Suitable for PVT digital calibration method for the medium -shaped voltage -controlled oscillator in the modulus converter

Abstract

A PVT digital calibration method suitable for a ring voltage-controlled oscillator in an analog-to-digital converter. Two sub-voltage-controlled oscillators are embedded in the Delta-Sigma analog-to-digital converter loop as quantizers, and their minimum control values ​​are preset respectively. Voltage and maximum control voltage, the corresponding minimum output frequency and maximum output frequency are obtained by calculation, and the gain and free oscillation frequency of the main VCO are obtained and compared with the standard value. When there is a deviation, the corresponding calibration voltage is generated in real time and checked The sub VCO is tuned until the gain and free oscillation frequency of the output main VCO are consistent with the design values, and the corresponding calibration control voltage is output to calibrate the main VCO. The invention adopts two-point calibration, simplifies the voltage-frequency conversion curve model and has an error of 10% with the real curve model, and has a high degree of approximation while ensuring the integrity of the calibration.

Description

technical field [0001] The invention relates to a technology in the field of ring voltage-controlled oscillators, in particular to a process angle, power supply voltage, temperature (PVT, Process Voltage Temperature) digital calibration method of a ring voltage-controlled oscillator in an analog-to-digital converter . Background technique [0002] Ring VCO is used as a quantizer unit in Delta-Sigma analog-to-digital converters, and its voltage-to-frequency conversion characteristics vary with process angle, power supply voltage, and temperature, causing loop stability and system performance deterioration. The development of modern complementary metal-oxide-semiconductor (CMOS) processes is accompanied by a decrease in power supply voltage, resulting in a decrease in resolution in the voltage domain, which makes it more difficult to design high-performance analog-to-digital converters in the voltage domain. The reduction of transistor feature size can bring about an increase...

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Problems solved by technology

The following two methods are usually used: PVT is calibrated separately, but the calibration of the three variables has high performance requirements for the circuit that realizes voltage and temperature control and requires additional voltage margins. At the same time, it introduces problems of chip area and power consumption, which is difficult Adapt to chip design under low voltage; digital calibration of delay change correlation coefficient, through establishing a benchmark model of delay change with the environment, improve the accuracy of the model through multiple measurements, and calibrate the ring oscillator based on the model, but due to The error of the benchmark model requires high precision and a large amount of calculation. The delay introduced by the digital calibration module used cannot be avoided, and it is difficult to achieve calibration when the tuning frequency range is large.

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