Signal amplification device with circuit maintaining potential of input side of current mirror circuit at predetermined value

• US 6,642,792 B2
• Filed: 03/21/2002
• Issued: 11/04/2003
• Est. Priority Date: 03/29/2001
• Status: Expired due to Term

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Takahashi, Tatsuya, Takeuchi, Seiji
• Primary Examiner(s): Shingleton, Michael B.
• Application Number:
  US10/104,642
• Publication Number:
  US 20020140508A1
• Time in Patent Office: 593 Days
• Field of Search: 330/257, 330/288
• US Class Current: 330/257
• CPC Class Codes: H03F 1/02 Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
• CPC Class Codes: H03F 1/301 in MOSFET amplifiers H03F1/303, H03F1/305, H03F1/308 take precedence
• CPC Class Codes: H03F 2200/375 Circuitry to compensate the offset being present in an amplifier
• CPC Class Codes: H03F 2200/91 the amplifier has a current mode topology
• CPC Class Codes: H03F 3/345 with field-effect devices H03F3/347 takes precedence

Abstract

A differential amplifier circuit section (10), which realizes a reduction in power consumption of a signal amplification device, converts an input voltage signal into a current signal and then outputs the signal to a current mirror circuit section (12). Because an input-side current path of the current mirror circuit section (12) does not include a resistor and a current signal is not converted into a current signal at an output terminal (14) of the differential amplifier circuit section (10), a power supply voltage (V_DD) can be reduced to the value of product of source-drain voltages of transistors (MP2, MN2, and MN3). The current signal supplied to the input-side current path of the current mirror circuit section (12) is mirrored in the output-side current path and is then converted into a voltage signal through a resistor (R_L) disposed in the path to be generated from an output terminal (18).

Claims

1. A signal amplification device comprising:

a differential amplifier circuit which generates a first output according to an input signal; and

a current mirror circuit which receives thc first output of the differential amplifier circuit to an input-side current path and generates a mirror current through an output-side current path in accordance with a current flowing through the input-side current path, wherein

the mirror current is converted into an output voltage by a resistive load in the output-side current path of the current mirror circuit, and

the current mirror circuit comprises a potential setting circuit which maintains the potential of the input side at a predetermined value.

2. The device according to claim 1, wherein the current mirror circuit comprises a constant-current source which supplies a constant current to the input-side current path such that a current signal from the differential amplifier circuit is superimposed on the supplied current from the constant-current source to form an input-side current.

3. The device according to claim 1, wherein the current mirror circuit comprises, as the sole transistor in the output-side current path, a mirror current generating transistor which is connected to the input-side current path for generating the mirror current.