A symmetrical current source 10 has a pnp current source 11 including four npn transistors Q1-Q4 and a pnp output transistor Q28 and an npn current sink 12 including pnp transistors Q5-Q8 and an output transistors Q29. In current source 11 cross coupled transistors Q3, Q4 establish a predetermined bias for source 11; cross coupled transistors Q7, Q8 establish a predtermined bias for sink 12.
Gabriel J. Uscategui - West Melbourne FL Glenn Wells - Palm Bay FL
Assignee:
Harris Corporation - Melbourne FL
International Classification:
H03F 345 H03F 330
US Classification:
330255
Abstract:
Circuits and methods to minimize total harmonic distortion in an integrated circuit feedback amplifier. Complementary transistors in the signal path are selected so that their base-to-collector capacitances are matched. Additionally, the DC operating currents of such transistors are matched, thereby cancelling non-linearities due to base-to-collector capacitances.
Method Of Fabricating Low Noise Reference Diodes And Transistors
John S. Prentice - Palm Bay FL Gabriel J. Uscategui - Melbourne FL
Assignee:
Harris Corporation - Melbourne FL
International Classification:
H01L 2104 H01L 2940
US Classification:
29571
Abstract:
The thick oxide over the surface portion of a P/N junction of a reference diode is removed, a thin oxide is grown thereon, and a contaminated shield layer is formed on the thin oxide. In addition to improving the reversed biased diode, the same method improves the forward biased emitter-base surface junction of a vertical bipolar transistor. The shield layer may be biased separate from the transistor.
Differential Longitudinal Amplifier For A Subscriber Line Interface Circuit
Leonel Ernesto Enriquez - Melbourne Beach FL Gabriel Julio Uscategui - West Melbourne FL
Assignee:
Harris Corporation - Melbourne FL
International Classification:
H04M 1900
US Classification:
379399
Abstract:
A circuit and method for sensing and compensating for longitudinal (common mode) signals in a subscriber loop of a telephone system. The circuit and method may include a longitudinal amplifier for sensing a difference between a reference voltage, V. sub. BAT /2, and a longitudinal voltage in the subscriber loop, and for providing four currents, two to each of two current amplifiers in the telephone system subscriber line interface circuit (SLIC). The longitudinal amplifier includes two current mirrors, each for providing two currents of the same polarity and of the same magnitude. The magnitude of the difference between the two currents being provided to each of the current amplifiers is proportional to the voltage difference. When compensation of the longitudinal signals has been achieved, the two voltages are the same and the magnitudes of the four currents are the same.