Transistor latch

There was another moment of truth in the ballast project I described in Chapter 1, when we had ordered several new boards with its innovative 2N2222-2N2907 npn-pnp latch. But the protection latch on all these boards was not working at all. Design issue We looked hard at the transistors and thought they were OK. After a couple of days we took the transistors out, finally suspecting they were faulty (maybe inadequate hfe, etc.), and then made a discovery—we learned that so-called 2222 transistors do not even have the same pinouts Each manufacturer... 

Based on this design a memory/adder model (Fig. 6(c)) using 464 transistors could be constructed and evaluated on grounds of SPICE circuit simulations. Four bits of information were read from four different memory cells, added as two 2-bit words, and the resulting 2-bit was moved through registers (clocked D-latches) to a subsequent computation. It must be noted... 

One functional gate dielectric of interest to a number of groups is using a ferroelectric material to retain state in transistor devices. This has a range of applications including latching circuits [97] and memory storage elements... 

Fig. 7.1. Two architectures for display driving, (a) shows a single transistor architecture appropriate for latching and holding charge on the pixel for field driven display elements such as liquid crystal displays or e-Ink. (b) schematically shows the matrixed version of this element, (c) shows a two transistor voltage-programmed current driver appropriate for OLEDs. More advanced voltage and current programmed circuits are also possible, but require more transistors.

In a voltage programmed drive circuit, the voltage on the gate of the drive transistor is driven directly and latched through switches on the backplane. While relatively simple to implement, this has several disadvantages ... 

Fig. D.6. (a) A simple T-flip flop implemented using NAND gates (b) the symbol for a T flip-flop. Q is the output, Q is the inverse of the output. When a rising clock edge is applied to T, the state switches from on to off or vice versa. More sophisticated latches may be necessary to prevent race conditions depending on the transistors used.

The parallel port/printer adapter in a PC was previously intended to connect printers to computers. However, it was also used for connecting other devices to PCs. The printer adapter has three independent transistor-transistor logic (TTL) compatible ports an 8-bit output-data port, a 4-bit output-control port with open-collector drivers, and a 5-bit input-status port. The two output ports also have input registers at identical addresses. Writing to the data register causes the byte sent to be latched and to appear on the parallel port s 25-pin D-type connector. Reading this register returns the contents of the latch. Parallel ports have also been extensively used in measurement applications. The main... 

Table 5.1 shows a comparison of the synthesis statistics for these architectures with the SIMPLE architecture, which contains no initialization function. In terms of transistors, synchronous initialization makes the basic circuit approximately one-third larger. The additional gate between each flip flop also increases the latch to latch delay. 

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