JP4859353B2 - Amplification circuit and test apparatus - Google Patents

Description

  The present invention relates to an amplifier circuit that amplifies a given input voltage and outputs the amplified input voltage to an external load, and a test apparatus including the amplifier. In particular, the present invention relates to an amplifier circuit that reduces distortion in an amplifier.

  Conventionally, when a given input voltage is amplified and output to an external load, if the load impedance is small, it is necessary to supply a large current to the load. In such a case, an emitter follower circuit is used as a circuit that amplifies the input voltage and supplies it to the load. The voltage gain of the emitter follower circuit is inversely proportional to the emitter resistance of the transistor, and the emitter resistance is inversely proportional to the collector current of the transistor.

  In such a circuit, when the input voltage fluctuates greatly, the current supplied to the load fluctuates and the collector current fluctuates greatly. For this reason, the voltage gain largely fluctuates. When the voltage gain varies greatly according to the amplitude of the input voltage, the signal output to the load is greatly distorted. The same applies when an amplifier other than the emitter follower circuit is used as the amplifier circuit.

  In particular, when operating the amplifier circuit at high speed, it is necessary to reduce the output impedance of the amplifier circuit. However, as described above, when the impedance of the load is small, the amplifier circuit outputs a large current and distortion increases. End up.

  For example, in a test apparatus that tests an electronic device such as a semiconductor circuit, an input signal may be input to the electronic device via an amplifier circuit. At this time, if the input impedance of the electronic device is small, the input signal to the electronic device is greatly distorted as described above, and the electronic device cannot be accurately tested. Also, when the transmission path inside the test equipment is long, the signal may be amplified and transmitted. Even in such a case, the output signal of the amplifier circuit is distorted, and the electronic device must be accurately tested. I could not.

  Therefore, an object of the present invention is to provide an amplifier circuit and a test apparatus that can solve the above-described problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.

  In order to solve the above-described problem, in the first embodiment of the present invention, an amplification circuit that amplifies a given input voltage and outputs the amplified input voltage to an external load, receives the input voltage, and amplifies it with a predetermined amplification factor. An amplifier circuit is provided that includes an amplifier that outputs an output voltage to a load, and a positive-phase current source that is provided in parallel to the amplifier with respect to the load and supplies a current corresponding to the output voltage to the load.

  The positive phase current source may supply the load with a current substantially equal to the output current to be supplied to the load according to the output voltage. The positive-phase current source receives a positive-phase current source resistor having substantially the same impedance as the load, a voltage obtained by inverting the output voltage at the base terminal, the collector terminal is connected to the load and the output terminal of the amplifier, and the emitter terminal is positive. And a positive phase current source transistor connected to the ground potential via a phase current source resistor.

  The positive-phase current source is supplied to the load according to the positive-phase DC current source that supplies at least a part of the current to be supplied to the load according to the DC component of the output voltage to the load and the AC component of the output voltage. And a positive phase alternating current source for supplying at least a part of the power to the load.

  The amplifier is a differential amplifier that outputs a positive-phase output voltage and a negative-phase output voltage to a load. The positive-phase current source supplies a current corresponding to the negative-phase output voltage to the load. The amplifier circuit is a positive-phase output voltage. You may further provide the negative phase current source which supplies the electric current according to an output voltage to load.

  The positive-phase current source receives a negative-phase output voltage at the base terminal, a collector terminal connected to the positive-phase output terminal of the load and the amplifier, and an emitter terminal connected to the positive-phase current source. A negative-phase current source transistor connected to a ground potential through a current source resistor, the negative-phase current source having a negative-phase current source resistor having substantially the same impedance as the load, and a positive-phase output voltage at the base terminal And a negative-phase current source transistor having a collector terminal connected to the load and the negative-phase output terminal of the amplifier, and an emitter terminal connected to a ground potential via a negative-phase current source resistor.

  The positive-phase current source includes a positive-phase DC current source that supplies at least a part of the current to be supplied to the load according to the DC component of the positive-phase output voltage, and a load according to the AC component of the positive-phase output voltage. A positive-phase AC current source that supplies at least a part of the current to be supplied to the load to the load, and the negative-phase current source has at least a current to be supplied to the load according to a DC component of the negative-phase output voltage A negative phase DC current source that supplies a part of the current to the load, and a negative phase AC current source that supplies at least a part of the current to be supplied to the load according to the AC component of the negative phase output voltage. Good. The amplifier circuit may be a circuit that supplies an output voltage to a load having an input impedance of 100Ω or less.

  According to a second aspect of the present invention, there is provided a test apparatus for testing an electronic device, a pattern generator for generating a test pattern for testing the electronic device, and a test input to the electronic device based on the test pattern Based on the waveform shaper that generates the signal, the input unit that is connected to the input terminal of the electronic device and supplies the test signal to the electronic device, and the output signal that the electronic device outputs according to the test signal. And an input unit that receives the test signal and outputs an output voltage amplified at a predetermined amplification factor to the electronic device, and is provided in parallel with the amplifier with respect to the electronic device. And a positive phase current source for supplying a current corresponding to the electronic device to the electronic device.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the scope of claims, and all combinations of features described in the embodiments are included. It is not necessarily essential for the solution of the invention.

  FIG. 1 is a diagram illustrating an example of a configuration of an amplifier circuit 100 according to an embodiment of the present invention. The amplifier circuit 100 is a circuit that amplifies a given input voltage and outputs the amplified input voltage to an external load, and includes an amplifier 10 and a positive phase current source 20.

Amplifier 10, for example an emitter follower circuit, an amplifier such as a differential amplifier circuit receives an input voltage V _in, and outputs the amplified output voltage at a predetermined amplification rate (V _out) to the outside of the load 200.

The positive phase current source 20 generates at least a part of the output current (I _out ) to be supplied from the amplifier 10 to the load 200 according to the output voltage, and supplies the generated current to the load 200. That is, the positive phase current source 20 generates a current that increases or decreases according to the increase or decrease of the output voltage, and supplies it to the load 200. With such a configuration, it is possible to reduce the fluctuation of the current (I _o ) supplied from the amplifier 10 to the load 200 according to the increase or decrease of the output voltage. For this reason, the distortion of the output voltage caused by the fluctuation of the input voltage can be reduced.

The positive phase current source 20 includes a positive phase alternating current source 24, a positive phase direct current source 22, and an inverting circuit 26 provided in parallel with the amplifier 10 with respect to the load 200. The positive-phase DC current source 22 generates at least a part of the current to be supplied to the load 200 according to the DC component of the output voltage and supplies it to the load 200 (I ₂ ). With such a configuration, the burden on the amplifier 10 can be reduced. When the input impedance of the connected load 200 is sufficiently large and it is not necessary to supply a large DC bias current, the amplifier circuit 100 may not include the positive phase DC current source 22.

The positive-phase AC current source 24 generates at least a part of the current to be supplied to the load 200 according to the AC component of the output voltage and supplies it to the load 200 (I ₁ ). The inverting circuit 26 supplies a signal obtained by inverting the AC component of the output voltage to the positive phase AC current source 24, and the positive phase AC current source 24 generates a current corresponding to the voltage supplied from the inverting circuit 26. For example, when the amplifier 10 supplies a positive output voltage to the load 200 and the AC component of the output voltage increases, the positive-phase AC current source 24 increases the current (I ₁ ) supplied to the load 200 and outputs it. When the AC component of the voltage decreases, the positive phase AC current source 24 decreases the current supplied to the load 200.

Further, the positive-phase AC current source 24 may generate a current corresponding to the fluctuation of the output current supplied to the load 200 that fluctuates according to the fluctuation of the output voltage. In this case, the fluctuation of the current output from the amplifier 10 can be made substantially zero, and the distortion of the output voltage can be eliminated. Here, the input impedance of the connected load 200 is preferably known. The positive-phase alternating current source 24 calculates the fluctuation amount of the output current based on the input impedance of the load 200 and the fluctuation of the output voltage, and generates a current corresponding to the fluctuation.

Moreover, it is preferable that the positive phase current source 20 supplies the load 200 with a current substantially equal to the output current (I _out ) to be supplied to the load 200 in accordance with the output voltage (V _out ). In this case, the positive phase direct current source 22 generates a current substantially equal to the direct current component of the output current, and the positive phase alternating current source 24 generates a current substantially equal to the alternating current component of the output current.

  As described above, according to the amplifier circuit 100 in this example, distortion of the output voltage output from the amplifier 10 can be reduced or made substantially zero. Further, even when it is necessary to supply a large current to the load 200, the burden on the amplifier 10 can be reduced or substantially zero.

FIG. 2 is a diagram illustrating another example of the configuration of the amplifier circuit 100. The amplifier circuit 100 in this example includes an amplifier 10, a positive phase current source 20, and a negative phase current source 40. The amplifier 10 in this example is a differential amplifier that outputs a positive phase output voltage (V _out ) to the load 200-1 and outputs a negative phase output voltage (−V _out ) to the load 200-2.

The positive phase current source 20 has a positive phase direct current source 22 and a positive phase alternating current source 24 provided in parallel with the positive phase output terminal of the amplifier 10 with respect to the load 200-1. The positive-phase DC current source 22 has the same function as the positive-phase DC current source 22 described in FIG. 1, and at least a part of the current to be supplied to the load 200 according to the DC component of the positive-phase output voltage. Supply to load 200. The positive phase AC current source 24 generates at least a part of the current to be supplied to the load 200 according to the AC component of the positive phase output voltage of the amplifier 10 based on the AC component of the negative phase output voltage. 200-1 is supplied. With this configuration, like the positive phase current source 20 described in FIG. 1, at least a part of the positive phase output current (I _out ) to be supplied to the load 200-1 is supplied to the load 200-1, and the amplifier The fluctuation of the positive phase current (I _o ) output by the amplifier 10 can be reduced, and the distortion of the positive phase output voltage output by the amplifier 10 can be reduced.

The negative phase current source 40 has a negative phase DC current source 42 and a negative phase AC current source 44 provided in parallel with the negative phase output terminal of the amplifier 10 with respect to the load 200-2. The negative-phase DC current source 42 supplies at least a part of the DC component of the negative-phase output current (−I _out ) to be supplied to the load 200-2 to the load 200-2, similarly to the positive-phase DC current source 22. To do. Thereby, the burden on the amplifier 10 can be reduced.

The negative phase AC current source 44 generates a current to be supplied to the load 200-2 according to the AC component of the negative phase output voltage of the amplifier 10 based on the AC component of the positive phase output voltage of the amplifier 10, Is supplied to the load 200-2. The operation of the negative phase alternating current source 44 is substantially the same as the operation of the positive phase alternating current source 24. With such a configuration, like the normal phase current source 20, at least a part of the negative phase output current (−I _out ) to be supplied to the load 200-2 is supplied to the load 200-2, and the amplifier 10 outputs it. The fluctuation of the negative phase current (−I _o ) can be reduced, and the distortion of the negative phase output voltage output from the amplifier 10 can be reduced.

  In addition, according to the amplifier circuit 100 in this example, each of the positive-phase AC current source 22 and the negative-phase AC current source 44 generates current according to the output voltages of opposite phases, so that the output of the amplifier circuit 100 is Even when noise occurs, the noise can be reduced.

FIG. 3 is a diagram illustrating an example of the configuration of the positive-phase alternating current source 24 and the negative-phase alternating current source 44. The positive phase alternating current source 24 includes a positive phase current source resistor 30 and a positive phase current source transistor 28. The positive phase current source resistor 30 has an impedance substantially equal to the impedance R _{L1 of the} load 200-1 connected to the positive phase output terminal of the amplifier 10 . The positive phase current source transistor 28 receives the AC component of the negative phase output voltage at its base terminal, the collector terminal is connected to the load 200-1 and the positive phase output terminal of the amplifier 10, and the emitter terminal is connected to the positive phase current source resistor 30. To the ground potential. With such a configuration, the AC component of the positive phase output current can be generated based on the negative phase output voltage.

The negative phase alternating current source 44 includes a negative phase current source resistor 50 and a negative phase current source transistor 48. The negative-phase current source resistor 50 has an impedance substantially equal to the impedance R _{L2 of the} load 200-2 connected to the negative-phase output terminal of the amplifier 10. The negative phase current source transistor 48 receives the AC component of the positive phase output voltage at the base terminal, the collector terminal is connected to the load 200-2 and the negative phase output terminal of the amplifier 10, and the emitter terminal is connected to the negative phase current source resistor 50. To the ground potential. With such a configuration, the AC component of the negative phase output current can be generated based on the positive phase output voltage.

  In this example, the positive-phase current source resistor 30 and the negative-phase current source resistor 50 have impedances that are substantially equal to the impedances of the respective loads, but in other examples, they have impedances that are smaller than the impedances of the loads. You may do it. Even with such a configuration, the fluctuation of the current output from the amplifier 10 can be reduced according to the ratio of the impedance of the load and the impedance of the current source resistor. The amplifier circuit 100 may be a circuit that supplies an output voltage to a load having an input impedance of 100Ω or less. The amplifier circuit 100 described with reference to FIGS. 1 to 3 is particularly useful when supplying a voltage to a low-impedance load system.

  FIG. 4 is a diagram illustrating an example of a configuration of a test apparatus 300 according to another embodiment of the present invention. The test apparatus 300 is an apparatus for testing an electronic device such as a semiconductor circuit, and includes a pattern generator 310, a waveform shaper 320, an input unit 330, a timing generator 340, and a determination unit 350.

  The pattern generator 310 generates a test pattern for testing the electronic device 400. Here, the test pattern is an array of numerical values of 1 or 0, for example. The waveform shaper 320 generates a test signal to be input to the electronic device 400 based on the test pattern. For example, the waveform shaper 320 generates a test signal whose voltage level changes according to the test pattern at a timing based on the clock signal.

  The input unit 330 receives the test signal and outputs an output voltage amplified by a predetermined amplification factor to the electronic device 400. The input unit 330 may generate an output voltage using the amplifier circuit 100 described with reference to FIGS.

  The determination unit 350 determines pass / fail of the electronic device based on an output signal output from the electronic device 400 according to the test signal. For example, the determination unit 350 determines pass / fail of the electronic device 400 by comparing the output signal with an expected value signal given from the pattern generator 310. According to the test apparatus 300 in this example, the output voltage to be applied to the electronic device 400 can be generated with high accuracy, so that the test of the electronic device 400 can be performed with high accuracy.

  Further, the test apparatus 300 may use the amplifier circuit 100 described with reference to FIGS. 1 to 3 for transmission of signals inside the test apparatus 300. For example, when the test apparatus 300 has a transmission line having a predetermined length or longer, a signal transmitted through the transmission line may be amplified and transmitted using the amplifier circuit 100.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  As is apparent from the above, according to the present invention, distortion of the output voltage output from the amplifier can be reduced or made substantially zero. Moreover, even when it is necessary to supply a large current to the load, the burden on the amplifier can be reduced or substantially zero.

It is a figure which shows an example of a structure of the amplifier circuit 100 which concerns on embodiment of this invention. 6 is a diagram illustrating another example of the configuration of the amplifier circuit 100. FIG. It is a figure which shows an example of a structure of the positive phase alternating current source 24 and the negative phase alternating current source 44. FIG. It is a figure which shows an example of a structure of the test apparatus 300 which concerns on other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Amplifier, 20 ... Positive phase current source, 22 ... Positive phase direct current source, 24 ... Positive phase alternating current source, 26 ... Inversion circuit, 28 ... Positive phase current source Transistor: 30 ... Positive phase current source resistance, 40 ... Reverse phase current source, 42 ... Reverse phase DC current source, 44 ... Reverse phase AC current source, 48 ... Reverse phase current source transistor 50 ... Reverse phase current source resistance, 200 ... Load, 300 ... Test device, 310 ... Pattern generator, 320 ... Waveform shaper, 330 ... Input unit, 340 ... Timing generator, 350 ... determination unit, 400 ... electronic device

Claims (4)

An amplification circuit that amplifies a given input voltage and outputs the amplified input voltage to an external load,
A differential amplifier that receives the input voltage and outputs a positive phase output voltage and a negative phase output voltage amplified at a predetermined amplification factor to the load;
A positive phase wiring for transmitting the positive phase output voltage to the load;
A negative phase wiring for transmitting the negative phase output voltage to the load;
A positive-phase current source that receives the negative-phase output voltage transmitted through the negative-phase wiring and supplies a current corresponding to the received negative-phase output voltage to the load via the positive-phase wiring;
A negative phase current source that receives the positive phase output voltage transmitted through the positive phase wiring and supplies a current corresponding to the received positive phase output voltage to the load via the negative phase wiring;
The positive phase current source is:
A positive-phase DC current source that is provided in parallel with the differential amplifier with respect to the load and supplies at least a part of the current to be supplied to the load according to a DC component of the positive-phase output voltage to the load; ,
A positive-phase alternating current source that is provided in parallel with the differential amplifier with respect to the load and supplies at least a part of the current to be supplied to the load according to the alternating-current component of the positive-phase output voltage to the load; Have
The negative phase current source is:
A negative-phase direct current source that is provided in parallel with the differential amplifier with respect to the load and supplies at least a part of the current to be supplied to the load according to a direct-current component of the negative-phase output voltage to the load; ,
A negative-phase alternating current source that is provided in parallel with the differential amplifier with respect to the load and supplies at least a part of a current to be supplied to the load according to an alternating-current component of the negative-phase output voltage to the load; Have
The positive phase alternating current source is:
Positive phase current source resistance,
A positive phase current source transistor that receives an alternating current component of the negative phase output voltage at a base terminal, a collector terminal connected to the positive phase wiring, and an emitter terminal connected to a ground potential via the positive phase current source resistance;
Have
The negative phase alternating current source is:
Negative phase current source resistance,
A negative phase current source transistor having a base terminal receiving an AC component of the positive phase output voltage, a collector terminal connected to the negative phase wiring, and an emitter terminal connected to a ground potential via the negative phase current source resistor;
An amplifier circuit.   The positive phase current source resistance has an impedance substantially equal to the load,
  The negative-phase current source resistance has an impedance substantially equal to the load.
The amplifier circuit according to claim 1. The amplifier circuit of claim 1 or 2 for supplying the input impedance is the output voltage below the load 100 [Omega. A test apparatus for testing an electronic device,
A pattern generator for generating a test pattern for testing the electronic device;
A waveform shaper that generates a test signal to be input to the electronic device based on the test pattern;
An input unit connected to an input end of the electronic device and supplying the test signal to the electronic device;
A determination unit that determines the quality of the electronic device based on an output signal that the electronic device outputs in response to the test signal;
The input unit is
It said test signal received as said input voltage, the test apparatus characterized by comprising an amplifier circuit according to the electronic device in any one of claims 1 to 3, operating as the load.

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