US 6,034,566 A · Tuning amplifier

Abstract

A tuning amplifier 1 is provided with two cascade connected phase shifting circuits 10C and 30C and an adding circuit composed of a feedback resistor 70 and input resistor 74. The circuit 10C is constituted of an operational amplifier 12, a resistor 18 one end of which is connected to the inverting input terminal of the amplifier 18, a resistor 20 connected between the inverting input terminal and the output terminal of the amplifier 12, a series circuit which comprises a capacitor 14 and a variable resistor 16 and one end of which is connected to the other end of the resistor 18. The fluctuation of the output amplitude of the circuit 10C is suppressed when the tuning frequency of the circuit 10C is changed because the resistance of the resistors 18 and 20 are equal to each other. When the signal inputted to a voltage dividing circuit composed of resistors 21 and 23 is taken out as an output, the tuning amplifier 1 itself has a gain and the amplitude of the signal is amplified simultaneously with the tuning operation. The phase shifting circuit 30C has the same structure as that of the circuit 10C, and total phase shift by the circuits 10C and 30C is 360.degree. at a prescribed frequency. Therefore, the tuning amplifier 1 outputs only a signal having a prescribed frequency as a tuned signal.

Claims37

Dependent claims

A tuning amplifier comprising:

an adding circuit for adding an input signal and a feedback signal;
two phase shifting circuits of a full band pass type including a differential amplifier wherein an output is returned to the input side;
and
a voltage dividing circuit interposed into one part of the feedback loop formed by connecting in cascade each of said two phase shifting circuits;
wherein the added signal from said adding circuit is applied to the front stage phase shifting circuit of said two cascade connected phase shifting circuits, the output signal from the subsequent stage phase shifting circuit is applied to said adding circuit as said feedback signal,
and wherein portions of an input signal to the front stage phase shifting circuit are provided to an inverting input and portions of the input signal to the front stage phase shifting circuit are provided to a non-inverting input of the differential amplifier front stage phase shifting circuit, and an AC signal input to said voltage dividing circuit is output as a tuned signal.

3 more elements

A tuning amplifier comprising:

an adding circuit for adding an input signal applied to one end of an input impedance element and a feedback signal applied to one end of a feedback impedance element;
and
two phase shifting circuits including a differential amplifier wherein one end of a first resistor is connected to the inverting input terminal and an AC signal is applied by way of said first resistor, a first voltage dividing circuit connected to the output terminal of said differential amplifier, a second resistor interposed between the output terminal of said first voltage dividing circuit and the inverting input terminal of said differential amplifier, and a series circuit constituted by a reactance element using a capacitor or an inductor and a third resistor and connected to the other end of said first resistor, and wherein the junction point of said third resistor and said reactance element is connected to the non-inverting input terminal of said differential amplifier;
wherein each of said two phase shifting circuits are connected in cascade, the added signal from said adding circuit is applied to the front stage phase shifting circuit of said two cascade connected phase shifting circuits, the output signal from the subsequent stage phase shifting circuit is applied to one end of said feedback impedance element as said feedback signal, and the output of either one of the two phase shifting circuits is output as a tuned signal.

1 more element

A tuning amplifier comprising:

an adding circuit for adding an input signal applied to one end of an input impedance element and a feedback signal applied to one end of a feedback impedance element;
and
two phase shifting circuits including a differential amplifier wherein one end of a first resistor is connected to the inverting input terminal and an AC signal is applied by way of said first resistor, a second resistor interposed between the inverting input terminal and the output terminal of said differential amplifier, a third resistor wherein one end is connected to the inverting input terminal of said differential amplifier and the other end is connected to ground, and a series circuit constituted by a reactance element using a capacitor or an inductor and a fourth resistor and connected to the other end of said first resistor, and wherein the junction point of said fourth resistor and said reactance element is connected to the non-inverting input terminal of said differential amplifier;
wherein each of said two phase shifting circuits are connected in cascade, the added signal from said adding circuit is applied to the front stage phase shifting circuit of said two cascade connected phase shifting circuits, the output signal from the subsequent stage phase shifting circuit is applied to one end of said feedback impedance element as said feedback signal, and the output of either one of the two phase shifting circuits is output as a tuned signal.

1 more element

A tuning amplifier comprising:

an adding circuit for adding an input signal applied to one end of an input impedance element and a feedback signal applied to one end of a feedback impedance element;
a first phase shifting circuit including a differential amplifier wherein one end of a first resistor is connected to the inverting input terminal and an AC signal is applied by way of said first resistor, a first voltage dividing circuit connected to the output terminal of said differential amplifier, a second resistor interposed between the output terminal of said first voltage dividing circuit and the inverting input terminal of said differential amplifier, and a series circuit constituted by a reactance element using a capacitor or an inductor and a third resistor and connected to the other end of said first resistor, and wherein the junction point of said third resistor and said reactance element is connected to the non-inverting input terminal of said differential amplifier;
and
a second phase shifting circuit including a differential amplifier wherein one end of a fourth resistor is connected to the inverting input terminal and an AC signal is applied by way of said fourth resistor, a fifth resistor interposed between the inverting input terminal and the output terminal of said differential amplifier, a sixth resistor wherein one end is connected to the inverting input terminal of said differential amplifier and the other end is connected to ground, and a series circuit constituted by a reactance element using a capacitor or an inductor and a seventh resistor and connected to the other end of said fourth resistor, and wherein the junction point of said seventh resistor and said reactance element is connected to the non-inverting input terminal of said differential amplifier;
wherein said first and second phase shifting circuits are connected in cascade, the added signal from said adding circuit is applied to the front stage phase shifting circuit of said two cascade connected phase shifting circuits, the output signal from the subsequent stage phase shifting circuit is applied to one end of said feedback impedance element as said feedback signal, and the output of either one of said first and second phase shifting circuits is output as a tuned signal.

2 more elements

Dependencies are inferred from the claim text.

Tuning amplifier

Life of this patent

Tuning amplifier

Life of this patent

Abstract

Claims37