Low Noise Crystal Oscillator (CLN7FF)
低噪声晶体振荡器 (TSMC 7nmFF)
· Crystal Oscillator pad macro that supports industry standard crystals
· Uses standard CMOS transistors
· Crystal Oscillation Mode: Fundamental
· Power down option for IDDQ testing
· Oscillator by-pass mode option for logic testing
· Self-contained ESD protection structure
High end consumer and professional applications require crystals with a minimum number of external components. These applications typically operate under severe noise environment of large digital video processing chips. A standard crystal oscillator pad provided in commodity libraries induces high noise and jitter. Analog Bits has developed a unique low noise Crystal Oscillator macro based on a proprietary architecture that is in volume production in several high end graphics and multi-media applications. This differentiated architecture has earned outstanding reviews on high volume production boards.
Typical Usage and Block Diagram
Figure 1 shows the block diagram of the Crystal Oscillator Pad. The macro has a power down control bit that allows to enable a low current state for IDDQ testing. The macro has the inherent capability of bypassing the crystal oscillator circuit by directly feeding the XTAL_IN pin from an external clock generator. In that mode the external clock applied on XTAL_IN pin will go directly to the output (XOUT) of the crystal oscillator macro without any modification. The input threshold will be close to VDDA/2 in this bypassed mode.
Figure 1: Block Diagram
A LOCK signal is provided to indicate a good crystal frequency is available. It goes high after it has counted a preset number of cycles with ENABLE high and PD low, and then it stays high until the next disable or powerdown.
Oscillator Gain Control Pin Settings
Deliverables and EDA Design Views