Gain controllable low noise amplifier and wireless communication receiver having the same

Abstract

A gain controllable wide-band low noise amplifier includes a first transistor coupled to an input node and an output node and amplifying an input signal to generate an output signal, a second transistor allowing the output signal to feedback to the input node, and a control circuit complementarily controlling transconductance of the first and second transistors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become readily apparent to those of ordinary skill in the art when descriptions of exemplary embodiments thereof are read with reference to the accompanying drawings.

FIG. 1 is a circuit diagram of a conventional amplifier.

FIG. 2 is a block diagram of a wide-band wireless communication receiver according to an exemplary embodiment of the present invention.

FIG. 3 is a circuit diagram of a gain controllable low noise amplifier according to an exemplary embodiment of the present invention.

FIG. 4 is a circuit diagram of the control circuit of FIG. 3, according to an exemplary embodiment of the present invention.

FIG. 5 is a circuit diagram of a main amplification circuit according to an exemplary embodiment of the present invention.

FIG. 6 is a circuit diagram of a main amplification circuit according to an exemplary embodiment of the present invention.

FIG. 7 is a graph showing the change in the magnitude of the transistor current of the first and second transistors according to a digital control signal in the gain controllable low noise amplifier of FIG. 3.

FIG. 8 is a graph showing the relationship between the gain and the noise figure of the gain controllable low noise amplifier of FIG. 3.

FIG. 9 is a graph showing the input impedance matching of the gain controllable low noise amplifier of FIG. 3.

Claims

1. A gain controllable wide-band low noise amplifier comprising: a first transistor, coupled to an input node and an output node, amplifying an input signal to generate an output signal;a second transistor allowing the output signal to feedback to the input node; anda control circuit complementarily controlling transconductance of the first and second transistors.

2. The low noise amplifier of claim 1, wherein the control circuit comprises: a main control portion controlling the amount of current flowing through the first transistor in response to a control signal; anda feedback control portion complementarily controlling the amount of current flowing through the second transistor with respect to the amount of current flowing through the first transistor in response to the control signal.

3. The low noise amplifier of claim 2, further comprising a third transistor electrically connected to the second transistor and the feedback control portion.

4. The low noise amplifier of claim 3, wherein the main control portion comprises: a first current source supplying a predetermined magnitude of a first reference current;a first current mirror circuit generating a first bias current proportional to the magnitude of the first reference current in response to a complementary signal of the control signal; anda second current mirror circuit electrically connected to the first transistor in a current mirror form and allowing the amount of current flowing through the first transistor to be proportional to the magnitude of the first bias current.

5. The low noise amplifier of claim 4, wherein the feedback control portion comprises: a second current source supplying a predetermined magnitude of a second reference current;a third current mirror circuit generating a second bias current proportional to the amount of the second reference current in response to the control signal; anda fourth current mirror circuit electrically connected to the third transistor in the current mirror form and allowing the amount of current flowing through the second transistor to be proportional to the magnitude of the second bias current.

6. The low noise amplifier of claim 3, further comprising a fourth transistor disposed between the first transistor and the output node.

7. The low noise amplifier of claim 1, further comprising an output load provided between the output node and a power voltage node, the output load including a resistance device and an inductance device electrically connected in series.

8. A gain controllable wide-band low noise amplifier comprising: an amplification portion amplifying an input signal to generate an output signal;a feedback portion allowing the output signal to feedback to an input node; anda control circuit complementarily controlling the amount of current flowing through the amplification portion and the amount of current flowing through the feedback portion.

9. The low noise amplifier of claim 8, wherein the amplification portion comprises an amplification transistor coupled to the input node and an output node, wherein the feedback portion comprises a feedback transistor coupled to the output node and the input node, and wherein the control circuit controls the amount of current flowing through the amplification transistor and the amount of current flowing through the feedback transistor to be inversely proportional to each other.

10. The low noise amplifier of claim 8, wherein the amplification portion comprises an amplification transistor pair coupled to the input node and an output node, wherein the feedback portion comprises a feedback transistor pair coupled to the output node and the input node, and wherein the control circuit controls the amount of current flowing through the amplification transistor pair and the amount of current flowing through the feedback transistor pair to be inversely proportional to each other.

11. The low noise amplifier of either claim 9 or 10, wherein the control circuit comprises: a main control portion controlling the amount of current flowing through the amplification portion in response to a control signal; anda feedback control portion complementarily controlling the amount of current flowing through the feedback portion and the amount of current flowing through the amplification portion in response to the control signal.

12. The low noise amplifier of claim 11, wherein the main control portion comprises: a first current source supplying a predetermined magnitude of a first reference current;a first current mirror circuit generating a first bias current proportional to the magnitude of the first reference current in response to the control signal; anda second current mirror circuit controlling the amount of current flowing through the amplification transistor to be proportional to the magnitude of the first bias current, andthe feedback control portion comprises:a second current source supplying a predetermined magnitude of a second reference current;a third current mirror circuit generating a second bias current proportional to the magnitude of the second reference current in response to the control signal; anda fourth current mirror circuit controlling the magnitude of current flowing through the feedback transistor to be proportional to the magnitude of the second bias current.

13. The low noise amplifier of claim 10, further comprising a fourth transistor disposed between the amplification transistor and the output node.

14. The low noise amplifier of claim 10, further comprising a fourth transistor pair disposed between the amplification transistor pair and the output node.

15. A wide-band wireless communication receiver comprising: a low noise amplifier amplifying an input signal;a mixer down-converting a frequency of an output signal of the low noise amplifier;an A/D converter converting an output signal of the mixer to a digital signal; anda digital signal processor restoring original data from the digital signal,wherein the low noise amplifier includes:an amplification portion amplifying an input signal to generate an output signal;a feedback portion allowing the output signal to feedback to an input node; anda control circuit complementarily controlling the magnitude of current flowing through the amplification portion and the magnitude of current flowing through the feedback portion.

16. The wide-band wireless communication receiver of claim 15, wherein the control circuit comprises: a main control portion controlling the magnitude of current of the amplification portion in response to a control signal; anda feedback control portion complementarily controlling the magnitude of current flowing through the feedback portion with respect to the magnitude of current flowing through the amplification portion in response to the control signal.

17. The wide-band wireless communication receiver of claim 16, wherein the control signal is output from the digital signal processor.