This document discusses different types of flip-flops used in circuit design, including their diagrams and operating principles. It covers conventional CMOS flip-flops, resettable flip-flops, enabled flip-flops, and differential flip-flops. For each type, it provides details on their circuit implementation and how inputs like clock, reset and enable signals determine the output. The document also briefly outlines advantages like simpler circuit design, and disadvantages like reaction time between input-output changes.

1. Presentation on circuit design
flip flop

2. CONTENTS
 INTRODUCTION
 CIRCUIT DIAGRAM
 CONVENTIONAL CMOS FLIP-FLOPS
 RESETTABLE FLIP-FLOPS
 ENABLED FLIP-FLOPS
 DIFFERENTIAL FLIP-FLOPS
 TRUE SINGLE PHASE CLK FLIP-FLOPS (TSPC)
 ADVANTAGES
 DISADVANTAGES

3. INTRODUCTION
 In electronics, a flip-flop or latch is a circuit that has two stable states and can be
used to store state information. A flip-flop is a bistable multivibrator. The circuit can
be made to change state by signals applied to one or more control inputs and will
have one or two outputs. It is the basic storage element in sequential logic. Flip-flops
and latches are a fundamental building block of digital electronics systems used in
computers, communications, and many other types of systems.
 Flip-flops and latches are used as data storage elements. Such data storage can be
used for storage of state, and such a circuit is described assequential logic. When
used in a finite-state machine, the output and next state depend not only on its current
input, but also on its current state (and hence, previous inputs). It can also be used for
counting of pulses, and for synchronizing variably-timed input signals to some
reference timing signal.

4. CONVENTIONAL CMOS FLIP-FLOPS
 Flip flops usually take a single clock signal Q and logically generate its complement
Q. If the clock rise/fall time is very slow; it is possible that both the clock and its
complement will simultaneously be at intermediate period voltage making both
transparent and increasing the flip flop hold time. In ASIC stander cell libraries, the
clock is both complemented and buffered in the flip flop cell to sharpen up the edge
rates at the expense of more inverters and clock loading.
 Recall that the flip flop also has a potential internal race condition between the two
latches.
 The turni9ng on the clock PMOS transistors in both transmission gates. If the skew
is too large, the data can sneak through both latches on the falling clock edge.
 CMOS technology allows a very different approach to flip-flop design and
construction. Instead of using logic gates to connect the clock signal to the master
and slave sections of the flip-flop, a CMOS flip-flop uses transmission gates to control
the data connections. (See the CMOS gate electronics page for a closer look at the
transmission gate itself.)
 The result is that a controllable flip-flop can be built with only inverters and
transmission gates — a very small and simple structure for an IC.

5. CIRCUIT DIAGRAM OF CONVENTIONAL CMOS FLIP-
FLOPS

6. Resetteble flip flops
 Most practicle sequencing elements require a reset signal to enter a known initial
state on startup flip flop with resert inputs.
 There are two types of reset synchronous and asynchronous.
 Asynchronous reset forces low immediately, while synchronous reset waits for the
clock.
 Synchronous resett signals must be stable for setup and the clock edge while a
synchronous reset is characterized by a propagation delay from the reset output..
 Synchronous reset simply requires ANDing the input and reset
 Asynchronous require getting both the data and the feedback to force the reset
independent of the clock.
 The trstate NAND gate can be constructed from an NAND gate in series with
clocked transmission gate.

7. Circuit diagram of Resetteble flip flops

8. ENABLED FLIP-FLOPS
 Sequencing element also often except an enable input.
 When enable is low, the element retain its state independently of the clock.
 The input multiplexer feeds back to the old stage then the element is
disabled.
 Clock getting does not affect delay from the data and the and gate can be
shared among multiple clocked elements

9. Circuit Diagram of ENABLED FLIP-FLOPS

10. DIFFERENTIAL FLIP-FLOPS
 Differential flip flops true and complementary inputs and produce
true and complementary outputs.
 They are built from a clocked sense amplifier so they can rapidly
respond to small differential input voltages, while they are larger
then an ordinary single ended flip flops having an extra inverter to
produce the complementary output.
 They work well with low swing inputs such as register file bit lines
and low swings busses.
 Differential sense amplifier flip flop receiving differential inputs
and producing a differential output.

11. CIRCUIT DESIGN OF DIFFERENTIAL FLIP-FLOPS

12. TRUE SINGLE PHASE CLOCK FLIP-FLOPS (TSPC)

14. ADVANTAGES OF CIRCUIT DESIGN FLIP FLOPS
 The main advantage of flip flop is that it have a circuit inside it
contain gates and can generate specific output, it make a complex
circuit much simpler.
 It can perform the functions of the set/reset flip-flop and has the
advantage that there are no ambiguous states.

15. DISADVANTAGES OF FLIP FLOPS
The primary disadvantages of flip flop is their reacting time
between the input signal and resultant Output if the signal changes
between this reaction time the flip flops.

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