A High-Precision Programmable Voltage Source Based on Vernier PWM

Programmable voltage sources are widely used in the testing system. In this article, a high-precision programmable dc voltage source based on Vernier pulsewidth modulation (PWM) is proposed. In the proposed voltage source, a digital PWM (DPWM) generator generates the PWM signal by utilizing the Vernier principle, which has a much finer step of the duty cycle without greatly increasing the frequency of the clock source. Then, a 1-bit digital-to-analog converter (DAC) converts the PWM signal into an analog signal, which is subsequently filtered by a low-pass filter, forming the output voltage. A prototype of the proposed voltage source is made and verified in this article, which shows a maximum integral nonlinearity (INL) error of 0.85 ppm in the testing.