Full Adder

A full adder circuit performs an addition of two single bit numbers, together with a Carry-In from a less significant stage, producing a Sum output and a Carry-Out to the next stage. The full adder may be constructed using a pair of half adders, plus a single logic...
Venn Diagrams and Boolean Algebra

Venn Diagrams and Boolean Algebra

A Venn diagram may be used to represent the possible logical states of a combinational logic system, typically having up to 3 input variables. Venn diagrams with more than 3 input variables becoming increasingly difficult to draw, given that for N variables, there...

Inverting Amplifier

An inverting amplifier uses an operational amplifier plus two external resistors to produce a simple amplifier. The voltage gain is given by the ratio of the two resistors, while the name of the circuit relates to the output voltage being 180° out of phase with...

Voltage Follower

A voltage follower circuit produces an output voltage which is the same as the input voltage, so the output ‘follows’ the input – hence the common circuit name. To understand the circuit operation, firstly notice the feedback connection linking the...

Differential Amplifier

This circuit amplifies the potential difference between the two input terminals, with the gain being related to the values of the four resistors. It can be shown that the output voltage Vout is related to the input voltages V1 and V2, according to the expression: It...

Half Adder

A half adder circuit performs a 1-bit binary addition, producing a Sum output and also a Carry-Out to a more significant stage. Operation of the half adder is summarised in the following truth table. The half adder may be constructed using an XOR (exclusive-or) gate,...