A 340 nA/MHz Low Power FLL-based RC Oscillator with < 1.5 % variation from -40 °C to 175 °C

The architecture of the presented oscillator has a frequency-locked loop with a common-gate opamp and a switched capacitor arrangement emulating a resistor which is driven by a relaxation type VCO (Voltage controlled oscillator). It does not require an external reference, and is self-biased. It can be programmed to generate frequencies from 16 to 24 MHz in steps of 0.5 MHz using a 4-bit control with a low current consumption of 0.34$\mu$A/MHz. It has spread spectrum capability at all frequencies. A PRBS (Pseudo-random binary sequence) generator driven by output frequency/4 is used in the VCO to perturb the VCO control which in turn modulates the frequency for the spread spectrum. The proposed oscillator has a trimmed accuracy of 1.5 % across automotive PVT, using 7 bit trimming. The circuit operates on a 1.6 V supply and has a block size of $0.0161 \ mm^{2}.$