JPH024013A - Semiconductor device - Google Patents

Abstract

PURPOSE:To always make two constant currents into the same value by comparing the current of the constant current source of a bipolar transistor for detecting and the current of the constant current source of a MOS transistor through the use of a load and a comparing circuit, and controlling the gate voltage of the MOS transistor so that both can coincide when they are different. CONSTITUTION:Potentials at a point E and a point F are compared by a voltage comparing circuit 6, and a G point potential changed according to the difference is outputted to the base of a transistor T7. According to it, a voltage at a point C is changed, and the potentials at the point E and point F are always made equal. Since current values i2 and i5 are decided by resistances R2 and R3, the ratio of the currents i2 and i5 are fixed. Since a current i7 is changed according to the i5 when a transistor Q1 is on, the current i7 has the same temperature characteristic as a current i9.

Description

[Detailed Description of the Invention] [Summary of the Invention] Regarding a semiconductor device in which a bipolar transistor and a MOS transistor are formed on the same chip, the current value of the MOS transistor used as a constant current source of an ECL circuit is determined by the current value of the constant current source of the bipolar transistor. The first ECL uses a MOS transistor as a constant current source, aiming to equalize the current value.
In a semiconductor device in which a circuit and a second ECL circuit using a bipolar transistor as a constant current source are formed on the same chip, a first constant current source using a MOS transistor and its load and a bipolar transistor are used. a second constant current source and its load;
a voltage comparison circuit that compares the voltage at a connection point between the constant current source and its load and controls the MO3+- transistor of the first constant current source with a voltage according to the difference; The base of the bipolar transistor of the source is connected to the base of the bipolar transistor of the constant current source of the second ECL circuit.
- the gate of the MOS transistor used as the constant current source of the first ECL circuit so as to apply the output voltage of the voltage comparator circuit. .

[Industrial application field]

The present invention relates to a semiconductor device in which a bipolar transistor and a MOS transistor are formed in the same size, and in particular to an ECL thereof.
Regarding a constant current source.

Since a series circuit of a bipolar transistor and a resistor can be realized with an M○S transistor element, the degree of construction can be improved by using a MOS transistor as a constant current source of a high-speed ECL circuit using a bipolar transistor. Further, an ECL circuit using a MOS transistor as a constant current source can be easily controlled to be powered down when unnecessary.

[Conventional technology]

Semiconductor devices that combine bipolar transistors and MOS transistors on the same chip are generally B1CMOS (
or Bimon OS). In this B1CMOS or BiMOS, the constant current source in the ECL circuit can be replaced with a MOS transistor. In the example in Figure 3, E
The constant current source bipolar transistor T1 of the CL circuit 9 is replaced with a MOS transistor Q in the ECL circuit 7'.

The ECL circuit 7' using a MOS transistor Q1 as a constant current source performs 0N10FF of the current 17' by controlling the gate voltage of the transistor Q1 with a switch circuit (power down circuit) 8', thereby providing a power down function. be able to.

In other words, when the control power A of the circuit 8' is L (low), the output B is H (high), that is, approximately Vcc (here, GND).
Therefore, the MOS transistor Q, which is a constant current source, is turned on and a predetermined current 17' flows. On the contrary, when input A is H, output B is L, that is, almost vhg, so the MOS
) The transistor Q1 is turned off and enters a power-down state in which no current 17' flows.

Note that 1 is a constant voltage source that applies a constant voltage to the base of the bipolar transistor T1 and applies it to a constant current source.

[Problem to be solved by the invention]

In the conventional B1CMOS (BiMOS) mentioned above,
The current 17' of the constant current source on the ECL circuit 7' side is a MOS
Transistor Q] manufacturing variations (e.g. gate length,
(gate oxide film thickness, etc.), which causes variations in power consumption and output amplitude.

Furthermore, when a basic ECL circuit 9 having a constant current source consisting of a bipolar transistor T1 and no power-down function is used, the current i7' of the ECL circuit 7 and the current 19 of the ECL circuit 9 vary depending on temperature, power supply voltage, etc. Since the output amplitudes have different dependencies on the signals, the output amplitudes of each signal also vary independently, resulting in a problem that the noise margin becomes small.

It is an object of the present invention to solve this problem and to make the current value of a MOS transistor used as a constant current source of an ECL circuit equal to the current value of a constant current source made of a bipolar transistor.

[Means to solve the problem]

FIG. 1 is a diagram of the principle of the present invention, and 2 is the same voltage as the constant current source transistor of the ECL circuit 9 (output voltage B of the constant voltage source 1).
Constant current source using bipolar transistor that can add 3
5 is a load that converts the current flowing through the transistor into voltage E; 5 is a constant current source using an MQS transistor to which the same voltage (output voltage C) as the constant current source transistor of the ECL circuit 7 is applied; 4 is the current flowing through the MOS transistor. 6 is a voltage comparator circuit that compares the voltages E and F and outputs a voltage C that changes according to the difference.

The voltage C is applied to the constant current source MOS transistor of the ECL circuit 7 via the power down control circuit 8.

[Effect]

In order to solve the conventional problems, it is necessary to ensure that the current flowing through the constant current source of the ECL circuit 7 is independent of manufacturing variations in the MOS transistors of the constant current source, and is also independent of fluctuations in temperature and power supply voltage. It is sufficient if it is controlled so that it has the same dependence as a constant current source.

Therefore, in the present invention, the current of the constant current source 2 of the bipolar transistor provided for detection and the current of the constant current source 5 of the MOS transistor are compared using the load 3.4 and the comparison circuit 6, and if they are different, - Control the gate voltage of the MOS transistor so that it becomes the same. This allows the two constant currents to always have the same value.

(Embodiment) Fig. 2 is a circuit diagram showing an embodiment of the present invention, showing the inside of the block in Fig. 1 in detail.The constant voltage source 1 is composed of transistors T3 and T4 and a resistor. The voltage obtained by dividing the output voltage B by the resistors R1 and R2 is the voltage VB of the transistor T3.
Control is performed so that the voltage becomes H, and eventually a constant voltage B is output. A constant voltage source 1 applies a constant voltage B to the base of the transistor T2, and causes a constant current 12 to flow through the load resistor R3. Therefore, the voltage E indicates the constant current 19 of the ECL circuit 9. In the power-down control circuit 8, when not powering down, I-Landisk Qp is on and QN is off, and the voltage drop of Qp can be ignored. Therefore, the control voltage of the constant current source transistor Q (of the ECL circuit 7) is determined by voltage comparison. Equal to the output voltage C of circuit 5.

The constant current source 5 is composed of a MOS transistor Q2, and causes a current i5 to flow through the load resistor R4 in accordance with the voltage C applied to the gate. The potential at point E is -12XR3, and the potential at point F is -15XRa. (The potential is negative because Vcc is GND). The voltage comparator circuit 6 includes a transistor T5. A differential amplifier using T6 compares the potentials at points E and F, and outputs a potential at point G, which changes according to the difference, to the emitter of transistor T7. For example, in the case of ELF, the potential at point G decreases, and the potential at point C also decreases accordingly. At this time, the gate voltage of the MOS transistor Q2 decreases, so the current i5 decreases, and the potential at point F increases, so that E=F.

Conversely, if E<F, the potential at point C increases and returns to E=F. In this way, feedback control is performed so that E=F at all times. Therefore, 12XR3=i5XR4, and since R3 and R4 are constants, the ratio of 12 and i5 is kept constant.

The potential at point C is applied to the gate of MOS transistor Q1 of EC7 circuit 7 via power down circuit 8.

Circuit 8 is a power-down control circuit similar to circuit 8' in FIG.
Connected with a resistor (Qp is a P-channel MOS transistor)
, when the input A is H, the signal level is lowered to approximately VER (QN is an N-channel MOS transistor). Here, the power (current t7) of the ECL circuit 7 is controlled to 0N10FF. Since C=D when the power is ON (transistor Q1 is ON), the current 17 is controlled according to the current 12 like i5. Since the current values of ia and i7 are determined by setting the gate length and gate width of the MOS transistor, the variations on the same chip are almost the same. Therefore, E.C.L.
17 of circuit 7 is 12 of constant current source 2 regardless of manufacturing variations.
It can have the same temperature and power supply voltage dependence as 19 of the ECL circuit 9.

〔Effect of the invention〕

As explained above, according to the present invention, B1CMOS (B
In iMOS), the current value of a constant current source using MOS transistors can be kept constant regardless of manufacturing variations in MOS transistors, and the dependence on temperature, power supply voltage fluctuations, etc. can be made the same as in ECL circuits using bipolar transistors. can.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram of the present invention, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is a partial circuit diagram of a conventional BiCMO5. In FIG. 1, 1 is a constant voltage source, 2 is a bipolar constant current source, 3 is its load, 5 is an MO3 constant current source, 4 is its load, 6 is a voltage comparison circuit, and 7.9 is an ECL circuit.

Claims (1)

[Claims] 1. First E using a MOS transistor as a constant current source
In a semiconductor device in which a CL circuit (7) and a second ECL circuit (9) using a bipolar transistor as a constant current source are formed on the same chip, when the MOS transistor is turned on, the gate of the MOS transistor A first constant current source (5) using a MOS transistor and its load (4) having a gate to which a voltage equivalent to the voltage applied to the
) and its load (3), and the voltage (F, E) at the connection point between the first and second constant current sources and the load, and the first a voltage comparator circuit (6) that controls a MOS transistor of a constant current source (5), the base of the bipolar transistor of the second constant current source (2) is connected to the constant current source (9) of the second ECL circuit (9); The base of the bipolar transistor of the current source is connected to a constant voltage source (1) to apply the same voltage, and the first ECL circuit (
7) A semiconductor device characterized in that the output voltage (C) of the voltage comparator circuit (6) is applied to the gate of the MOS transistor used as the constant current source.