end of the differential amplifier and the output end of the pre-amplifier for matching an input impedance of the differential amplifier with an output impedance of the pre-amplifier.
2. The high-gain LNA of claim 1 further comprising an input impedance coupled to the input end of the pre- amplifier.
3. The high-gain LNA of claim 1 wherein the pre-amplifier is a common-source single transistor amplifier further comprising:
an impedance-matching load connected to the drain of the transistor; and
a degenerate impedance coupled between the source of the transistor and ground.
4. The high-gain LNA of claim 1 wherein the second input end of the differential amplifier is coupled to a capacitance impedance.
5. The high-gain LNA of claim 1 wherein the differential amplifier has two differential output ends.