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# Clock Driver, Translator and Latch Circuit

IP.com Disclosure Number: IPCOM000047797D
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 3 page(s) / 41K

IBM

## Related People

Davis, JW: AUTHOR [+2]

## Abstract

Differential Cascode Current Switch (DCCS) circuitry provides for complex functions in a single circuit (tree). Here, three mutually exclusive clocks are generated and are used to clock three separate data conditions into a latch. Fig. 1 shows three DCCS circuits used to generate three distinct clocks. The trees form NAND functions, but are not limited to a simple NAND function. OSC X, Y, Z may be different times during a cycle or they may be the same time with f(a) through f(1) defining different conditions or different instructions. OSC X, Y, and Z plus f(a) through f(1) must guarantee that one and only one of the signals latch hold, X clock, Y clock, and Z clock is present at any one time (+ level). The operation of the clock generation trees is as follows.

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Clock Driver, Translator and Latch Circuit

Differential Cascode Current Switch (DCCS) circuitry provides for complex functions in a single circuit (tree). Here, three mutually exclusive clocks are generated and are used to clock three separate data conditions into a latch. Fig. 1 shows three DCCS circuits used to generate three distinct clocks. The trees form NAND functions, but are not limited to a simple NAND function. OSC X, Y, Z may be different times during a cycle or they may be the same time with f(a) through f(1) defining different conditions or different instructions. OSC X, Y, and Z plus f(a) through f(1) must guarantee that one and only one of the signals latch hold, X clock, Y clock, and Z clock is present at any one time (+ level). The operation of the clock generation trees is as follows. When OSC X, Y, and Z are all - (inactive), one current path in each tree will cause +X clock, +Y clock, and +Z clock all to be -. The latch hold signal line will go to a + level and all four output signals will conform to the rule that one and only one signal will be + at all times. At some later time, f(a), f(b), f(c), f(d), and OSC X will all go +. This will cause the current flow path in tree 1 to change so that the latch hold signal will go - and the X clock signal will go to +. In all cases, there will be one and only one current flow path in each tree and one and only one output at a + level. In a similar manner, trees 2 and 3 also cause the latch hold line to go to a - level and outputs clock Y and clock Z can go to a + level depending on which tree has all + inputs. The four signals are then translated down one or more levels (four levels shown) and sent to the latch circuit in Fig. 2. The latch tree in Fig. 2 has four transistors at the bottom of the tree. Since the clock driver circuit in Fig. l guarantees one and only one + signal at any time, the latch tree will always have one and only one current path active at all times. If clock X is +, for example, data inputs X1, X2, X3, and X4 will be examined, and if all + will cause the latch to be set to a one, while if one or more inputs are -, the latch will be set to a zero. When the X clock goes -, the latch hold signal will go + and hold the contents of the latch in the state previously set.

Similarly, clocks Y and Z can be used to set the latch to a zero or one. Note that a minimum of data inputs X1, Y1, and Z1 are required for proper operation of the latch while inputs X2, X3, X4, Y2, Y3, Y4, Z2, Z3, and Z4 are optional. There is no maximum limit on X data, Y data, or Z data inputs exc...