Low-noise amplifier, in particular for a cellular mobile telephone

• US 20020027475A1
• Filed: 06/21/2001
• Published: 03/07/2002
• Est. Priority Date: 07/12/2000
• Status: Active Grant

• Current Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Belot, Didier
• Granted Patent: US 6,639,468 B2
• Time in Patent Office: Days
• US Class Current: 330/252
• 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: H03F 2203/45316 the AAC comprising one or more discrete inductive elements or coils
• CPC Class Codes: H03F 2203/45386 the AAC comprising one or more coils in the source circuit
• CPC Class Codes: H03F 2203/45554 the IC comprising one or more coils
• CPC Class Codes: H03F 2203/45704 the LC comprising one or more parallel resonance circuits
• CPC Class Codes: H03F 3/191 Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03F 3/45089 Non-folded cascode stages

Abstract

The amplifier includes an input amplifier stage, an output amplifier stage cascode-connected with the input amplifier stage, and a load stage connected to the output stage. The load stage includes a plurality of circuits each including a capacitive component and an inductive component having a Q greater than 10, and having respective different resonant frequencies. All the gain curves respectively associated with all the circuits have, to within a stated tolerance, the same maximum gain value at the resonant frequencies. The gain curves respectively associated with two circuits having respective immediately adjacent resonant frequencies overlap below a threshold 3 dB, to within a stated tolerance, below the maximum gain value.

Claims

1. An amplifier including an input amplifier stage (T1A, T1B), an output amplifier stage (T2A, T2B) cascode-connected with the input amplifier stage, and a load stage (ETCH) connected to the output stage, characterized in that the load stage includes a plurality of circuits (CEA_i, CEB_i) each including a capacitive component (C₁) and an inductive component (L_i) having a Q greater than 10 and having respective different resonant frequencies (F_i), in that all the gain curves (CG_i) respectively associated with all the circuits have, to within a stated tolerance, the same maximum gain value (Gmax) at said resonant frequencies, and in that the gain curves respectively associated with two circuits having respective immediately adjacent resonant frequencies overlap below a threshold at 3 dB, to within a stated tolerance, below said maximum gain value.

2. An amplifier according to claim 1, characterized in that the absolute value of said tolerance is approximately 1 Db.

3. An amplifier according to claim 1, characterized in that all the circuits (CEA_i, CEB_i) are connected in series with the output amplifier stage, in that all the circuits have at their respective resonant frequency (F_i) the same first impedance value, to within a stated tolerance, and in that two circuits associated with two immediately adjacent resonant frequencies have at the median frequency between their two resonant frequencies the same second impedance value equal to half said first impedance value, to within a stated tolerance.

4. An amplifier according to claim 3, characterized in that said tolerance is equal to 20%.

5. An amplifier according to any preceding claim, characterized in that each circuit includes an inductive component (L_i) and a capacitive component (C_i) connected in parallel and in that all the inductive components of all the circuits are identical.

6. An amplifier according to any preceding claim, characterized in that it has a differential structure and the input amplifier stage and the output amplifier stage each include a pair of transistors and in that the load stage (ETCH) includes two identical groups of circuits (CEA_i, CEB_i) connected to the respective transistors of the output amplifier stage.

7. A radio-frequency signal receiver, in particular a cellular mobile telephone, characterized in that it includes an amplifier as defined in any preceding claim.