JPH0652223U - Current-voltage converter - Google Patents

Abstract

(57) [Abstract] [Purpose] In a current-voltage converter using a current mirror circuit, current input is performed by a constant voltage source, a capacitor and a constant current source without using an amplifying element such as a transistor or FET in the current input section. To do. [Structure] An idling current is supplied by the constant voltage sources VC1 and VC2 and constant current sources CS1 and CS2 provided at the input of the current mirror circuit by CS1 and CS2, and an alternating current input is executed by the VC1 and VC2. By providing the current-voltage conversion resistor R1 at the output of the current mirror circuit,
An alternating voltage is generated across the resistor. Further, by making R1 a variable resistor, it is possible to continuously change the current-voltage conversion rate.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wide band current-voltage converter and amplifier with little distortion caused by a combination of a current mirror circuit, a constant voltage source, a capacitor and a constant current source.

[0002]

[Prior art]

 Conventionally, an amplifying element such as a transistor or an FET is connected to the input of the current mirror circuit that constitutes the current-voltage converter as shown in FIGS. 2, 3, and 4 and used as the current input section.

[0003]

[Problems to be solved by the device]

 These circuits have the following drawbacks. (1) Since transistors and FETs are used with the base and gate grounded, distortion is generated due to the non-linearity of the characteristics of the amplification element. (2) Since transistors and FETs have frequency characteristics, the frequency band and slew rate are limited by the elements. (3) Noise generated by transistors and FETs deteriorates the S / N ratio. (4) It is easily affected by noise from the power source.

[0004]

[Means for Solving the Problems]

 As shown in FIG. 1, constant voltage sources VC1 and VC2 are connected instead of the amplifying elements such as transistors and FETs in the current input section, and capacitors C1 and C2 are connected to the power supply terminals of the current mirror circuits (1) and (2). The current sources CS1 and CS2 are connected, and the bipolar current source BCS is connected to the connection point (3) of VC1 and VC2. Then, by connecting the current-voltage conversion resistor R1 to the connection point (4) of the output part of the current mirror circuit, the alternating current input from BCS is converted into a voltage by R1.

[0005]

[Action]

 In FIG. 1, a bias current I1 is passed from the constant current sources CS1 and CS2 to the current mirror circuits (1) and (2). At this time, the same current flows through the inputs and outputs of the current mirror circuits (1) and (2), so the current I2 flowing through the input and the current I3 flowing through the output are the same, so a current of I1 / 2 flows. . At this time, since the constant current source is connected to the power supply terminal of the current mirror, the impedance is high, and the impedance of the connection point of VC1 and VC2 at connection point (3) is high, I can't enter. Therefore, by connecting C1 and C2 to the power supply terminal of the current mirror circuit, the AC component is grounded and the connection point (3) can be used as a current input. When a bipolar current source BCS is connected to the connection point (3), an alternating current is input to the input of the current mirror circuit, and this current also flows to the output side due to the action of the current mirror circuit. It flows through the voltage conversion resistor R1. At this time, a voltage proportional to the alternating current is generated across R1. The output voltage is the product of the alternating current input from the bipolar current source BCS and the current-voltage conversion resistor R1. At this time, an AC current is input to the current mirror circuit without distortion due to the constant voltage sources VC1 and VC2. Therefore, there is no non-linear distortion due to the characteristics of the amplifying element that occurs when an amplifying element such as a transistor or FET is used as a base ground or a gate ground for current input, and there is no deterioration in frequency characteristics. At this time, if R1 is a variable resistor, the current-voltage conversion rate can be set freely according to the variable resistor. Further, the power supply terminals of the current mirror circuits of (1) and (2) are supplied with currents from the constant current sources CS1 and CS2, and noise is grounded by C1 and C2. A good current-voltage converter is constructed.

[0006]

【Example】

 Example 1 FIG. 5 is an example of an actual current-voltage converter. Transistors Q1 to Q4 are current mirror circuits, D2 and D3 are constant voltage diodes as voltage sources, D1 and D4 are constant current diodes for setting idling current, and R1 is a current-voltage conversion resistor. The D1 and D4 can be replaced with other constant current sources such as FETs and transistors, and the D2 and D3 can be replaced with other voltage sources such as diodes and transistors.

[0007]

【Example】

 Second Embodiment FIG. 6 shows a circuit in which the constant current diodes D1 and D4 in FIG. 5 are replaced with current mirror circuits Q1, Q2, Q7 and Q8.

Embodiment 3 FIG. 7 replaces the current mirror circuit of Q3, Q4, Q5, Q6 of FIG. 6 with a feedback type current mirror circuit of Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10. By doing so, the impedance of the constant current source can be greatly increased and the current-voltage conversion error can be reduced. It is also possible to use another current mirror circuit.

Fourth Embodiment FIG. 8 shows that the circuits of the first to third embodiments have a countermeasure that a constant current source is required on the power supply side of the current mirror circuit and that the current / voltage conversion cannot be performed by DC. Small resistors R2 and R3 are added to the current input section. As a result, the above drawbacks were solved by increasing the idling current that requires the power supply voltage and the product of R2 and R3. The addition of R2 and R3 causes a current-voltage conversion error by that amount, but the error is minimized by adopting a value sufficiently lower than the internal impedance of the bipolar current source BCS.

[0010]

The current-voltage converter and the amplifier have the following effects. (1) The distortion is low because a non-linear amplification element such as a transistor or FET is not used for current input. (2) Since the frequency characteristic is determined only by the characteristics of the stray capacitance and the current mirror circuit, a wide band and a high slew rate can be realized. (3) Since a voltage source is used for current input, noise is hardly generated, and a current-voltage converter or amplifier with good S / N can be configured. (4) By using a variable resistor for R1, it is possible to freely control the current-voltage conversion rate and the amplification degree. Moreover, there is almost no change in the S / N ratio at the position of the variable resistance. (5) Since the number of constituent parts can be reduced, a high-performance current-voltage converter or amplifier can be easily realized. (6) Due to the above features, high-performance current-voltage converters and amplifiers can be constructed without feedback.

[Brief description of drawings]

FIG. 1 is an explanatory view of the present invention.

[Explanation of symbols]

 (1) Current mirror circuit (2) Current mirror circuit (3) Connection point (4) Connection point VC1 constant voltage source VC2 constant voltage source R1 current-voltage conversion resistor + VCC positive power supply −VCC negative power supply OUTPUT output terminal BCS bipolar current source CS1 constant current source CS2 constant current source I1 idling current I2 input idling current I3 output idling current C1 capacitor C2 capacitor

FIG. 2 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

Q1 Transistor configuring current mirror circuit Q2 Transistor configuring current mirror circuit Q3 Transistor configuring current input section Q4 Transistor configuring current input section Q5 Transistor configuring current mirror circuit Q6 Transistor configuring current mirror circuit R1 Current Voltage conversion resistance D1 Bias diode D2 Bias diode + VCC Positive power supply −VCC Negative power supply OUTPUT Output terminal BCS Bipolar current source CS1 Constant current source CS2 Constant current source

FIG. 3 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

Q1 Transistor configuring current mirror circuit Q2 Transistor configuring current mirror circuit Q3 Transistor configuring current input section Q4 Transistor configuring current input section Q5 Transistor configuring current input section Q6 Transistor configuring current input section Q7 Current Transistor forming a mirror circuit Q8 Transistor forming a current mirror circuit R1 Current-voltage conversion resistor + VCC Positive power supply −VCC Negative power supply OUTPUT Output terminal BCS Bipolar current source CS1 Constant current source CS2 Constant current source

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

Q1 transistor forming a current mirror circuit Q2 transistor forming a current mirror circuit Q3 FET forming a current input section Q4 FET forming a current input section Q5 transistor forming a current mirror circuit Q6 transistor forming a current mirror circuit R1 current Voltage conversion resistance + VCC Positive power supply −VCC Negative power supply OUTPUT Output terminal BCS Bipolar current source

FIG. 5 is an explanatory diagram of the first embodiment.

[Explanation of symbols]

Q1 Transistor configuring current mirror circuit Q2 Transistor configuring current mirror circuit Q3 Transistor configuring current mirror circuit Q4 Transistor configuring current mirror circuit D1 Constant current diode D2 Constant voltage diode D3 Constant voltage diode D4 Constant current diode R1 current Voltage conversion resistance + VCC Positive power supply −VCC Negative power supply OUTPUT Output terminal BCS Bipolar current source C1 Capacitor C2 Capacitor

FIG. 6 is an explanatory diagram of the second embodiment.

[Explanation of symbols]

Q1 a transistor forming a current mirror circuit Q2 a transistor forming a current mirror circuit Q3 a transistor forming a current mirror circuit Q4 a transistor forming a current mirror circuit Q5 a transistor forming a current mirror circuit Q6 a transistor forming a current mirror circuit Q7 current Transistor that forms mirror circuit Q8 Transistor that forms current mirror circuit D1 Constant voltage diode D2 Constant voltage diode D3 Constant current diode R1 Current voltage conversion resistor + VCC Positive power supply −VCC Negative power supply OUTPUT Output terminal BCS Bipolar current source C1 Capacitor C2 Capacitor

FIG. 7 is an explanatory diagram of the third embodiment.

[Explanation of symbols]

Q1 a transistor forming a current mirror circuit Q2 a transistor forming a current mirror circuit Q3 a transistor forming a current mirror circuit Q4 a transistor forming a current mirror circuit Q5 a transistor forming a current mirror circuit Q6 a transistor forming a current mirror circuit Q7 current Transistor configuring mirror circuit Q8 Transistor configuring current mirror circuit Q9 Transistor configuring current mirror circuit Q10 Transistor configuring current mirror circuit Q11 Transistor configuring current mirror circuit Q12 Transistor configuring current mirror circuit D1 Constant current diode D2 constant voltage diode D3 constant voltage diode R1 current-voltage conversion resistance + VCC positive power supply −VCC negative electrode Source OUTPUT output terminal BCS bipolar current source C1 capacitor C2 capacitor

FIG. 8 is an explanatory diagram of the fourth embodiment.

[Explanation of symbols]

Q1 Transistor configuring current mirror circuit Q2 Transistor configuring current mirror circuit Q3 Transistor configuring current mirror circuit Q4 Transistor configuring current mirror circuit D1 Constant voltage diode D2 Constant voltage diode R1 Current voltage conversion resistance R2 Small resistance R3 Small Resistance + VCC Positive power supply −VCC Negative power supply OUTPUT Output terminal BCS Bipolar current source

Claims (1)

[Scope of utility model registration request] 1. A resistor connected to a constant voltage source connected to an input of the current mirror circuit, a constant current source connected to a power supply terminal of the current mirror circuit and a capacitor to input a current, and connected to an output of the current mirror circuit. A method of performing current-voltage conversion according to the above, and performing wide-band current-voltage conversion and amplification with little distortion.