ECL-TO-GaAs level converting circuit

Claim 1

An apparatus for converting a first signal used in an ECL device into a second signal which has a GaAs logic level which is used in a GaAs device, using a reference signal, said apparatus comprising: a first power source line receiving a first power source voltage which is used in the ECL device; a second power source line receiving a second power source voltage which is lower than the first power source voltage and is used in the ECL device; a third power source line receiving a third power source voltage which is higher than the first power source voltage; a level converting circuit, provided within the ECL device, including emitter-coupled first and second transistors, a first resistor coupled to said third power source line and a collector of the first transistor, a second resistor coupled between said third power source line and a collector of the second transistor, and a current source coupled between said second power source line and coupled emitters of the first and second transistors, a base of said first transistor receiving one of the first signal and the reference signal, and a base of said second transistor receiving the other of the first signal and the reference signal; an output buffer part, coupled between said first and third power source lines, including a third transistor having a base coupled to the collector of said one of the first and second transistors and a collector coupled to said third power source line, said third transistor having an emitter from which the second signal is output; and a clamping circuit, coupled between said first and third power source lines, to said level converting circuit, and to the base of the third transistor, for clamping a collector potential of one of the first and second transistors so that the collector potential does not fall below a predetermined potential, and for clamping an emitter potential of the third transistor to a level substantially identical to the first power source voltage when the second signal has a low logic level, said second signal operating in a voltage range between said first and third power source voltages.

Claim 2

An apparatus for converting a first signal used in an ECL device into a second signal which has a GaAs logic level which is used in a GaAs device, using a reference signal, said apparatus comprising: a first power source line receiving a first power source voltage which is used in the ECL device; a second power source line receiving a second power source voltage which is lower than the first power source voltage and is used in the ECL device; a third power source line receiving a third power source voltage which is higher than the first power source voltage; a level converting circuit, provided within the ECL device, including emitter-coupled first and second transistors, a first resistor coupled to said third power source line and a collector of the first transistor, a second resistor coupled between said third power source line and a collector of the second transistor, and a current source coupled between said second power source line and coupled emitters of the first and second transistors, a base of said first transistor receiving one of the first signal and the reference signal, and a base of said second transistor receiving the other of the first signal and the reference signal; an output buffer part, coupled between said first and third power source lines, including a third transistor having a base coupled to the collector of said one of the first and second transistors and a collector coupled to said third power source line, said third transistor having an emitter from which the second signal is output; and a clamping circuit, coupled between said first and third power source lines, to said level converting circuit, and to the base of the third transistor, for clamping a collector potential of one of the first and second transistors so that the collector potential does not fall below a predetermined potential, and for clamping an emitter potential of the third transistor to a level substantially identical to the first power source voltage when the second signal has a low logic level, said second signal operating in a voltage range between said first and third power source voltages.

Claim 14

The apparatus for converting a first signal into a second signal of a different logic type than the first signal using a reference signal, said apparatus receiving at least first and second power supply signals, said apparatus comprising: a first transistor having a base coupled to receive the first signal; a second transistor having an emitter coupled to an emitter of said first transistor, and having a base coupled to receive the reference signal; a current source coupled to the emitters of the first and second transistors; a first resistor having a first end coupled to a collector of the transistor, and having a second end coupled to receive the first power supply signal; a second resistor having a first end coupled to a collector of the second transistor, and having a second end coupled to receive the first power supply signal; a clamping circuit including a third resistor having a first end coupled to receive the first power supply signal, a first diode having an anode coupled to a second end of the third resistor, a second diode having an anode coupled to a cathode of the first diode, and having a cathode coupled to receive the second power supply signal, and a third transistor having a base coupled to a second end of the third resistor, having a collector coupled to receive the first power supply signal, and having an emitter coupled to the collector of the second transistor; and a fourth transistor having a collector coupled to receive the first power supply signal, having a base coupled to the collector of the second transistor so that a voltage level at the emitter of the third transistor is equal to a voltage level at the base of the fourth transistor and having an emitter for outputting the second signal which operates in a voltage range between a voltage level of the first power supply signal and a voltage level of the second power supply signal, the clamping circuit causing a potential at the emitter of the fourth transistor to be substantially identical to a voltage level of the second power supply signal when the second signal is at a low voltage level.

Claim 15

The apparatus for converting a first signal into a second signal of a different logic type than the first signal using a reference signal, said apparatus receiving at least first and second power supply signals, said apparatus comprising: a first transistor having a base coupled to receive the first signal; a second transistor having an emitter coupled to an emitter of said first transistor, and having a base coupled to receive the reference signal; a current source coupled to the emitters of the first and second transistors; a first resistor having a first end coupled to a collector of the transistor, and having a second end coupled to receive the first power supply signal; a second resistor having a first end coupled to a collector of the second transistor, and having a second end coupled to receive the first power supply signal; a clamping circuit including a third resistor having a first end coupled to receive the first power supply signal, a first diode having an anode coupled to a second end of the third resistor, a second diode having an anode coupled to a cathode of the first diode, and having a cathode coupled to receive the second power supply signal, and a third transistor having a base coupled to a second end of the third resistor, having a collector coupled to receive the first power supply signal, and having an emitter coupled to the collector of the second transistor; and a fourth transistor having a collector coupled to receive the first power supply signal, having a base coupled to the collector of the second transistor so that a voltage level at the emitter of the third transistor is equal to a voltage level at the base of the fourth transistor and having an emitter for outputting the second signal which operates in a voltage range between a voltage level of the first power supply signal and a voltage level of the second power supply signal, the clamping circuit causing a potential at the emitter of the fourth transistor to be substantially identical to a voltage level of the second power supply signal when the second signal is at a low voltage level.