Device for complementary input signals using two circuits with different threshold voltages

• US 4,651,033 A
• Filed: 01/27/1984
• Issued: 03/17/1987
• Est. Priority Date: 01/31/1983
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Yasutake, Nobuyuki, Tsuda, Toshitaka
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Hudspeth, D. R.
• Application Number:
  US06/574,725
• Time in Patent Office: 1,145 Days
• Field of Search: 307/200 A, 307/443, 307/454-455, 307/494, 307/530, 307/350, 307/355, 307/360, 307/243, 307/254, 307/297, 307/315, 340/347 DA, 330/252, 330/261, 365/190, 365/208
• US Class Current: 327/483
• CPC Class Codes: H03K 17/04126 in bipolar transistor switches
• CPC Class Codes: H03K 17/14 Modifications for compensating variations of physical values, e.g. of temperature
• CPC Class Codes: H03K 17/603 with coupled emitters

Abstract

A differential switching circuit includes a first current switching circuit having a first input terminal; a second current switching circuit having a second input terminal and a threshold different from that of the first circuit; and a constant current source commonly connected to the first and second circuits. Complementary input signals are applied to the first and second input terminals.

Claims

1. A differential switching circuit receiving complementary first and second input signals, said circuit comprising:

a first current switching circuit having a first input terminal operatively connected to receive the first input signal, and having a first switching threshold voltage;

a second current switching circuit, operatively connected to said first current switching circuit, having an output terminal and a second input terminal, for receiving the second input signal, and having a second switching threshold voltage different from the first switching threshold voltage; and

a constant current source having a circuit end commonly connected to said first and second current switching circuits.

2. A differential switching circuit according to claim 1, wherein each of said first and second current switching circuits comprises an n-p-n type transistor.

3. A differential switching circuit according to claim 1,

wherein said first current switching circuit comprises a first transistor operatively connected to said constant current source, ground and the first input terminal, and

wherein said second current switching circuit comprises:

a second transistor having a collector operatively connected to ground, a base operatively connected to receive the second input signal and an emitter; and

a third transistor having a collector operatively connected to the collector of said second transistor, a base operatively connected to the emitter of said second transistor and an emitter operatively connected to said constant current source.