JPH03212018A - Driver circuit with i/o switch - Google Patents

Abstract

PURPOSE:To decrease the number of current sources in comparison with that of a conventional circuit by integrating a driver circuit and an I/O switch cir cuit. CONSTITUTION:A driver circuit driving a load at a prescribed voltage level and an I/O switch circuit separating the driver from a DUT at its input are integrated. Then the level of an input output mode switching signal I/O is in creased more than an output voltage switching signal H/L, and the output voltage switching signal H/L is fed in-phase to a 3rd TR 3B, a 6th TR 3E, a 5th TR 3C and a 5th TR 3F respectively, and fed in opposite phase between the 3rd TR 3B and the 6th TR 3E and between the 5th TR 3C and the 5th TR 3F. Thus, the number of current sources is decreased.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention integrates a driver circuit that drives a load at a predetermined voltage level and an I/O switch circuit that disconnects the driver circuit from a DUT at the time of input. This is about a circuit that has been converted into a circuit.

[Prior Art] Next, the configurations of a driver circuit and an I/O switch circuit according to the prior art will be explained with reference to FIG.

The reference source 11 in FIG. 2, transistors 12A and 12B,
The resistor 13 and current source 14A constitute a driver circuit, and the current sources 14B and 14C, transistors 15A to 15D, diode bridge 16, and load resistor 17 constitute an I/O switch circuit.

The reference power supply 11 is V when "I". 1. When rLJ, V
In order to apply OL to the load resistor 17, it is set to 2·volI.

The current source 14A supplies a current of 2·(VOHVOL/Ro) to the load resistor 17 under the control of the differential transistor pair 12A and 12B.

The resistor 13 is a resistor that determines the output impedance of the driver circuit, and has a resistance value of RO.

16 is a diode bridge, and current sources 14B and 14G supply current to the diode bridge 16. flowing,
Transistors 15A-15D are transistor switches that switch the current flowing through the diode bridge.

The resistance value of the load resistor 17 is assumed to be RL.

Next, the time chart of FIG. 2 will be explained with reference to FIG. 4.

FIG. 4A is a waveform diagram of the input/output mode switching signal I/O, which is applied as a differential signal to the bases of transistors 15A to 15D.

Therefore, transistors 15A and 15B, 15G and 1
5D serves as a differential switch and controls the currents of current sources 14B and 14C.

FIG. 4A is a collector current waveform diagram when the transistors 15A and 15G are on. Transistor 15A・1
When 5C is turned on, the currents of the current sources 14B and 14G do not flow through the diode bridge 16, the diode switch 16 is turned off, and the 8-power terminal becomes a high impedance state in mode ■.

FIG. 4 is a collector current waveform diagram when the transistors 15B and 15D are on, the diode bridge 16 is on, and the output terminal is in O mode and connected to the driver circuit.

Figure 4 is a waveform diagram of the output voltage switching signal H/L,
It is applied as a differential signal to the bases of transistors 12A and 12B.

Therefore, transistors 12A and 12B act as differential switches and switch the current of current source 14A.

Figure 4 shows a waveform diagram of the transistor 12B. When the transistor 12B is off, the output terminal is not affected by the current source 14A, so when the I/O switch section is in the O mode, the output voltage is ■. is 2・VOI(・Rt / (Ro
+ Ri, ).

The fourth diagram shows the output voltage V. When the transistor 12I3 is on, all the current [14A drawn in] flows through the transistor 12B, so when the I/O switch section is in O mode, the output voltage V. is 2 ・Vat,
-Rt, / (Ro + RL).

Note that since RO is normally set to RL, the output voltage is ■.

are each V. It becomes H and VOL.

Furthermore, the waveform shown by the dotted line in the fourth diagram indicates that the diode switch 16 is turned off and the output terminal is in the high impedance state of mode ■.

[Problem to be solved by the invention] The conventional circuit shown in FIG. 2 uses three current sources, but the I
In order to increase the speed and reduce the size of C testers and the like, there is a demand for high-density packaging of circuits and reduction of power consumption.

An object of the present invention is to provide a circuit in which the number of current sources is reduced by integrating a driver circuit and an I/O switch circuit.

[Means for Solving the Problem] In order to achieve this object, in the present invention, when the output voltage is "11", V. 11. When the output voltage is “L”, VO
When the resistance value of the reference power supply 1 where the voltage (V on + V oi,) is set with respect to L and the resistance value of the load resistor 6 is RO,
A first current source 2A and a second current source 2B that supply the current (VORVat, )/Ro are connected between the first current source 2A and the reference power source 1, and the input/output mode switching signal I/O
, a second transistor 3D connected between the reference power supply 1 and the second current source 2B and supplied with the input/output mode switching signal I/O;
a third transistor 3B connected to the current source 2A and the reference power source 1 and supplied with the output voltage switching signal H/L;
A fourth transistor 3 connected between the reference power source 1 and the second current source 2B and supplied with the output voltage switching signal H/L.
E, and a fifth current source connected between the first current source 2A and the diode bridge 4 and supplied with the output voltage switching signal H/L.
transistor 3C, diode bridge 4 and second
is connected between the current source 2B of the output voltage switching signal H/L.
and a resistor 5 connected between the reference power supply 1 and the diode bridge 4, the amplitude of the input/output mode switching signal I/O is determined from the output voltage switching signal H/L. is also increased, and the output voltage switching signal H/L is set to the third transistor 3B, the sixth transistor 3E,
The fifth transistor 3C and the fifth transistor 3F are supplied with the same phase, and the third transistor 3B and the sixth transistor 3E, and the fifth transistor 3C and the fifth transistor 3F are supplied with the opposite phase. .

Next, the configuration of a driver circuit with an I/O switch according to the present invention will be explained with reference to FIG.

1 in Figure 1 is a reference power supply, 2A and 2B are current sources, 38-3
F is a transistor, 4 is a diode bridge, 5 is a resistor connected between the reference voltage [1] and the diode bridge 4, and 6 is a load resistance.

V when the output voltage is "H". II. When the output voltage is "L", the voltage (V OH + V, ot,) is set to the reference power supply 1 with respect to VOL, and the currents of the current sources 2A and 2B are (
VaHVOL)/RO.

Transistors 3A to 3C13D to 3F constitute two common emitter differential switches, and 3B, 3C13E, and 3F
An output voltage switching signal H/L is applied to each base. This signal is supplied to the transistors 3B and 3E and the transistors 3C and 3F in the same phase, and is supplied in the opposite phase between the transistors 3B and 3E and the transistors 3C and 3F.

Furthermore, input/output mode switching signals I/O having mutually opposite phases are applied to the bases of the transistors 3A and 3D.

Note that the amplitude of the input/output mode switching signal ■/○ is made larger than the output voltage switching signal H/L.

The diode bridge 4, resistor 5, and load resistor 6 have the same configuration as the diode bridge 16, resistor 13, and load resistor 17 shown in FIG.

[Operation] Next, the time chart of FIG. 1 will be explained with reference to FIG. 3.

FIG. 3A is a waveform diagram of the input/output mode switching signal I/O.

FIG. 3A is a collector current waveform diagram of the transistor 3A, and FIG. 3 is a collector current waveform diagram of the transistor 3D. The collector current of transistors 3A and 3D in the ■ mode is (V.)I-VOL)/RO.

Figure 3 is a waveform diagram of the output voltage switching signal H/L.

Figure 3 is a collector current waveform diagram of transistor 3C, and Figure 3 is a collector current waveform diagram of transistor 3F.6 The collector currents of transistors 3C and 3F are:
(V on Vat) / becomes Ro.

Figure 3 K is the output voltage V. FIG.

The amplitude of the input/output mode switching signal I/O in Figure 3A is
Since it is larger than the amplitude of the output voltage switching signal H/L of the craft,
When transistors 3A and 3D are on, current sources 2 and 2
All current of B flows through transistors 3A and 3D, and transistors 3B, 3C, 3E, and 3F are turned off.

Therefore, the diode bridge 4 is also turned off, and the output terminal becomes a high impedance state as shown by the dotted line in FIG. 3G.

When transistors 3A and 3D are off, transistor 3
B, 3C, 3E, and 3F are turned on and off using the output voltage switching signal H.
/L.

If the transistors 3B and 3F are on, the current from the current source 2A flows from the transistor 3B to the reference power supply 1 and does not flow to the load resistor 6.

All the current drawn by the current source 2B is supplied from the transistor 3F to the resistor 5 and the load resistor 6, and the output voltage Vo is
2・RL/(RO+RL)・Vat.

When the transistors 3C and 3E are on, the current of the current source 2A is shunted from the transistor 3C to the resistor 5 and the load resistor 6.

The current drawn by the current source 2B is supplied from the reference power supply 1 via the transistor 3E, and does not flow through the load resistor 6.

Output voltage at this time■. teeth, 2・RL　/　(RO+RL　)　・Voo.

Note that normally, Ro=RL is set for output matching, so the output voltage is vol, "L" when r I-I J.
When ■. , becomes.

[Effects of the Invention] According to the present invention, since the driver circuit and the I/O switch circuit are integrated, the number of current sources can be reduced compared to the conventional circuit.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a driver circuit with an I/O switch according to the present invention, Fig. 2 is a block diagram of a driver circuit and a switch circuit according to the prior art, Fig. 3 is a time chart of Fig. 1, and Fig. 4 is a block diagram of a driver circuit with an I/O switch according to the invention. The figure is a time chart of FIG. 2. 1...Reference power supply, 2A...Current source, 2
B...Current source, 3A to 3F...Transistor, 4...Diode bridge, 5...
...Resistance, 6...Load resistance.

Claims (1)

[Claims] 1. When the output voltage is "H", V_O_H, the output voltage is "
When the voltage is V_O_L, the voltage (V_O_H+V_
When the resistance value of the reference power supply (1) where O_L) is set and the resistance value of the load resistor (6) is R_O, the current (V_O
A first current source ( _H−V_O_L)/R_O that supplies
2A) and a second current source (2B); and a first transistor (2A) connected between the first current source (2A) and the reference power supply (1) and supplied with an input/output mode switching signal I/O. 3A), a second transistor (3D) connected between the reference power supply (1) and the second current source (2B) and supplied with the input/output mode switching signal I/O, and the first current source. A third transistor (3B) is connected between the reference power source (2A) and the reference power source (1) and is supplied with the output voltage switching signal H/L; A fourth transistor (3E) is connected between the first current source (2A) and the diode bridge (4) and is supplied with the output voltage switching signal H/L. A fifth transistor (3C) is supplied with H/L, and a sixth transistor is connected between the diode bridge (4) and the second current source (2B) and is supplied with an output voltage switching signal H/L. transistor (3F) and a resistor (5) connected between the reference power supply (1) and the diode bridge (4), and converts the amplitude of the input/output mode switching signal I/O into the output voltage switching signal H/ The output voltage switching signal H/L is in phase with the third transistor (3B) and the sixth transistor (3E), and the fifth transistor (3C) and the fifth transistor (3F), respectively. and the third transistor (3
A driver circuit with an I/O switch characterized in that supplies are supplied in reverse phase between B) and the sixth transistor (3E), and between the fifth transistor (3C) and the fifth transistor (3F).