Does higher frequency really require more power in electronic circuits?

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Discussion Overview

The discussion revolves around the power requirements for generating signals at different frequencies in electronic circuits, specifically comparing low frequencies (e.g., 50 MHz) to higher frequencies (e.g., 2.4 GHz). Participants explore the implications of frequency on power consumption, considering factors such as parasitic components and circuit design.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a transistor oscillator at 2.4 GHz indeed uses more power than one at 50 MHz, suggesting that this is a common belief.
  • Another participant acknowledges that higher frequencies typically require more power due to the influence of parasitic components, which become significant at higher frequencies, affecting rise time and necessitating increased running current.
  • A later reply mentions that Teflon PCBs are relevant to the discussion, implying that material choice may impact performance at higher frequencies.
  • Another participant elaborates that as frequency increases, traces in the circuit behave like transmission lines with finite impedance, which also contributes to the need for higher current to drive the circuit effectively.

Areas of Agreement / Disagreement

Participants express differing views on the extent to which higher frequency circuits require more power, with some agreeing on the general trend while others provide specific conditions and factors that influence this relationship. The discussion remains unresolved regarding the definitive power requirements across different frequencies.

Contextual Notes

Participants mention various factors such as parasitic capacitance, trace impedance, and the ideal versus real behavior of components, indicating that assumptions about ideal circuit behavior may not hold in practical applications.

dnyberg2
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Can someone please explain to me the truth regarding the generation of a signal at a low frequency versus a higher frequency? I'm led to believe that a simple transistor oscillator operating at say 50 MHz uses MUCH less power than a one transistor oscillator that generates a 2.4 GHz carrier. Is this true and if so why?
 
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Yes and no! Yes in most case. Only because at higher frequency, you have to take into a lot more parasitic components that don't matter at 50MHz. Like rise time is hurt by parasitic capacitance in the circuit. Only way to make it fast is the increase the running current of the circuit so it can overcome the capacitance by just charge it faster! In idea transistor and circuits, there should not be any difference, but nothing is ideal.

Even transistors has parasitic capacitance that will speed up with higher running current.

Does it make sense?
 
Yes, so that's the reason for Teflon PCB!
 
It's not the dielectric, trace do have impedance that takes power to drive. As frequency goes up, traces start to behave like tx lines and possesses finite impedance and it take current to drive it also. Parasitic capacitance of components and others don't help. All in all, higher frequency circuits tends to need more bias current and run in higher current.
 

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