Bus transceiver including compensation circuit for variations in electrical characteristics of components
AssigneeDigital Equipment Corporation
InventorsWayne C. Parker, John W. May
Life of this patent
Estimating the term…
Abstract
A bus transceiver having a driver with charging/discharging characteristics that are device-independent and a receiver that provides adequate noise immunity is described. The transceiver uses a reference network to modulate the conductance of a depletion device as a function of device parameter variations in order to maintain a constant response time for the driver and optimize peak current. The receiver uses a modified differential amplifier to provide high gain and hysteresis sufficient for a desired level of noise immunity.
Claims12
A bus driver system in a monolithic integrated circuit for driving an external bus in response to a data signal, the system comprising:
- A. selectively energizable driver means for connection to the external bus and having an energized state and a de-energized state, said driver means driving the bus when in the energized state;
- B. pre-driver means connected to said driver means for selectively energizing and de-energizing said driver means in response to the data signal and a reference signal, said pre-driver means being responsive to the reference signal to adjust the rate at which it switches said driver means between energized and de-energized states;
- C. reference means connected to said pre-driver means for generating said reference signal, said reference means comprising:
- i. characteristic reference signal generating means comprising pre-driver compensating means and driver compensating means each having a electrical characteristic which varies with variations in the same electrical characteristic in said pre-driver means and said driver means, respectively, said driver compensating means and said pre-driver compensating means being interconnected to generate a characteristic reference signal, and
- ii. reference signal generating means for generating said reference signal in response to said characteristic reference signal.
A bus transceiver system in a monolithic integrated circuit for driving an external bus in response to a data signal and for receiving data signals from said bus, the system comprising:
- A. selectively energizable driver means for connection to the external bus and having an energized state and a de-energized state, said driver means driving the bus when in the energized state;
- B. pre-driver means connected to said driver means for selectively energizing and de-energizing said driver means in response to the data signal and a reference signal, said pre-driver means being responsive to the reference signal to adjust the rate at which it switches said driver means between energized and de-energized states;
- C. reference means connected to said pre-driver means for generating said reference signal, said reference means comprising:
- i. characteristic reference signal generating means comprising pre-driver compensating means and driver compensating means each having a electrical characteristic which varies with variations in the same electrical characteristic in said pre-driver means and said driver means, respectively, said driver compensating means and said pre-driver compensating means being interconnected to generate a characteristic reference signal, and
- ii. reference signal generating means for generating said reference signal in response to said characteristic reference signal;
- and
- D. a receiver stage for connection to said bus and including high-gain means for producing a voltage output signal as a function of a signal on said bus.
Dependencies are inferred from the claim text.