Motorola Corporation

Tzu-Hui P Hu

Barry B Heim

Michael W Hodel

William F Johnstone

C Christopher Hanke, Iii

An output circuit (40) includes pull-up transistor (12), two pull-down transistors (14, 16), and a noise suppression circuit (58). When an input node (50) of the output circuit (40) switches to a logic high voltage, the pull-up transistor (12) is switched off. A first transistor (22) in the noise suppression circuit (58) is switched on, discharges a capacitive load (32) coupled to an output node (60) of the output circuit (40), and charges a capacitor formed by a second transistor (24) in the noise suppression circuit (58). After a time delay, the two pull-down transistors (14, 16) are switched on sequentially and establish two current paths from the output node (60) to ground (25). Then, a third transistor (56) in the noise suppression circuit (58) is switched on, discharges the capacitor (24), and establishes a third current path from the output node (60) to ground.

Output circuit and method for suppressing switching noise therein

An input circuit (10) includes two inverters (12, 16) and an enable transistor (18). When a logic high enable signal is transmitted to a gate electrode of the enable transistor (18). The two inverters (12, 16) form a latch that holds the data at the input port (21) of the input circuit (10). When a logic low enable signal is transmitted to the gate electrode of the enable transistor (18), the latch formed by the two inverters (12, 16) is disabled, thereby allowing fast data transmission through the input circuit (10). When the voltage at the input port (21) is higher than a supply voltage of the input circuit (10), the enable transistor (18) switches off to protect a voltage supply coupled to the input circuit (10).

Input circuit and method for holding data in mixed power supply mode

A delay matching circuit has a first node (48), a second node (50), a first loading circuit (54, 56), a second loading circuit (58, 60), a third loading circuit (64) and a buffer circuit (62). The first loading circuit couples a first logic state to the first node responsive to a first state of a control signal. The second loading circuit couples a second logic state to the first node responsive to a second state of the control signal. The buffer circuit electrically couples the first and second nodes. The first loading circuit, second loading circuit and buffer circuit are characterized by a first, a second and a third predetermined electrical impedance, respectively. The third loading circuit is coupled to the second node and is characterized by a fourth predetermined electrical impedance. The disclosed delay matching circuit propagates a clock signal input with a delay equal to the Clock-to-Q delay associated with a flip-flop constructed with similar circuit elements. The disclosed delay matching circuit is useful in circuits, such as phase locked loops, where the simultaneous propagation of two signals is critical.

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Tempe, AZ, United States of America

Tzu-Hui P Hu