JP2598653B2 - Frequency-voltage conversion circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency-voltage conversion circuit using a semiconductor device that generates a bias voltage for a high-frequency signal by itself.

(Background technology)

Various devices using a p-type semiconductor or an n-type semiconductor are known, including typical devices such as a diode exhibiting a rectifying action, a transistor exhibiting an amplifying action, and the like.
There is also known a variable capacitance diode or the like which positively utilizes a junction capacitance generated when a reverse bias is applied to a junction between the n-type and the n-type, and exhibits a voltage-capacitance conversion action by a phenomenon in which the junction capacitance is changed by a voltage. .

[Configuration of the invention]

The present invention relates to a frequency using the novel semiconductor device 1-
It is intended to provide a voltage conversion circuit, and is provided with a pair of electrode portions 3 which are spaced apart from the n-type or p-type semiconductor portion 2 by a predetermined width and have point-shaped tips which are in point contact with the surface of the semiconductor portion 2. , 4 and
The semiconductor device 1 has a common conducting portion 5 common to input and output, and has one electrode portion 4 and the common conducting portion 5 connected or insulated by a resistor Rs, and the other electrode of the semiconductor device 1. The part 3 is an input terminal 6 to which the high-frequency signal Si is input, and the high-frequency signal is
It is characterized in that a bias amount detection circuit 12 for detecting the bias voltage of So is connected.

In this case, the bias amount detection circuit 12 is connected to the one electrode unit 4
Voltage detection circuit 13 that detects the positive voltage side of the high-frequency signal So output from the
There is provided a negative voltage detection circuit 14 for detecting the negative voltage side of So, and a comparison circuit 15 for comparing the DC output levels of the detection circuits 13 and 14 and obtaining the deviation.

[Function of the invention]

 Next, the operation of the present invention will be described.

Now, as shown in FIG. 3 (a), if a high-frequency signal Si having a DC component of 0 level is supplied to the input terminal 6 and the common conducting portion 5,
A current flows through the floating capacitance Cs between the electrode units 3 and 4, the parallel circuit of the semiconductor unit 2, the resistor Rs in series with the circuit, and the floating capacitance between the semiconductor unit 2 and the common conducting unit 5.
Then, as shown in FIG. 3B or 3C, a negative bias voltage or a positive bias voltage is applied to the potential of the electrode unit 4, that is, the high frequency signal So obtained from the electrode unit 4 and the common conducting unit 5. Occurs. The magnitude of the bias voltage corresponds to the magnitude of the frequency of the high-frequency signal Si, and the polarity of the bias voltage is determined by the conduction type of the semiconductor unit 2. The p-type has a negative side, and the n-type has a positive side. Become.

〔Example〕

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a semiconductor device used in a frequency-to-voltage conversion circuit according to the present invention, FIG. 2 is a block circuit diagram of the frequency-to-voltage conversion circuit, and FIG. 3 is a waveform diagram of signals at various parts in FIG. It is.

First, the configuration of the semiconductor device 1 will be described with reference to FIG.

In the figure, reference numeral 2 denotes a semiconductor unit. The semiconductor portion 2 is formed in a chip shape by selecting a p-type or n-type semiconductor. Also,
Reference numerals 3 and 4 denote a pair of electrode portions which can be formed in the same shape. Each of the electrode portions 3 and 4 has a pointed tip, is substantially parallel to each other, and is brought into point contact with the surface of the semiconductor 2. In this case, the interval between the electrode units 3 and 4 is set so as to have a predetermined floating capacitance Cs.

The electrode section 3 is connected to the input terminal 6, the electrode section 4 is connected to the output terminal 7, and the common conducting section 5 is further provided to form the common terminal 8.

On the other hand, the electrode section 4 and the common conducting section 5 are connected via a resistor Rs. Note that the resistor Rs is built in as necessary, and may be externally attached when the device 1 is used.

Next, a frequency-voltage conversion circuit using the semiconductor device 1 configured as described above will be described with reference to FIG.

In the figure, reference numeral 11 denotes an oscillation circuit whose output frequency is set to a high frequency band of, for example, about 1 to 5 MHz, and is connected to the input terminal 6 of the semiconductor device 1. On the other hand, semiconductor device 1
Is connected to a bias amount detecting circuit 12. The circuit 12 includes a positive voltage detection circuit 13 that detects the potential of the output terminal 7 by a diode connected in the forward direction to the output terminal 7, that is, a positive voltage side of the terminal voltage of the resistor Rs. It comprises a negative voltage detection circuit 14 for detecting the voltage side, and a comparison circuit 15 for comparing the level of the DC output of each of the detection circuits 13 and 14 and obtaining the deviation.
The common terminal 8 is grounded.

In the above circuit configuration, if a high-frequency signal Si having a zero-level bias voltage as shown in FIG. 3A is applied from the oscillation circuit 11 to the input terminal 6 of the semiconductor device 1, the floating electrostatic capacitance between the electrode portions is obtained. A predetermined current flows through a parallel circuit of the semiconductor unit 2 connected to Cs via point contact.

By the way, it should be noted here that when the semiconductor section 2 is of the p-type, the high-frequency signal So of the output terminal 7 as shown in FIG.
Is a point that shifts to the negative side, that is, a negative bias voltage is generated, and in the case of the n-type, it shifts to the positive side, that is, a positive bias voltage is generated as shown in FIG. This phenomenon is caused by the fact that the stray capacitance Cs between the electrode portions and the semiconductor portion 2 are connected in parallel via point contact, and a current flows through the stray capacitance between the semiconductor portion 2 and the common conducting portion 5. It is considered to be an inherent phenomenon caused by the above.

As a result, the negative voltage of the high-frequency signal So becomes large in the case of the p-type having the potential as shown in FIG. 3B, so that the DC output of the negative voltage detection circuit 14 is smaller than the DC output + Va of the positive voltage detection circuit 13. The output −Vb becomes larger (Vb> Va). Therefore, if both outputs are compared in the comparison circuit 15, a deviation on the negative side is obtained.
On the other hand, in the case of the n-type having the potential as shown in FIG.
The DC output + Va of 13 becomes larger than the DC output Vb of the negative voltage detection circuit 14 (Va> Vb). Therefore, if both outputs are compared in the comparison circuit 15, a deviation on the positive side is obtained.

Since the generated bias is caused by the stray capacitance Cs, if the frequency of the high-frequency signal Si is varied, the magnitude of the bias also changes, so that it can function as a frequency-voltage conversion circuit.

The characteristics of the semiconductor device 1 are shown below as an example.

As described above, the embodiments have been described in detail, but the present invention is not limited to such embodiments, and detailed configurations,
Materials and numerical values can be arbitrarily changed and implemented without departing from the gist of the present invention.

〔The invention's effect〕

Thus, the frequency-voltage conversion circuit according to the present invention includes:
It has a pair of electrode portions, each having a predetermined width and spaced apart from the n-type or p-type semiconductor portion by a predetermined width and having a pointed tip at a point contact with the surface of the semiconductor portion, and a common conducting portion common to input and output. And a semiconductor device in which a resistor is connected or insulated between one of the electrode portions and the common conducting portion, and the other electrode portion of the semiconductor device is used as an input terminal for inputting a high-frequency signal. Since a bias amount detection circuit that detects the bias voltage of the signal is connected, a bias voltage corresponding to the magnitude of the frequency of the high-frequency signal input can be generated, and the polarity of the bias voltage depends on the conduction type of the semiconductor portion. Since they can be different, there is a remarkable effect that the circuit can be implemented with a simple circuit at low cost.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a semiconductor device used in the frequency-voltage conversion circuit according to the present invention. FIG. 2 is a block circuit diagram of the frequency-voltage conversion circuit. FIG. 3 is a waveform diagram of signals at various parts in FIG. . In the drawings, 1: semiconductor device, 2: semiconductor part 3, 4: electrode part, 5: common conduction part 6: input terminal, Si: high frequency signal So: high frequency signal, 12: bias amount detection circuit 13: positive voltage detection Circuit, 14: Negative voltage detection circuit 15: Comparison circuit

Claims (2)

(57) [Claims] 1. A pair of electrode portions (3) spaced apart from an n-type or p-type semiconductor portion (2) by a predetermined width and having a pointed tip at a point contact with the surface of the semiconductor portion (2). , (4) and a common conducting part (5) common to the input and the output, and one electrode part (4) and the common conducting part (5) are connected or insulated by a resistor (Rs). A semiconductor device (1), and the other electrode (3) of the semiconductor device (1) is used as an input terminal 6 for inputting a high-frequency signal (Si);
A frequency-voltage conversion circuit comprising a bias amount detection circuit (12) for detecting a bias voltage of a high-frequency signal (So) connected to one of the electrode portions (4). 2. A positive voltage detection circuit (13) for detecting a positive voltage side of a high-frequency signal (So) output from one electrode section (4); A negative voltage detection circuit (14) for detecting the negative voltage side of the high frequency signal (So) output from (4), and each detection circuit (13) and (1)
2. The frequency-voltage conversion circuit according to claim 1, further comprising a comparison circuit for comparing the level of the DC output of 4) and obtaining the deviation.