As stated on page diode logic, the basic problem with the gates of DL is that the logic signal deteriorate rapidly. However, working for a stage at a time, if the re-amplified signal between the doors. The Diode-Transistor Logic (DTL) achieves that goal.
The top door is a door or DL \u200b\u200bfollowed by an investor as seen in the page resistor-transistor logic. OR function is still performed by the diodes. However, regardless of the number of entries in the logic 1, is surely enough input voltage to drive the transistor into saturation. Only if all inputs are at logic 0 then the transistor will remain off. The advantage of this circuit on the equivalent of RTL is the logical OR is performed by diodes, resistors next. Therefore there is no interaction between various inputs, and any number of diodes can be used. A disadvantage of this circuit is the input resistor to the transistor. Their presence tends to slow the circuit the low state, thus limiting the rate at which the transistor can switch states.
At first glance, the NAND version shown above should eliminate this problem. Can any logical 0 input immediately pull down the base of the transistor and switch transistor off state? Well, not quite. Remember that the input voltage of 0.65 volts base for the transistor? The diodes exhibit a voltage bias very similar when conducting current. Therefore, even with all the entries in the land, the base of the transistor will be about 0.65 volts and the transistor can drive.
To solve this problem, we can add a diode in series with the base of the transistor, as shown above. Now the bias voltage is needed to polarize the transistor is 1.3 volts directly. For even more secure, we could add a second diode of the series and require 1.95 volts to drive the transistor. In this way we also make sure that temperature changes do not significantly affect circuit operation. Either way, this circuit will work as a NAND gate. In addition, we can use as many diodes in the input as we want without raising the threshold voltage. Furthermore, without the resistor in series in the input circuit, there is less effect of delayed, so the door can switch states faster and handle higher frequencies.
The top door is a door or DL \u200b\u200bfollowed by an investor as seen in the page resistor-transistor logic. OR function is still performed by the diodes. However, regardless of the number of entries in the logic 1, is surely enough input voltage to drive the transistor into saturation. Only if all inputs are at logic 0 then the transistor will remain off. The advantage of this circuit on the equivalent of RTL is the logical OR is performed by diodes, resistors next. Therefore there is no interaction between various inputs, and any number of diodes can be used. A disadvantage of this circuit is the input resistor to the transistor. Their presence tends to slow the circuit the low state, thus limiting the rate at which the transistor can switch states.
At first glance, the NAND version shown above should eliminate this problem. Can any logical 0 input immediately pull down the base of the transistor and switch transistor off state? Well, not quite. Remember that the input voltage of 0.65 volts base for the transistor? The diodes exhibit a voltage bias very similar when conducting current. Therefore, even with all the entries in the land, the base of the transistor will be about 0.65 volts and the transistor can drive.
To solve this problem, we can add a diode in series with the base of the transistor, as shown above. Now the bias voltage is needed to polarize the transistor is 1.3 volts directly. For even more secure, we could add a second diode of the series and require 1.95 volts to drive the transistor. In this way we also make sure that temperature changes do not significantly affect circuit operation. Either way, this circuit will work as a NAND gate. In addition, we can use as many diodes in the input as we want without raising the threshold voltage. Furthermore, without the resistor in series in the input circuit, there is less effect of delayed, so the door can switch states faster and handle higher frequencies.
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