Low-noise amplifier for a mobile communication terminal

• US 20010029172A1
• Filed: 12/28/2000
• Published: 10/11/2001
• Est. Priority Date: 12/29/1999
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Jae-Min, Lee, Woo-Yong, Park, Se-Young, Cho, Seung-Ki
• Granted Patent: US 6,721,549 B2
• Time in Patent Office: Days
• US Class Current: 455/234.1
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input

Abstract

A low-noise amplifier for a mobile communication terminal maintains linearity with the least current consumption. A low-noise amplifier controller detects a signal-to-noise ratio (SNR) of a received signal, and outputs a control signal of a preset voltage when the SNR is lower than a predetermined SNR even though AGC AMP controller increases the AGC gain according to field strength. A bias circuit increases a bias current according to the control signal output from the low-noise amplifier controller. A low-noise amplifier amplifies the received signal to a preset level according to the bias current provided from the bias circuit.

Claims

1. A receiver for a mobile communication terminal, comprising:

a low-noise amplifier controller for receiving a signal-to-noise ratio (SNR) of a received signal from a MODEM, receiving information about received signal strength indicator(RSSI) from RSSI detector, and outputting a control signal when the SNR has no improvement even though the RSSI is increasing;

a bias circuit for increasing a bias current according to the control signal output from the low-noise amplifier controller; and

an low noise amplifier for amplifying the received signal to a corresponding signal level according to the bias current provided from the bias circuit.

2. The receiver as claimed in

claim 1

, wherein the low-noise amplifier comprises a metal semiconductor field-effect transistor (MESFET).

3. The receiver as claimed in

claim 1

, wherein the bias circuit comprises:

a bipolar junction transistor(BJT) receiving the control signal; and

at least two resistors connected in parallel to a source of the MESFET to control a drain current.

4. The low-noise amplifier as claimed in

claim 1

, wherein the bias circuit comprises:

a bipolar junction transistor(BJT) receiving the control signal; and

at least two resistors connected in serial to a source of the MESFET to control a drain current.