Low noise amplifier circuit

A wireless communication device comprising one or more amplifiers wherein each amplifier of the one or more amplifiers is a low noise amplifier for converting a single-ended input signal to a differential output signal, the amplifier comprising:

• a first transistor configured in common-source or common-emitter mode, to receive the single-ended input signal and generate a first part of the differential output signal;
• a second transistor configured in common-source or common-emitter mode, to generate a second part of the differential output signal;
• and
• a third transistor and a fourth transistor, and wherein the third transistor and forth transistor are cross-coupled and connected to the first and second transistors such that:
• a drain or collector of the first transistor is coupled to a gate or base of the fourth transistor via a first capacitor;
• a drain or collector of the second transistor is coupled to a gate or base of the third transistor via a second capacitor;
• the drain or collector of the first transistor is connected to a source or emitter of the third transistor, the drain or collector of the second transistor is connected to a source or emitter of the fourth transistor;
• the drain or collector of the first transistor is coupled to a gate or base of the second transistor directly or via a third capacitor;
• a source or emitter of the first transistor is connected to a first inductor and a source or emitter of the second transistor is connected to a second inductor;
• and
• a load impedance coupled to a drain or collector of the third transistor and a drain or collector of the fourth transistor is configured to convert the differential output signal into a differential output voltage;
• wherein a parasitic ground impedance couples the first inductor and the second inductor of the low noise amplifier to a ground.

A receiver for operating at multiple frequency bands, the receiver comprising:

• one or more radio-frequency filters configured to receive a single-ended input signal and to generate a single-ended output signal;
• one or more amplifiers configured to convert a single-ended input signal, being the single-ended output signal generated from the radio-frequency filter, to a differential output signal, wherein each amplifier of the one or more amplifiers is a low noise amplifier for converting a single-ended input signal to a differential output signal, the amplifier comprising:
• a first transistor configured in common-source or common-emitter mode, to receive the single-ended input signal and generate a first part of the differential output signal;
• a second transistor configured in common-source or common-emitter mode, to generate a second part of the differential output signal;
• and
• a third transistor and a fourth transistor, and wherein the third transistor and forth transistor are cross-coupled and connected to the first and second transistors such that:
• a drain or collector of the first transistor is coupled to a gate or base of the fourth transistor via a first capacitor;
• a drain or collector of the second transistor is coupled to a gate or base of the third transistor via a second capacitor;
• the drain or collector of the first transistor is connected to a source or emitter of the third transistor, the drain or collector of the second transistor is connected to a source or emitter of the fourth transistor;
• the drain or collector of the first transistor is coupled to a gate or base of the second transistor directly or via a third capacitor;
• a source or emitter of the first transistor is connected to a first inductor and a source or emitter of the second transistor is connected to a second inductor;
• and
• a load impedance coupled to a drain or collector of the third transistor and a drain or collector of the fourth transistor is configured to convert the differential output signal into a differential output voltage;
• wherein a parasitic ground impedance couples the first inductor and the second inductor of the low noise amplifier to a ground;
• wherein input impedances of the one or more amplifiers are configured to match output impedances of the one or more radio frequency filters at operating frequencies respectively.