AMPLIFIER

• US 20150097619A1
• Filed: 09/09/2014
• Published: 04/09/2015
• Est. Priority Date: 10/03/2013
• Status: Active Grant

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited, Fujitsu Semiconductor Limited (Fujitsu Limited)
• Inventors: Kawano, Yoichi, Yamaura, Shinji
• Granted Patent: US 9,614,482 B2
• Time in Patent Office: Days
• US Class Current: 330/149
• CPC Class Codes: H03F 1/0266 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/26 Modifications of amplifiers to reduce influence of noise generated by amplifying elements
• CPC Class Codes: H03F 1/32 Modifications of amplifiers to reduce non-linear distortion by negative feedback H03F1/34
• CPC Class Codes: H03F 1/3205 in field-effect transistor amplifiers
• CPC Class Codes: H03F 1/3211 in differential amplifiers
• CPC Class Codes: H03F 1/3276 using the nonlinearity inherent to components, e.g. a diode
• CPC Class Codes: H03F 1/565 using inductive elements
• CPC Class Codes: H03F 2200/165 A filter circuit coupled to the input of an amplifier
• CPC Class Codes: H03F 2200/216 A coil being added in the input circuit, e.g. base, gate, of an amplifier stage
• CPC Class Codes: H03F 2200/246 A series resonance being added in shunt in the input circuit, e.g. base, gate, of an amplifier stage, e.g. as a trap
• CPC Class Codes: H03F 2200/387 A circuit being added at the output of an amplifier to adapt the output impedance of the amplifier
• CPC Class Codes: H03F 2201/3215 To increase the output power or efficiency
• CPC Class Codes: H03F 2203/45541 the IC comprising dynamic biasing means, i.e. controlled by the input signal
• CPC Class Codes: H03F 2203/45552 the IC comprising clamping means, e.g. diodes
• CPC Class Codes: H03F 2203/45554 the IC comprising one or more coils
• CPC Class Codes: H03F 2203/45568 the IC comprising one or more diodes as shunt to the input leads
• CPC Class Codes: H03F 2203/45576 the IC comprising input impedance adapting or controlling means
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03F 3/45179 using MOSFET transistors as the active amplifying circuit H03F3/45278 takes precedence

Abstract

An amplifier includes two input terminals to receive a differential, two-tone transmission signal; two output terminals; a coil having terminals connected with the input terminals respectively, and a center tap; a first transistor having the gate connected with one terminal of the coil, and the output terminal connected with one output terminal; a second transistor having the gate connected with the other terminal of the coil, end the output terminal connected with the other output terminal; a diode having a terminal connected with the center tap; and a bias circuit connected with the other terminal of the diode to output a gate voltage to turn on the first and second transistors. The diode adjusts the terminal voltage depending on a signal level of a double harmonic wave of the transmission signal supplied to the terminal of the diode from the center tap.

Claims

1. An amplifier comprising:

a pair of input terminals configured to receive as input a transmission signal being differential and two-tone;

a pair of output terminals;

a coil configured to have both terminals connected with the pair of input terminals, respectively, and to have a center tap;

a first transistor configured to have a gate connected with one of the terminals of the coil, and an output terminal of the first transistor connected with one of the pair of output terminals;

a second transistor configured to have a gate connected with another of the terminals of the coil, and an output terminal of the second transistor connected with another of the pair of output terminals;

a diode configured to have a terminal connected with the center tap of the coil; and

a bias circuit configured to be connected with another terminal of the diode, and to output a predetermined gate voltage to turn on the first transistor and the second transistor,

wherein the diode adjusts a voltage at the terminal of the diode depending on a signal level of a double harmonic wave of the transmission signal supplied to the terminal of the diode from the center tap of the coil.

2. The amplifier as claimed in claim 1, further comprising:

a capacitor configured to have a terminal connected with a point between the other terminal of the diode and a terminal of the bias circuit, outputting the predetermined gate voltage, and another terminal connected with a. reference potential point,

wherein an inductance of the coil and. a capacitance of the capacitor are set to respective values so that a resonance frequency of the double harmonic wave of the transmission signal input into the input terminal is obtained.

3. The amplifier as claimed in claim 1, wherein the diode and the bias circuit configure a clipping circuit,

wherein the clipping circuit adjusts the voltage at the terminal of the diode by clipping the double harmonic wave supplied to the terminal of the diode from the center tap of the coil so that a signal level of a distortion component included in outputs of the first transistor and the second transistor is less than or equal to a predetermined value for a change of a signal level of the transmission signal.

4. The amplifier as claimed in claim 3, wherein the first transistor and the second transistor have a characteristic about a minimal value of the distortion component being shifted toward a high-output side as the gate voltage is reduced;

wherein the terminal or the diodes is an anode, and the other terminal of the diode is a cathode.

5. The amplifier as claimed in claim 3, wherein the first transistor and the second transistor have a characteristic about a minimal value of the distortion component being shifted toward a high-output side as the gate voltage is increased;

wherein the terminal of the diode is a cathode, and the other terminal of the diode is an anode.

6. An amplifier comprising:

an input terminal configured to receive as input a transmission signal being differential and two-tone;

an output terminal;

a filter con figured to be connected with the input terminal, and to transmit a double harmonic wave of the transmission signal;

a coil configured to have a terminal connected with an output terminal of the filter;

a transistor configured to have a gate connected with an input terminal of the filter, and an output terminal of the transistor connected with the output terminal;

a diode configured fee have a terminal of the diode connected with another terminal of the coil; and

a bias circuit configured to be connected with another terminal of the diode, and to output a predetermined gate voltage to turn on the transistor,

wherein the diode adjusts a voltage at the terminal of the diode depending on a signal level of the double harmonic wave of the transmission signal supplied to the terminal of the diode via the coil.

7. The amplifier as claimed in claim 6, further comprising:

a capacitor configured to have a terminal connected with a point between the other terminal of the diode and a terminal of the bias circuit outputting the predetermined gate voltage, and another terminal connected with a reference potential point,

wherein an inductance of the coil and a capacitance of the capacitor ate set to respective values so that a resonance frequency of the double harmonic wave of the transmission signal input into the input terminal is obtained.