JPH10173136A - Protection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a protection circuit which greatly elevates the surge level, and does not deteriorate the element characteristics. SOLUTION: A bias circuit having an input terminal 1 connected to the gate of arm FET 10 and output terminal 2 connected to the source comprises a diode 5 and inductance 32 connected in series between the input terminal 1 and ground terminal, such that the RF component of an input signal to the input terminal 1 is inputted to the gate of the FET 10, while the surge frequency component flows to the ground terminal through the diode 5 and inductance 32, thus protecting the circuit from the surge voltage, without giving influence on the characteristics of the FET 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a radio frequency signal (RF)
Signal protection circuit, especially GaAs FET (FIEL
D EFFECT TRANSISTOR), HEMT (HIGH ELECTRON MO
BILITY TRANSISTOR), HBT (HOT ELECTRON TRANSIS
TOR), a junction FET, a silicon high-frequency bipolar transistor, a silicon high-frequency MOSFET, and the like, which are suitable for a surge protection circuit on the input side or output side, or the input / output side of an ultra-high frequency semiconductor active element.

[0002]

2. Description of the Related Art FIG. 18 shows a configuration of a bias circuit using an FET. The gate of the N-channel MOS transistor 10 is connected to the input terminal 1 and the drain is connected to the output terminal 2.
And the source is grounded. A power supply 3 (-1 V) is connected between the gate and the source, a power supply 4 (2 V) is connected between the drain and the source, and a DC bias is applied to each. A high-frequency signal is input from the input terminal 1, and the high-frequency signal is output from the drain.

FIG. 19 shows a vertical section of an element of this bias circuit. On the surface of the GaAs semi-insulating substrate 11, n ⁺ -type impurity regions 16 and 18 and a channel region 17 are formed. Drain electrodes 13 and 15 are formed on the impurity regions 16 and 18, and a gate metal 12 is formed on the channel region 17. The gate electrode 14 is further formed on the gate metal 12.

However, when the signal input to the FET is in the SHF band, the channel depth is as thin as 0.1 μm and the gate electrode length is as extremely small as about 0.2 μm. There's a problem. Therefore, as shown in FIG. 20, there is a conventional circuit in which a PN junction type Zener diode 5 is connected as a protection circuit on the input side, that is, between the gate and the source of the transistor 10.

FIG. 21 is a longitudinal sectional view of the device shown in FIG. In addition to the vertical sectional structure of FIG.
A p ⁺ -type impurity region 21 and an n ⁺ -type impurity region 22 are formed on the surface of the substrate 11 so that the ends thereof overlap, and the diode 5 is formed. A diode source electrode 25 and a diode drain electrode 26 are formed on the p ⁺ -type impurity region 21 and the n ⁺ -type impurity region 22, respectively.
Are connected by a wiring 23, and the diode drain electrode 26 and the source electrode 15 are connected by a wiring 24.

The high-frequency gain Ga in this case is proportional to the reciprocal of the parasitic capacitance Cgs between the gate and the source on the input side. The high frequency noise NFmin is proportional to the capacitance Cgs. For this reason, as can be seen from FIGS. 5 and 6 showing the simulation results, when the diode 5 is provided as shown in FIG. 20, the noise figure (NFmin) is higher than when the diode 5 is not provided as shown in FIG. And high frequency gain (G
ain) is greatly deteriorated. In addition, when the diode 5 is provided, when the protection diode 5 is broken, the insulation between the gate and the source of the transistor 10 is broken and short-circuited, so that there is a problem that the circuit does not operate.

For this reason, in many cases, a circuit is configured as shown in FIG. 18 without using a diode.
The surge withstand voltage was low, and it was easily destroyed when touched or transported by workers.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a protection circuit that significantly improves surge levels and does not deteriorate the characteristics of elements.

[0009]

A protection circuit according to the present invention is connected between an input terminal of a circuit for processing a high-frequency signal and a ground terminal. The high frequency signal component passes through the circuit and does not pass through the ground terminal, and the surge frequency component passes through the ground terminal without passing through the circuit.

Alternatively, a protection circuit according to the present invention is connected between an output terminal of a circuit for processing a high-frequency signal and a ground terminal, and converts a high-frequency signal component of a signal output from the circuit. A surge frequency component is passed through the ground terminal without passing through the output terminal and through the output terminal without passing through the ground terminal.

Here, the protection circuit may be configured such that a capacitance and an inductance are connected in series between the input terminal and the ground terminal or between the output terminal and the ground terminal, or that the capacitance, the inductance and the resistance are different. It may be connected in series, or, between the input terminal and the ground terminal, or between the output terminal and the ground terminal, a capacitance and an inductance are connected in parallel, or an inductance and a resistance are connected in series. The connected one and the capacitor may be connected in parallel.

Further, the protection circuit may be provided with a high-pass filter including a capacitance and a resistance between the input terminal and the ground terminal or between the output terminal and the ground terminal. An input terminal and the ground terminal,
Alternatively, between the output terminal and the ground terminal, a capacitor having a capacitance and an inductance connected in parallel and a capacitor may be connected in series.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is directed to a device in which a high frequency signal (RF signal) is passed through the element side and not through a ground terminal, but a surge frequency component, which is a low frequency signal of about 1 kHz to 1 MHz, is passed through the ground terminal. It is characterized in that it is a protection circuit that does not pass through. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a configuration of a high-frequency device circuit including a protection circuit according to a first embodiment of the present invention. The input side of the bias circuit shown in FIG.
A PN junction type Zener diode 5 and a spiral inductance 32 are connected in series between the ground terminal 2 and the ground terminal 2. FIG. 2 shows a vertical sectional structure of the element in this case. In FIG. 21 showing the element structure of the circuit of FIG. 20 in which only the diode 5 is connected to the input side, the source electrode 15 of the n ⁺ -type impurity region 18 and the n of the diode 5
A spiral inductance 42 is further provided between the wiring 41 and the diode drain electrode of the + type impurity region 22.
43 are connected.

FIG. 3 shows the frequency dependence of the conductance G in the protection circuit according to the first embodiment.
The capacitance C is 100 pF, the inductance L is 100 pH,
If the resonance frequency f ₀ = 1 / 2π (LC) ^0.5 , the resonance frequency f ₀ is 1.6 MHz. Further, when the parasitic capacitance and the resistance included in the inductance 32 are considered, the width of the resonance waveform is increased as shown in FIG.
A surge frequency of 1 MHz from z is included.
Conversely, for a DC bias voltage and a high frequency signal (RF signal) of, for example, about 12 GHz, the conductance G is zero.
And hardly passes through this protection circuit. Accordingly, the high-frequency signal input from the input terminal 1 is input to the gate of the FET 10 without passing through the diode 5 and the inductance 32, and the surge frequency component flows to the ground terminal through the diode 5 and the inductance 32 and FE
No signal is input to the gate of T10. As a result, the element can be protected from surge voltage without affecting the intrinsic characteristics of the element. Further, even if the diode 5 is broken, the effect is obtained that the impedance of the input terminal 1 does not deteriorate and the high-frequency characteristics do not deteriorate because the inductance 32 is connected.

The surge immunity, noise figure, and high frequency gain of the conventional circuit shown in FIG. 18, the conventional circuit shown in FIG. 20, and the circuit according to the first embodiment shown in FIG. The simulation results are shown in FIGS.
And FIG. According to the first embodiment, the surge immunity is improved in the same manner as the circuit of FIG. 20 to which the diode is added, than the circuit of FIG. 18 to which the protection circuit is not added. The noise figure is degraded by the circuit of FIG. 20 to which a diode is added, but is similar to the circuit of FIG. 18 without a protection circuit in the first embodiment, and does not affect the characteristics of the elements. Recognize. Similarly, the high-frequency gain is deteriorated in the circuit of FIG. 20 to which a diode is added, and in the first embodiment, the protection circuit is not added in FIG.
The characteristics similar to those of the circuit of FIG.

In the first embodiment, a protection circuit including the diode 5 and the inductance 32 is provided on the input side of the FET 10. However, as shown in FIG. 7, a diode 51 and an inductance 52 may be connected in series between the output side of the FET 10, that is, between the output terminal 2 and the ground terminal. In this case, even if a signal containing a surge frequency component at the output terminal 2 is input to the FET 10, the surge frequency component is not
, And flows to the ground terminal, so that the element can be protected from surge voltage. Alternatively, as shown in FIG. 8, a diode 5 and an inductance 32 are connected in series between the input terminal 1 and the ground terminal, and a diode 51 and an inductance 5 are connected between the output terminal 2 and the ground terminal.
2 may be connected in series. By providing the protection circuits on the input side and the output side in this way, it is possible to more reliably remove the surge component.

Further, the protection circuit according to the first embodiment and the modification thereof includes a GaAs MESF as an element.
It is provided on the input side and / or output side of ET10.
However, the protection circuit of the present invention employs a Si high-frequency MOSFET.
It may be provided on the input side and / or the output side of all elements for processing high frequency signals such as T, Si high frequency bipolar transistor, high frequency junction FET, HEMT, HBT, HET and the like. Furthermore, not only a PN junction diode, but also an NPN junction diode, a PIN diode, or the like may be used as the capacitance, and the inductance is not limited to a spiral inductance, and may be a meander line, a high impedance line, or the like.

Further, in the circuit shown in FIG. 1, FIG. 7 or FIG. 8, the diode 5 and the inductance 32 are connected in series between the input terminal 1 and / or the output terminal 2 as described above. However, the inductance 32 has a resistance component. Therefore, the diode 5, the inductance 32
Alternatively, a configuration may be adopted in which a parasitic resistance or a new resistance is connected in series. When this resistor is added, the resonance waveform shown in FIG. 3 becomes wider, and it becomes easy to include a surge frequency component.

FIG. 9 shows a configuration in which the protection circuit according to the second embodiment of the present invention is applied to an RF circuit 62.
On the input side of the RF circuit 62, a capacitance 64 and an inductance 65 are connected in parallel between the input terminal 61 and the ground terminal, and a node connecting one end of the capacitance 64 and the inductance 65 is connected to the input terminal of the RF circuit 62. The capacitor 66 is connected between them. Incidentally, the capacitance 66 is a cut capacitance. Here, since the inductance 65 includes a resistance component, a configuration in which a parasitic resistance is added in series between one end of the capacitance 64 and the inductance 65 and the input terminal 61 may be taken into consideration, or a new configuration may be adopted. And a configuration in which a resistor is added in series. The first
In the embodiment, the protection circuit is configured as an LC or LCR series bandpass filter, but in the second embodiment, the protection circuit is configured as an LC or LCR parallel anti-resonance circuit.

FIG. 10 shows the frequency dependence of the conductance G of the protection circuit according to the second embodiment. The capacitance C and the inductance L are set so that the RF frequency of the signal input from the input terminal 61 and the resonance frequency f0 of the protection circuit having the capacitances 64 and 66 and the inductance 65 substantially coincide with each other. Adjust the width by setting the resistance value to pass the component. Thus, as in the first embodiment, the protection circuit can supply the RF circuit 62 without passing the high frequency component, and can pass the surge frequency component to the ground terminal.

Here, as shown in FIG. 11, the capacitor 66 may be removed from the protection circuit in the second embodiment. Further, the capacitance 71 and the inductance 72
Or an LCR parallel anti-resonance circuit having a resistance component added thereto may be provided between the output terminal 63 and the ground terminal as shown in FIG. Alternatively, such an LC or LCR parallel anti-resonance circuit may be provided between the input terminal 61 and the ground terminal and between the output terminal 63 and the ground terminal. As the capacitance, any capacitance such as a coupling capacitor and an MIM capacitor can be used. FIG. 13 shows a configuration in which the protection circuit according to the third embodiment of the present invention is provided on the input side of the RF circuit 62. This protection circuit is composed of a CR high-pass filter including a capacitor 71 and a resistor 72. And
As shown in FIG. 14, the cutoff frequency fc is set between the RF frequency of the high frequency signal and the surge frequency, for example, 1 GHz.
Set to z. Thereby, of the signals input from the input terminal 61, the high-frequency signal is input to the RF circuit 62 without passing from the protection circuit to the ground terminal, and the surge frequency component flows to the ground terminal through the protection circuit.

In the third embodiment, the protection circuit is provided on the input side. However, as shown in FIG. 15, a protection circuit including a capacitor 81 and a resistor 82 is provided between the output terminal 63 and the ground terminal. Or may be provided on the input side and the output side.

FIG. 16 shows a configuration of a protection circuit according to a fourth embodiment of the present invention. In this embodiment, a protection circuit is provided as a C-CL type band-pass filter in which a capacitance 91, a capacitance 92 and an inductance 93 are connected in parallel between an input terminal 61 and a ground terminal. It is configured. The frequency dependence of the conductance of the protection circuit in this case is as shown in FIG. By setting the cutoff frequency fc near the RF frequency of the high-frequency signal and including the surge frequency region, the high-frequency signal is given to the RF circuit 62 without passing through the protection circuit, and the surge frequency component is transmitted from the protection circuit. Flows to ground terminal. In the fourth embodiment, the C-CL bandpass filter is provided on the input side, but may be provided on the output side, or on the input side and the output side.

[0025]

As described above, the protection circuit of the present invention is applied to the element without passing a high-frequency signal, and the surge frequency component is passed to the ground terminal without being applied to the element, thereby affecting the characteristics of the element. Can be protected without giving.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing an element structure of the bias circuit.

FIG. 3 is a graph showing frequency dependence of conductance in the protection circuit.

FIG. 4 is a graph comparing the surge tolerance of the protection circuit and the conventional bias circuit shown in FIGS. 18 and 20;

FIG. 5 is a graph comparing noise factors of the protection circuit and the conventional bias circuits shown in FIGS. 18 and 20;

FIG. 6 is a graph comparing high-frequency gains of the protection circuit and the conventional bias circuits shown in FIGS. 18 and 20;

FIG. 7 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to a modified example of the first embodiment.

FIG. 8 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to another modification of the first embodiment.

FIG. 9 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to a second embodiment of the present invention.

FIG. 10 is a graph showing frequency dependence of conductance in the protection circuit.

FIG. 11 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to a modification of the second embodiment.

FIG. 12 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to another modification of the second embodiment.

FIG. 13 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to a third embodiment of the present invention.

FIG. 14 is a graph showing frequency dependence of conductance in the protection circuit.

FIG. 15 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to a modified example of the third embodiment.

FIG. 16 is a circuit diagram showing a configuration of a bias circuit using a protection circuit according to a fourth embodiment of the present invention.

FIG. 17 is a graph showing frequency dependence of conductance in the protection circuit.

FIG. 18 is a circuit diagram showing a configuration of a conventional bias circuit that does not use a protection circuit.

FIG. 19 is a longitudinal sectional view showing the element structure of the bias circuit.

FIG. 20 is a circuit diagram showing a configuration of a conventional bias circuit using a conventional protection circuit.

FIG. 21 is a longitudinal sectional view showing an element structure of the bias circuit.

[Explanation of symbols]

1, 61 input terminal 2, 63 output terminal 3, 4 bias power supply 5 diode 32, 52, 65, 72, 93 inductance 11 GaAs substrate 12 gate metal 13 drain electrode 14 gate electrode 15 source electrode 16 n ⁺ type impurity region (drain) Region) 17 channel region 18 n ⁺ type impurity region (source region) 21 diode p ⁺ type impurity region 22 diode n ⁺ type impurity region 23, 24, 41, 43 wiring 42 spiral inductance 62 RF circuit 64, 66, 71, 81 , 91, 92 Capacity 82 Resistance

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H03F 1/52

Claims (6)

[Claims] 1. A protection circuit connected between an input terminal of a circuit for processing a high-frequency signal and a ground terminal, wherein the protection circuit converts a high-frequency signal component of a signal input from the input terminal. A protection circuit, wherein the circuit passes through the circuit, does not pass through the ground terminal, and passes a surge frequency component to the ground terminal without passing through the circuit. 2. A protection circuit connected between an output terminal of a circuit for processing a high-frequency signal and a ground terminal, wherein the protection circuit is one of signals output from the circuit.
A protection circuit, wherein a high-frequency signal component passes through the output terminal and does not pass through the ground terminal, and a surge frequency component passes through the ground terminal without passing through the output terminal. 3. The protection circuit according to claim 1, wherein a capacitance and an inductance are connected in series between the input terminal and the ground terminal, or the output terminal and the ground terminal, or the capacitance, the inductance and the resistance are connected in series. The protection circuit according to claim 1, wherein the protection circuit is connected to a terminal. 4. The protection circuit according to claim 1, wherein a capacitance and an inductance are connected in parallel, or an inductance and a resistance are connected in series, between the input terminal and the ground terminal or between the output terminal and the ground terminal. 3. The protection circuit according to claim 1, wherein the output and the capacitor are connected in parallel. 5. The protection circuit according to claim 1, wherein a high-pass filter including a capacitor and a resistor is provided between the input terminal and the ground terminal or between the output terminal and the ground terminal. 3. The protection circuit according to 1 or 2. 6. The protection circuit according to claim 1, wherein a capacitance and an inductance are connected in parallel between the input terminal and the ground terminal or between the output terminal and the ground terminal, and the capacitance is connected in series. The protection circuit according to claim 1, wherein the protection circuit is provided.