By hvhipot 
Many digital systems suffer from excessive power noise at frequencies related to the system clock. Can the series resonance (also known as the series resonance test withstand voltage device) circuit (such as the circuit in Figure 1) connected between the power supply and the ground plane attenuate this noise? The answer can be, but the prerequisite is that HV Hipot Electric Co., Ltd. circuit meets the following impossible conditions.
Firstly, the frequency of the system clock must be kept fixed. In systems without crystal controlled clocks, the clock frequency may drift by ± 30% or higher. Low power systems typically lower the clock when idle to save power. High performance systems sometimes provide speed variables, for which customers need to pay extra to obtain performance. As a diagnostic test, designers can slow down the system clock to display certain timing related faults. Under these conditions, it is not possible to adopt a power supply noise mitigation strategy that carefully adjusts the precise noise frequency.
The allure of a series resonant circuit is that it allows for the use of smaller capacitor values, and if you match the capacitor with appropriate inductance and resistance values, you can use smaller capacitor values to produce the series resonant effect. Unfortunately, the smaller the capacitor, the more precise the circuit must become.
For example, a capacitor with one-fifth of its normal value requires a tolerance of ± 10% for both the capacitor and inductor components. A capacitor that is one tenth of the normal value requires a tolerance of ± 5%, and so on. It is difficult to achieve high-frequency inductors with such strict tolerances. If you believe that the layout inductance is fixed and plan for smaller capacitance values to place the series resonance point in the appropriate position, you will face the same difficulty: you cannot easily control the exact values of capacitance and inductance.
The clock must play continuously and repeatedly without interruption or interval. If the clock stops, the resonant circuit will rotate, suddenly losing control and causing interference as severe as the problem you are trying to alleviate. When the clock restarts, the resonant circuit will take many cycles to catch up and provide zero revenue during this period. Resonant circuits are only useful under continuous stimulation. It is powerless to prevent noise generated by random data events.
The series resonant circuit must be placed within a small portion of the wavelength of any device it protects. Within this limited radius, the extended inductance of the power and ground layers will alter the effective series inductance of the resonant circuit. Therefore, the precise location of the resonant circuit is crucial, and without a complete redesign, the layout cannot be changed. Even worse, resonant elements that provide substantial attenuation for clock noise emitted from one location may not benefit at all and may even exacerbate noise from another location.
Finally, please remember that resonant circuits only attenuate noise at one frequency. It provides almost no benefits on other harmonics of the clock rate. In sine wave based systems such as FM or AM radios, resonant power components can provide truly surprising benefits.