Analog-to-digital conversion method and analog-to-digital conversion device for temperature sensor
An analog-to-digital conversion method and an A/D conversion device for a temperature sensor are provided. An analog front-end circuit generates an A/D converter input signal positively correlated to a temperature and an A/D converter reference voltage signal negatively correlated to the temperature, and an operation is performed on a ratio of amplitudes of the generated signals to obtain a quantized output value. Since the amplitude of the A/D converter input signal is less than that of the A/D converter reference voltage signal, measurements on other signals is compatible with the measurement on the temperature in a multi-sensor system. A digitized output value is calculated by a digital-assisted readout method to generate a linear output relating to a temperature, thereby improving the accuracy of temperature measurement and reducing complexity of analog circuit design.
1. An analog-to-digital (A/D) conversion method for a temperature sensor, comprising:
generating, by an analog front-end circuit, an A/D converter input signal positively correlated to a temperature and an A/D converter reference voltage signal negatively correlated to the temperature, wherein an amplitude of the A/D converter input signal is less than an amplitude of the A/D converter reference voltage signal; and
calculating a ratio of the amplitude of the A/D converter input signal to the amplitude of the A/D converter reference voltage signal, and performing an operation on the ratio to obtain a quantized output value.
2. The A/D conversion method according to claim 1 , wherein the performing an operation on the ratio to obtain a quantized output value comprises:
performing an amplification operation on the ratio to obtain the quantized output value.
3. The A/D conversion method according to claim 2 , wherein the quantized output value is calculated from the following equation:
Y
=
n
·
Δ
V
BE
V
BE
where Y represents the quantized output value, n represents an amplification factor, ΔV BE represents the amplitude of the A/D converter input signal, and V BE represents the amplitude of the A/D converter reference voltage signal.
4. The A/D conversion method according to claim 3 , wherein after the performing an operation on the ratio to obtain a quantized output value, the method further comprises:
converting the quantized output value to a target value through an operation in a digital domain, and wherein
the target value is linearly correlated to the temperature.
5. The A/D conversion method according to claim 4 , wherein the target value is calculated from the following equation:
μ
=
φ
·
Y
φ
·
Y
+
1
where μ represents the target value, φ represents a coefficient.
6. The A/D conversion method according to claim 4 , wherein after the converting the quantized output value to a target value through an operation in a digital domain, the method further comprises:
performing a linear fitting operation on the target value based on a preset rule to obtain the temperature.
7. An analog-to-digital (A/D) conversion device for a temperature sensor, comprising:
an analog front-end circuit configured to generate an A/D converter input signal positively correlated to a temperature and an A/D converter reference voltage signal negatively correlated to the temperature, wherein an amplitude of the A/D converter input signal is less than an amplitude of the A/D converter reference voltage signal; and
an A/D converter configured to calculate a ratio of the amplitude of the A/D converter input signal to the amplitude of the A/D converter reference voltage signal and perform an operation on the ratio to obtain a quantized output value.
8. The A/D conversion device according to claim 7 , wherein the A/D converter comprises:
a ratio operation circuit configured to perform an amplification operation on the ratio to obtain the quantized output value.
9. The A/D conversion device according to claim 7 , further comprising an N-Metal-Oxide-Semiconductor (NMOS) transistor starting circuit arranged in the analog front-end circuit, wherein a gate of the NMOS transistor starting circuit is connected to an emitter of a bipolar junction transistor (BJT) of the analog front-end circuit, a source of the NMOS transistor starting circuit is connected to a gate of a cascode current mirror, and a drain of the NMOS transistor starting circuit is connected to a positive electrode of a power supply.
10. The A/D conversion device according to claim 7 , wherein the A/D converter is a second-order 1-bit switch capacitor A/D converter based on a Sigma-Delta modulation.