Taajuusjakomo

Taajuusjakomo, or frequency divider, is an electronic circuit that outputs a periodic signal whose frequency is a submultiple of the input frequency. For an input frequency fin, the output frequency fout is typically fin divided by an integer N (fout = fin / N).

Most taajuusjakamot are digital. They use counters, flip-flops, or logic gates to count input cycles and toggle or reset after N cycles, producing a waveform with a longer period. A basic divide-by-2 can be implemented with a toggle flip-flop; higher divides use asynchronous ripple counters or synchronous counters. Programmable dividers allow selecting N at runtime. Prescalers are broad-division stages used to reduce very high frequencies before feeding a phase-locked loop.

Analog approaches using RC networks or transformers exist for lower frequencies but are less common in modern CMOS-era systems.

Applications include clock generation and distribution in digital systems, frequency synthesis in phase-locked loops, radio receivers and transmitters, and test and measurement equipment. Key design considerations are jitter and phase noise, output duty cycle, maximum input frequency, and power consumption.

Examples: divide-by-2 with a toggle flip-flop; divide-by-10 with a binary counter plus modulo-10 logic; programmable dividers such as fixed N or powers of two. In PLLs, a high-speed prescaler (for example divide-by-4) precedes the programmable divider, enabling synthesis from very high reference frequencies. Taajuusjakamot are fundamental in controlling timing and frequency relationships across electronic systems.