JPH0362022B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a semiconductor device, and more particularly to a semiconductor device provided with a malfunction prevention means to prevent malfunction even when a steep motion is input.

[Prior art]

Conventionally, in a semiconductor device (semiconductor integrated circuit), the inductance of an input terminal, the inductance of a power supply terminal, and the input wiring capacitance may start to resonate due to the movement of an input signal, causing malfunction of the semiconductor device. This will be explained using drawings.

FIG. 1 is a diagram for explaining the impedance of an example of a conventional semiconductor device.

In FIG. 1, 1 is the semiconductor device board, 2 is the internal circuit of the ECL differential input type other than the input wiring capacitance,
L _VCC and L _VEE are the inductance of the power supply terminal (case and bonding wire), C ₁ ~ Ci ~ Cm and C ₁ ′ ~
Ci′ to Cm′ are input wiring capacitances, and L _I1 to L _Ii to L _In are parasitic inductances that exist from the input terminal T _IN of the semiconductor device to the input nodes a ₁ to a _n in the semiconductor substrate 1, respectively. .

FIG. 2 is an AC equivalent circuit diagram of FIG. 1.

In Fig. 2, the inductance L _P is the parallel inductance of L _VCC and L _VEE in Fig. 1, and the capacitance C _Al is the parallel capacitance of all the input wiring capacitances C ₁ to Ci to Cm and C ₁ ′ to Ci′ to Cm′. The inductance L _I is L _I1 ~ _{L Ii} ~
It is the parallel inductance of L _In .

Here, L _VCC = L _VEE L _I1 =...=L _Ii =...L _In C ₁ =...=Ci=...Cm C ₁ '=...=Ci'=...=Cm'. Also, the high potential side power supply terminal of internal circuit 2
The connection between V _C and the low-potential side power supply terminal V _E has a very low impedance determined by the internal circuit, so it is in a short state in terms of AC, so it is the same as reference node b in internal circuit 2. It can be assumed to be the electric potential.

The voltage level of the input terminal T _IN of the semiconductor device becomes a fixed level after the input transitions. Considering the case when the voltage level of the input terminal changes suddenly, this equivalent circuit starts to resonate in series due to the stored electromagnetic energy and electrostatic energy, and point a on the input terminal side and point b on the power supply terminal side are as follows. The voltage induced in the inductance and the voltage induced in the capacitance move in opposite phases. In other words, after the voltage level of the input terminal reaches a fixed level, the alternating current flowing through this equivalent circuit is Im
If sinωt, the voltage induced in the capacitance is 1/ωC _Al Im sin (ωt−π/2), and the voltage induced in the inductance is ωL _P Im sin (ωt+π/2) and ωL _I Im sin (ωt+π/2 ), resulting in a phase shift of π from the voltage induced in the capacitor.

As a result, a of the AC equivalent circuit shown in FIG.
At points B and B, resonance waveforms whose phases are shifted by π are superimposed on the DC voltage. Here, in terms of AC, the power terminal
Since the voltages of the power supply terminals V _C and V _E connected from T _P through the inductance L _p move in the same phase, the AC level of the internal circuit 2, that is, the reference node b
All of them operate in the same phase as the voltage at terminals V _C and V _E. As a result, the input nodes a 1 _{to 1} of the semiconductor substrate 1 shown in FIG.
The voltage at a _n and the reference voltage generated by the internal circuit 2 are in opposite phase.

FIG. 3 is a waveform diagram of voltages appearing at each point on the input terminal side and power supply terminal side in the conventional product and the present invention.

In Fig. 3, voltage waveforms a and b correspond to nodes a and b in Fig. 2.
On the other hand, V _IN is an input voltage level input to the ECL differential input type internal circuit 2 that changes between -1.6V and -0.8V, and V _ref indicates a reference voltage of -1.2V. As shown in Figure 3, the input voltage level
V _IN crosses the reference voltage V _ref . Because of this intersection, when there is a sudden movement _in the input voltage level V Also, series resonance voltages shown in voltage waveforms a and b are generated at the reference node b, respectively, and the circuit malfunctions.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device which eliminates the above drawbacks and prevents malfunction due to series resonance when there is a sudden movement of the input.

[Structure of the invention]

The semiconductor device of the present invention receives an input voltage that rapidly changes between high and low levels with respect to a reference voltage of an ECL differential input type internal circuit provided in a semiconductor substrate from an input terminal for external connection. In the semiconductor device that inputs the input to the internal circuit through the input node in the semiconductor substrate, a shot barrier diode connected in anti-parallel or a shot barrier diode connected in anti-parallel is connected between the reference voltage node and the input node. It is configured by providing a series circuit of a diode and a capacitive element.

[Explanation of Examples]

Next, embodiments of the present invention will be described using the drawings.

FIG. 4 is an equivalent circuit diagram of an embodiment of the first invention.

In this embodiment, an input voltage level that changes between high and low levels in several ns with respect to the reference voltage V _ref of an ECL differential input type internal circuit 2 of a semiconductor substrate 1 is shown.
This is a semiconductor device that inputs V _IN from an input terminal T _IN for external connection to an internal circuit 2 via an input node a in a semiconductor substrate 1, and a reference voltage terminal.
An anti-parallel circuit of shot barrier diodes D ₁ and D ₂ is inserted between T _vref and input node a.

FIG. 4 shows the AC equivalent circuit of this embodiment, and the actual circuit _{corresponding} to FIG. ₁ of the conventional example has diodes D ₁ , Provide an anti-parallel circuit of D ₂ .

The input voltage level V _IN of the input terminal T _IN of the semiconductor device shown in Fig. 4 has a steep transition of several ns, and the input node
The AC potential difference between a′ and the reference voltage terminal T _vref is 1/ωC _Al Im sin (ωt−π/2) =−1/ωC _Al Im cosωt as described above. At this time |-1/ωC _Al Im cosωt±DCoffset|≧Vf _SBD (Here, DCoffset = DC bias between the input terminal and reference voltage terminal) (Vf _SBD = Forward voltage of the shot barrier diode, usually about 0.4V) If so, the clamp is applied, and the energy stored in the resonant circuit is consumed within the shot barrier diode, and the resonance level is significantly reduced, providing a large operating margin against malfunctions.

As shown in voltage waveforms a' and b' in Figure 3, after the input voltage level V _IN rises with a steep waveform of several _nanoseconds , the short barrier diode is Clamping is applied at −0.8V, which is 0.4V higher than the directional voltage V _fSBD , and energy is consumed to suppress subsequent series resonance phenomena. Moreover, this forward voltage V _fSBD is 0.4V
Since it is half of the input DC potential difference of 0.8V,
There is no adverse effect such as input voltage distortion due to the insertion of the diodes D ₁ and D ₂ .

FIG. 5 is an equivalent circuit diagram of an embodiment of the second invention.

This embodiment includes an internal circuit 2 and an internal circuit 2.
A capacitive element whose one electrode is connected to the input terminal T _{IN of}
The anode is connected to C _CL and the other electrode of this capacitive element, and the reference voltage terminal T _Vref of internal circuit 2 is connected to C CL and the other electrode of this capacitive element.
a first diode D ₁ whose cathode is connected to;
The semiconductor substrate includes a second diode _D2 whose cathode is connected to the other electrode of the capacitive element _CCL and whose anode is connected to the reference voltage terminal T _Vref . That is, diodes D ₁ , D ₂ and capacitive element
Configure a clamp circuit with C and _CL . In addition, shot barrier diodes are used for the diodes D ₁ and D ₂ . The capacitive element C _CL cuts off the DC current path, cuts off the DC current of the short barrier diode when the input DC potential difference is larger than V _fSBD , reduces the load effect on the input terminal, and clamps only the AC component transiently. ing.

〔Effect of the invention〕

As explained in detail above, according to the present invention,
A semiconductor device can be obtained that can prevent malfunction even if there is a steep movement in the input.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the impedance of an example of a conventional semiconductor device, FIG. 2 is an equivalent circuit diagram of FIG. FIG. 4 is an equivalent circuit diagram of an embodiment of the first invention, and FIG. 5 is an equivalent circuit diagram of an embodiment of the second invention. 1...Semiconductor substrate, 2...Internal circuit, C, C ₁
~Cm, C′ ₁ ~C′m, C _Al ... Input wiring capacitance, C _CL ...
... Capacitive element, D ₁ , D ₂ ... Diode, L ₁ , L _I1 ~
L _In ... Inductance of input terminal, L _P , L _VCC ,
L _VEE ...Inductance of power supply terminal, T _IN ...Input terminal, T _P ...Power supply terminal, T _Vref ...Reference voltage terminal, V _C ...High potential side power supply terminal, V _E ......
Low potential side power supply terminal, V _IN ……Input voltage level,
V _ref ...Reference voltage, a, a'...Input node, b...Reference node.

Claims (1)

[Claims] 1. An input voltage that rapidly transitions between high and low levels with respect to the reference voltage of an ECL differential input type internal circuit provided in a semiconductor substrate is input from an input terminal for external connection. In the semiconductor device that inputs input to the internal circuit via an input node in the semiconductor substrate, a shot barrier diode connected in antiparallel is provided between the reference voltage node and the input node. Semiconductor equipment. 2 An input voltage that rapidly transitions between high and low levels with respect to the reference voltage of an ECL differential input type internal circuit provided in a semiconductor substrate is input from an input terminal for external connection into the semiconductor substrate. The semiconductor device inputs input to the internal circuit through a node, characterized in that a series circuit of a shot barrier diode and a capacitive element connected in antiparallel is provided between the reference voltage node and the input node. semiconductor devices.