Signal detection method, frequency detection method, power consumption control method, signal detecting device, frequency detecting device, power consumption control device and electronic apparatus

What is this patent about?

'531 is related to the field of power management in electronic devices, specifically addressing the problem of reducing power consumption in circuits that monitor the activity of other components, such as oscillators. The background involves wasteful power consumption in circuits like pre-scalers within Phase-Locked Loops (PLLs), where bias currents continue to flow even when the monitored signal is absent, leading to unnecessary energy dissipation.

The underlying idea behind '531 is to detect the presence or absence of a signal by monitoring the through current in a circuit comprised of a p-type and an n-type transistor connected in series, with the input signal applied to their gates. The key insight is that this through current only flows when the input signal is transitioning between high and low states. If the signal stops toggling, the through current ceases, indicating inactivity.

The claims of '531 focus on a signal detection method and device that uses the presence or absence of a through current in a CMOS-like structure (p-type and n-type transistors in series) to determine if an input signal is active. Specifically, the independent claims cover methods and devices for detecting the signal, determining if the signal is oscillating or static, detecting the frequency of the signal, and controlling power consumption based on the signal's activity.

In practice, the invention works by connecting the output of a component, such as an oscillator, to the gates of a series-connected p-type and n-type transistor pair. A current mirror circuit monitors the current flowing through this transistor pair. When the oscillator is running, the signal toggles, causing a brief through current to flow each time the transistors switch states. This through current is detected by the current mirror, indicating activity. If the oscillator stops, the through current stops, and after a predetermined time, a power consumption reduction signal is generated.

This approach differs from prior solutions that rely on detecting high or low states separately, which require more complex circuitry. It also avoids the slow response times associated with DC blocking capacitors used to detect signal stoppage. By directly sensing the switching activity through the through current, the invention provides a simple and efficient way to determine if a signal is present and oscillating, enabling a quick and reliable power-saving mechanism.