Digital signal processing key terms

Truth Table

A tabular representation of all possible input combinations and the corresponding output of a logic circuit.

Logic Gate Symbol

A standardized diagrammatic symbol that represents a specific logic gate in a circuit.

AND gate

AND gate is a precise Combinational logic term in AQA A-Level Physics electronics. A logic gate that outputs true only when all its inputs are true. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Boolean expression

A symbolic representation of a logical relationship using Boolean variables and operators.

Combinational logic circuit

A circuit whose output depends only on the present input values and not on any previous inputs or internal state.

Boolean expression

A mathematical representation of a logic circuit using Boolean algebra, combining logic gates with AND, OR, and NOT operations.

Sequential logic

Logic circuits whose output depends on the current input and on past inputs, requiring memory elements such as latches or flip‑flops.

Combinational logic

Logic circuits whose output depends only on the current input, with no memory elements.

Latch

Latch is a precise Sequential logic term in AQA A-Level Physics electronics. A bistable circuit that holds a state until an input changes it. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Flip‑flop

Flip‑flop is a precise Sequential logic term in AQA A-Level Physics electronics. A bistable circuit that changes state on a clock edge, storing one bit of data. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Timing diagram

A graphical representation showing the states of signals over time in a digital circuit.

Sequential circuit

A digital circuit whose output depends on current inputs and past states, typically using memory elements such as latches or flip‑flops.

clock signal

A periodic electrical pulse that synchronises the operation of sequential logic circuits, ensuring that state changes occur at defined times.

clock frequency

The number of clock pulses per second, measured in hertz, which determines the maximum rate at which a sequential circuit can update its state.

Oscillation period

The time taken for one complete cycle of oscillation in a periodic signal, measured in seconds.

Frequency

The number of oscillations per unit time, the reciprocal of the period, measured in hertz (Hz).

Astable Multivibrator

A two‑transistor or two‑IC circuit that continuously oscillates, producing a square‑wave output without a stable state.

Duty Cycle

The proportion of one period in which a signal is high, expressed as a percentage of the total period.

logic gate

logic gate is a method cue for Combinational logic. Use it when working on "Identify common logic gates and symbols." and state the specific calculation, notation, or reasoning role it plays rather than treating it as a loose label.

Identify

Identify is a notation check for Combinational logic. Use it when working on "Identify common logic gates and symbols." and state the specific calculation, notation, or reasoning role it plays rather than treating it as a loose label.

common

common is a exam vocabulary marker for Combinational logic. Use it when working on "Identify common logic gates and symbols." and state the specific calculation, notation, or reasoning role it plays rather than treating it as a loose label.

feedback

feedback is used in Combinational logic to describe a specific electronics relationship between an input condition, a component response, and an output signal. In AQA A-Level Physics, define it in circuit context and explain how it changes the behaviour measured or observed.

astable

astable is a method cue for Astables. Use it when working on "Describe the function of an astable circuit." and state the specific calculation, notation, or reasoning role it plays rather than treating it as a loose label.

Describe

Describe is used in Astables to describe a specific electronics relationship between an input condition, a component response, and an output signal. In AQA A-Level Physics, define it in circuit context and explain how it changes the behaviour measured or observed.

function

function is a exam vocabulary marker for Astables. Use it when working on "Describe the function of an astable circuit." and state the specific calculation, notation, or reasoning role it plays rather than treating it as a loose label.

circuit

circuit in Astables means the specific circuit idea used when analysing a medical sensor amplifier. Define it by stating what changes at the input, how the relevant component or circuit block responds, and what output or measurement follows. This keeps the term distinct from nearby electronics vocabulary and ties it to the AQA A-Level Physics objective.

duty cycle

duty cycle is a method cue for Astables. Use it when working on "Explain duty cycle qualitatively." and state the specific calculation, notation, or reasoning role it plays rather than treating it as a loose label.

Explain

Explain is used in Astables to describe a specific electronics relationship between an input condition, a component response, and an output signal. In AQA A-Level Physics, define it in circuit context and explain how it changes the behaviour measured or observed.

cycle

cycle is a exam vocabulary marker for Astables. Use it when working on "Explain duty cycle qualitatively." and state the specific calculation, notation, or reasoning role it plays rather than treating it as a loose label.

qualitatively

qualitatively in Astables means the specific circuit idea used when analysing a laboratory comparator output. Define it by stating what changes at the input, how the relevant component or circuit block responds, and what output or measurement follows. This keeps the term distinct from nearby electronics vocabulary and ties it to the AQA A-Level Physics objective.