US 4,727,265 AGranted

Semiconductor circuit having a current switch circuit which imparts a latch function to an input buffer for generating high amplitude signals

AssigneeHitachi, Ltd.

InventorsHiroaki Nanbu, Noriyuki Honma, Kunihiko Yamaguchi, Kazuo Kanetani, Goro Kitsukawa

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Abstract

A semiconductor circuit of a current mode type logic is provided having a reference voltage generating circuit which generates the reference voltage to be applied to the logic circuit in response to a clock signal to latch the state corresponding to an input signal at an instant of the clock signal input. The reference voltage has three levels in response to the voltage levels of the clock signal and the input signal: a middle voltage between the two high and low voltage levels of the input signal when the clock signal is at a first level voltage; a voltage higher than the high voltage level of the input signal when the clock signal is at a second level voltage and the output signal is at a high voltage; and a voltage lower than the low voltage level of the input signal when the clock signal is at a second level voltage and the output signal is at a second level voltage and the output signal is at a low voltage. This semiconductor circuit can relax restrictions on the signal amplitude due to the supply voltage and the saturation of the transistors, and, accordingly, allows processing signals having a much greater amplitude than was previously possible.

Claims6

Dependent claims

A semiconductor circuit comprising a current switch circuit including:

a first transistor having its base fed with an input signal having a high voltage level and a low voltage level, said first transistor generating an output signal at its collector;
a second transistor having its base fed with a reference voltage and its emitter connected with the emitter of said first transistor;
a current source connected commonly with the emitter of said first transistor and the emitter of said second transistor;
and
a reference voltage generating circuit having first and second input terminals fed with a clock signal and said output signal, repectively, and an output terminal generating said reference voltage which is applied to the base of said second transistor,
wherein said reference voltage generating circuit includes means to generate three kinds of voltages:
a middle voltage which is intermediate between the high voltage level and the low voltage level of the input signal when said clock signal is at a first voltage level;
a voltage higher than the high voltage level of the input signal when said clock signal has a second voltage level and when an output signal of said semiconductor circuit is at a high voltage level;
and a voltage lower than the low voltage level of the input signal when said clock signal is at the second voltage and when said output signal is at a low voltage, whereby said reference voltage generator operates said current switch circuit in response to said input signal and said clock signal to latch the state corresponding to an input signal at an instant when said clock signal is input.

6 more elements

A semiconductor circuit comprising a current switch circuit including:

a first transistor having its gate fed with an input signal having a high voltage level and a lower voltage level, said first transistor generating an output signal at its drain;
a second transistor having its gate fed with a reference voltage and its source connected with the source of said first transistor;
a current source connected commonly with the source of said first transistor and the source of said second transistor;
and
a reference voltage generating circuit having first and second input terminals fed with a clock signal and said output signal, resepectively, and an output terminal generating said reference voltage which is applied to the gate of said second transistor,
wherein said reference voltage generating circuit includes means to generate three kinds of voltages:
a middle voltage which is intermediate between the high voltage level and the low voltage level of the input signal when said clock signal is at a first voltage level;
a voltage higher than the high voltage level of the input signal when said clock signal has a second voltage level and when an output signal of said semiconductor circuit is at a high voltage level;
and voltage lower than the low voltage level of the input signal when said clock signal is at the second voltage and when said output signal is at a low voltage, whereby said reference voltage generator operates said current switch circuit in response to said input signal and said clock signal to latch the state corresponding to an input signal at an instant when said clock signal is input.

6 more elements

Dependencies are inferred from the claim text.