Toko, Inc.

Toko Kabushiki Kaisha

Hiroshi Tanigawa

Tsuneo Tohyama

Isao Fukai

Hiroshi Kondo

Satoru Yamane

Shuichi Nakamura

Hiroshi Kondou

Disclosed is a variable output-type constant current source circuit capable of varying its output current in a stepwise manner without the complication in circuit configuration and the increase in size of a semiconductor circuit board for incorporating the circuit therein. The constant current source circuit comprises a first self-biasing type constant current circuitconfigured such that transistors M, Mare operable to cooperatively supply a given voltage across a resistor RS to generate a stabilized current I. In order to vary the output current, the constant current source circuit includes a switching circuit(transistor M) connected in series to a series circuit connecting in series the transistor Mand the resistor RS, and a second constant current circuitconnected in parallel to a series circuit connecting in series the transistor M, the resistor RS and the transistor M. The second constant current circuitis also configured to serve as an activation circuit for the first constant current circuit

Variable output-type constant current source circuit

Disclosed is a constant voltage power supply, which comprises an error amplifier VEA including a transistor Mand a transistor Mhaving the same ratio between channel width and channel length as that of the transistor MThe gate and source of the transistor Mare connected to the gate of a transistor Mto form a current mirror circuit in conjunction with the transistor MFurther, the drain of the transistor Mis connected with a transistor Madapted to be switched in response to an external control signal Sg. For example, when the transistor Mis in ON state, any signal amplification function of the transistor Mis vanished away, and the gain of the error amplifier VEA is lowered. The circuit configuration for changing the gain of the error amplifier VEA makes it possible to strike a balance between high-speed response characteristic in an active mode and operational stability in a sleep mode, and reduce a circuit area required for being formed on an integrated circuit.

Constant voltage power supply

A complete type integrator is disclosed which is designed such that the time-constant thereof can be controlled; wide input and output dynamic ranges can be achieved; operation with low power supply voltage is possible; and no offset voltage is generated. More specifically, the integrator comprises an amplifier circuit having a combination of a first and a second differential amplifier circuit (A1, A2) and connected to the input side of an integrator circuit; and an offset eliminating circuit connected to that portion of the amplifier circuit where the input signal (9) is applied. The offset eliminating circuit comprises a combination of a first, a second and a third current-mirror circuit (B1, B2, B3).

Integrator including an offset eliminating circuit and capable of

A polar leapfrog filter includes at least one polar network. The polar network comprises a differentiator constituted by an operational amplifier having input and output terminals, and a first integrator formed by a first capacitor for providing negative feedback to the operational amplifier and a first variable transconductance amplifier; and a second integrator formed by a second capacitor for providing negative feedback to the first integrator, and a second variable transconductance amplifier. A differentiator is provided at each of the input and output portions of the filter, and a third differentiator is provided immediately preceding the output side differentiator. In the case where two or more said polar networks are incorporated, an additional differentiator is provided between the polar networks. The sum of the number of the circuits constituting the differentiators and the number of the polar networks is selected to be even and equal to the order of the filter. The adjacent ones of the circuits are connected in such a manner that leapfrog type negative feedback is effected, and the differentiators except the output side one are constructed in the form of self negative feedback type.

Polar leapfrog filter

A polar leapfrog filter includes at least one polar network. The polar network comprises a differentiator constituted by an operational amplifier having input and output terminals, and a first integrator formed by a first capacitor for providing negative feedback to the operational amplifier and a first variable transconductance amplifier; and a second integrator formed by a second capacitor for providing negative feedback to the first integrator, and a second variable transconductance amplifier. In the case where two or more said polar networks are incorporated, an integrator is provided between adjacent ones of the polar networks. The total number of all the circuits is selected to be odd and equal to the order of the filter. The adjacent ones of the circuits are connected in such a manner that leapfrog type negative feedback is effected.

A polar leapfrog filter includes at least one polar network. The polar network comprises a differentiator constituted by an operational amplifier having input and output terminals, and a first integrator formed by a first capacitor for providing negative feedback to the operational amplifier and a first variable transconductance amplifier; and a second integrator formed by a second capacitor for providing negative feedback to the first integrator, and a second variable transconductance amplifier. An integrator is provided at each of the input and output stages, and a third integrator is provided immediately preceding the output side integrator. In the case where two or more said polar networks are incorporated, an additional integrator is provided between the polar networks. The total number of all the circuits is selected to be even and equal to the order of the filter. The adjacent ones of the circuits are connected in such a manner that leapfrog type negative feedback is effected, and only the input side integrator is constructed in the form of self negative feedback type.

An all-pass filter includes an adder which comprises a variable conductance amplifier and a capacitor connected to the output terminal thereof. The adder is being arranged to add the output of a band pass filter and an input signal together.

All-pass filter

A variable time-constant differentiator comprises an operational amplifier t which a signal is inputted through a capacitor; and a variable transconductance amplifier connected between an input terminal to which a signal is applied and an 5 output terminal.

Variable time-constant type differentiator

A polar leapfrog filter includes at least one polar network. The polar network comprises a differentiator constituted by an operational amplifier having input and output terminals, and a first integrator formed by a first capacitor for providing negative feedback to the operational amplifier and a first variable transconductance amplifier; and a second integrator formed by a second capacitor for providing negative feedback to the first integrator, and a second variable transconductance amplifier. A differentiator is provided at each of the input and output stages of the filter. In the case where two or more said polar networks are incorporated, an additional differentiator is provided between the polar networks. The total number of all the circuit units constituting the filter is selected to provide odd order and equal order for the filter. The circuit units are connected in such a manner that leapfrog type negative feedback is effected.

An active filter circuit comprises a differentiator constituted by an operational amplifier having an input terminal and output terminal, and a first integrator constituted by a first capacitor and a first variable conductance amplifier for providing negative feedback to the operational amplifier and a first variable conductance amplifier; and a second integrator constituted by a second capacitor and a second variable conductance amplifier for providing negative feedback to the first integrator. The active filter circuit is arranged such that a damping pole is set up at a predetermined frequency by adjusting operating currents of the first and second variable conductance amplifiers.

Active filter circuit

A gain control circuit of the current mirror circuit type in which a current source for a first current mirror circuit is constituted with the output stage of another current mirror circuit. Among the junctions of the first current mirror circuit and the another current mirror circuit, the bias side junction of the first current mirror circuit is used as an input terminal and the other as an output terminal. A predetermined current is supplied to a resistor connected to the emitter of the bias side transistor of the first current mirror circuit to obtain a predetermined gain. Application of a signal to the resistor, which signal is opposite in phase to an input signal, serves to cancel the influence of the input signal to thereby eliminate fluctuations in the gain.

Gain control circuit of current mirror circuit type

A phase comparator which comprises a differential amplifier; and a first and a second active load circuit each comprising a current mirror circuit and from which is derived an output signal which is reversed in phase with respect to the output of the differential amplifier. The outputs of the respective active load circuits are superimposed upon each other through other current mirror circuits, and an output resulting from the superimposition is alternately provided based on rectangular waveform signals which are reversed in phase with respect to each other. By smoothing the output, a DC output corresponding to the phase shift of input signal from the rectangular waveform signals is produced. The phase comparator comprises a combination of transistors and diodes which are cascode-connected to each other, and thus is operable with a predetermined voltage as low a 1 V or less.

Low voltage phase comparator

In a switching circuit device using current mirror circuits, there are provided a first group of current mirror circuits wherein a plurality of signal currents supplied via input terminals are superimposed upon mirror currents and signal currents resulting from the superimposition are derived as new mirror currents; and a second group of current mirror circuits to which the new mirror currents are supplied. The output stages of the second group of current mirror circuits are connected to each other at a common point which in turn is tied to the output stage of a current mirror circuit for supplying a mirror current of a predetermined magnitude. An output terminal is led out of said common point. Bias voltage for said second group of current mirror circuits is controlled so that any desired signal current is selected from said plurality of signal currents.

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Tsurugashima, Japan

Hiroshi Tanigawa