JPS6161521A - Electric field drive type pnpn switch circuit - Google Patents

Abstract

PURPOSE:To prevent current leakage to a load from a drive circuit by using either of an anode or a cathode terminal of a PNPN switch as a source terminal of a field effect transistor (TR) to drive the field effect TR. CONSTITUTION:SWP, SWN are closed at on-operation and voltage sources VP, VN are applied respectively to gates GP, GN of PMOS MP and NMOS MN. When the anode potential VA of the PNPN switch is higher than the VP, the MP is turned on, the QN is driven and the PNPN switch is triggered. When the cathode potential VK is lower than the VN conversely, the MN is turned on, the QP is driven and the PNPN switch is triggered. Thus, it is not always required for the VP, VN to give them a larger absolute value than the voltage amplitude of the signal at load side. Further, since the PNPN switch is triggered by voltage drive, no current leakage to the load from the drive circuit exists.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an electric field driven PNPN switch circuit, and particularly to a switch circuit suitable for a circuit in which driving rMJt current is a problem.

[Background of the invention]

Conventionally, PNPN switches and the like have been widely used for converting electromagnetic parts such as relays into semiconductors because of their ease of driving. P for spear 1
NPN switch 1 and constant current source IGK that turns it on
, indicates IOA. GA and GK represent inputs from constant current sources IGK and Ic, respectively. FIG. 2 is an equivalent circuit diagram of the device shown in FIG. 1, where QP and QK are PNP and NPN transistors, respectively. The device shown in FIG. 1 can turn on the anode (A) of the PNPN switch without depending on the potential or the cathode (K) potential, but when trying to supply a counter current to the load side, It is necessary to connect the circuits shown in the figure in antiparallel to constantly drive the constant current source IGK and IC. Otherwise, the PNi'N switch turns off during current reversal. Therefore, there is a problem in that the drive current flows into the load side, and it cannot be applied to circuits where this current is a problem.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide an electronic switch circuit suitable for semiconductor integration that does not cause current leakage from the drive circuit to the load side.

[Summary of the invention]

In order to achieve the above object, an electric field driven type P according to the present invention
The NPN switch circuit includes an equivalent PNPN switch consisting of a pair of mutually complementary transistors whose collectors are connected to the other pace, and transistors connected in parallel to the pair of complementary transistors. a pair of complementary field effect transistors of the same conductivity type;
The field effect transistor is configured by a drive circuit that controls on/off the field effect transistor, and the field effect transistor is driven by using the anode or cathode terminal of the PNPN switch as the source terminal of the field effect transistor. The gist is that the switch is controlled on-off.

That is, in the present invention, by combining a PNPN switch and a field effect transistor to form an electric field drive type switch circuit, it is possible to perform on-off control without leakage current from the drive circuit flowing to the load side. This was done based on the knowledge of the inventors of the present invention.In order to enable switching operation of a signal higher than the power supply voltage of the drive circuit, the PNJ'N switch circuit according to the present invention has the following characteristics:
A pair of complementary field effect transistors are voltage driven 5 with their respective sources being the anodes or cathodes of the PNPN switches.

The present invention will be described in more detail below using examples with reference to one drawing, but these are merely illustrative and it is understood that various modifications and improvements may be made without going beyond the scope of the present invention. It's obvious.

[Embodiments of the invention]

Figure 3 is a circuit diagram of the first embodiment showing the basic circuit configuration of the present invention, and Figure 4 is its equivalent circuit diagram. 1 is PNPN
The switch, 2 is a gate electrode provided on the N base 4 of the PNPN switch, the gate electrode (Gp) of PMO8 (Mp) in FIG. 4, 3 is the electrode provided on the P pace 5 of the PNPN switch 1, There is a resounding effect on the gate electrode (GN) of NMO8 (MN) in Figure 4. QP is the PNP transistor part of the l'Ni'N switch 1, and QN is the NPN transistor part. Vp is a voltage source for PMO8 (Mp)Jln operation, and δWp is a switch for ON control. V
N is a voltage source for driving NMO8 (MN), and SWN
is a switch for on control. Although SWP and SWN are shown as contacts, they are actually configured electronically using transistors. The circuit shown in Figure 4 operates as follows. For on operation, close SWP and SWN and use voltage sources Vp and VN.
'i (;i'L PMO8 (Mp), NMO8 (Mp)
N) gates Gp and GN.

When the anode potential MA of the PNPN switch is higher than Vp, PM(JS (Mp) is turned on and QN is driven, causing the PNPN switch to fire. Conversely, when the cathode potential VK is lower than VN, NMO8( MN) turns on and QP is driven, which causes the PNPN switch to fire.

That is, the two MOS transistors Mp and MN are turned on using the anode terminal A and the cathode terminal K as sources, respectively. Therefore, two driving voltage sources V-P
, it is not necessary for VN to be a power supply whose absolute value is larger than the voltage amplitude of the signal on the load side (this will cause significant damage to the drive circuit. For example, it is possible to turn on the voltage at Vp-0 and VN-□V). .

Furthermore, since the PNPN switch is fired by voltage drive, there is no current leakage from the drive circuit to the negative 4rfr side, so an ideal switch can be realized. The off operation is performed by two switches S~'vp.

When SWN is opened, the voltage drive to the two MO8Mp and MN is stopped, so MP and MN are turned off.

Since the PNPN switch has a self-holding function, the PNPN switch turns off when the current flows to 0, and since the on-drive stops after this, it maintains the off state even if the signal voltage is applied. Continue.

Figure 5 is an equivalent circuit diagram of the embodiment of Figure 2 showing a specific circuit configuration of the present invention, in which parts common to those in Figure 4 are given the same symbols. Ml is NMO8 and corresponds to switch 8Wp in Fig. 4.

M2 is PMQ8, which corresponds to SWN of 4 swords.

■1 is the power supply for driving NMO3 (Ml), and SWl
is applied by (2) is a power supply for driving PMQ8 (M2), and is applied by SW. Dl and Dl are diodes for blocking reverse voltage application of NMO8 (Ml) and PMQ:03 (M2), respectively. PGp and RGN are each PMC)8 (~IP).

This is a high resistance for fixing the gate potential of NMO8 (MN).

The basic movement is the same as the 4th figure.

During ON operation, NMO8 (Ml), PMQ8 (M2)
Since both are in the on state, the gates of PMQ8 (1.Mp) and NMO8 (MN) are at ground potential.

When the anode (A) of the PNl'N switch is at a positive potential, PMQ8 (Mp) is turned on, causing the PNPN switch to fire, and when the cathode (K) is at a negative potential, the NMO8
(Mp) turns on, the PNPN switch fires.

The resistors RGP and RGN are extremely thick for fixing the gate potential (as it is possible to do so, the current leaking from the drive circuit to the load side when the PNPN switch is turned on can be extremely small, making it difficult for practical use. There is no problem. The diodes D1 and Dl can be omitted depending on the signal amplitude voltage on the load side.

FIG. 6 is an equivalent circuit diagram showing another specific circuit configuration of the present invention. NMO8 (Ml) for driving spear 5
Use an NPN transistor Q14 instead of Q14, change it to ON drive with a current source, and use it for driving (Figure 5)
Using PNP) transistor Q2 instead of O8 (M2),
This was modified to be turned on with a current source. Since it is turned on using a transistor, highly sensitive turn-on control is possible.

FIG. 7 is an equivalent circuit diagram of a square inch circuit according to a fourth embodiment of the present invention, which has been improved to prevent erroneous firing of a PNPN switch in the OFF state. Resistor RGK is P
It is connected between the pace and emitter of the NPN switch that constitutes the NPN switch, and has the effect of preventing erroneous firing due to leakage current flowing through the PN junction. Volume 1c
cp.

CG N are PMQ8 (MP) and NMO8 (
+Ij is connected between the gate and source of MN), and from the application of a voltage with a steep rise t, i' MU 8 (tvl p
) NMO8 (MN) is driven through the capacitor tv on the drive circuit side, which has the effect of preventing the PNPN switch from erroneously firing.

FIG. 8 is a cross-sectional view of the circuit shown in FIG. 6 when it is made into a semiconductor integrated circuit, excluding the drive circuit (oxidized into polycrystalline silicon 7 using well-known dielectric isolation technology). An 'NPN structure is created in the N-type single crystal island 4. )'The gate electrode Gp of MO8 (MP) is N pace 4
An oxide film 6 is formed thereon. The gate electrode GN of NMO3 (MN) is formed on the P base 5 with an oxide film 6 interposed therebetween. Resistors RGP and RGN can be made of polycrystalline silicon formed on an oxide film. In this way, the PNk# switch circuit according to the present invention can be easily integrated into a semiconductor.

〔Effect of the invention〕

As explained above, according to the present invention, 1. there is no current leakage from the drive circuit to the load side; An electric field driven NPN switch circuit suitable for semiconductor integration can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional PNPN switch circuit, FIG. 2 is an equivalent circuit diagram of the circuit shown in FIG. 1, FIG. 5 is a circuit diagram showing the basic circuit charging of the present invention, and FIG. 5 to 7 are equivalent circuit diagrams of the PNPN switch circuit according to three different embodiments of the present invention, and FIG. 8 is an equivalent circuit diagram of the circuit shown in FIG. Excluding the drive circuit when integrated (this is a cross-sectional view. 1...PNPN switch, 2.3... Gate electrode,
4...N pace, 5...P pace, 6.8...Oxide film, 7...Polycrystalline silicon, A...Anode, K
...Cathode, Dl, 1)2...Diode, QP
, Q2...PNP) transistor, QN, Ql...
N)'N) Transistor, MP, M2...PM (JSl
MN, Ml...NMO8 Closed 10 Mo20 Tsumugi 3rd Tsumugi 40th 5th illusion 62nd 70th 80th

Claims (1)

[Claims] An equivalent PNPN switch consisting of a pair of mutually complementary transistors whose collectors are connected to the base of the other, and transistors of the same conductivity type as the transistors, each connected in parallel to the pair of complementary transistors. The PNP is composed of a pair of complementary field effect transistors and a drive circuit that controls on/off the field effect transistors.
By driving the field effect transistor by using either the anode terminal or the cathode terminal of the N switch as the source terminal of the field effect transistor, the PNPN
An electric field-driven PNPN switch circuit characterized in that a switch is controlled on-off.