常见的电源类型

Basic types of power supplies based on different design principles:

Linear power supplies

Linear regulated power supplies provide highly constant output voltage, low ripple and noise and fast regulation, even with high line and load transients. They produce significantly less electromagnetic interference than switchedmode power supplies. A conventional mains transformer isolates the power-line from the secondary circuits (output stages). It is followed by a rectifier that supplies the unregulated voltage to a series actuator. Capacitors at the input and output of the regulator circuit serve as buffers and decrease the ripple.

A high precision reference voltage controls the analog output amplifier. This amplifier is generally fast and allows very short recovery times for load changes.

R&S Essentials linear power supplies: R&S®NGA100, R&S®NGL200, R&S®NGM200, R&S®NGU201/401.

Switched-mode power supplies (SMPS)

SMPS, e.g. R&S®NGP800, have much higher efficiency than linear regulated power supplies. In a first step, the line voltage is rectified. Due to the high input voltage, buffer capacitors with a small capacitance can be used. In a second step, the DC voltage to be converted is chopped at a high frequency.

This takes place in the switching transistor and requires only comparatively tiny and light ferrite chokes or transformers with low losses. The switching transistor is switched fully on and off, hence switching losses are low. The output voltage is usually regulated by changing the duty cycle of the switching transistor. A rectifier and low-pass filter improve the output quality.

Mixed architecture power supplies

Different combinations of the above basic designs are in use. For example, the R&S®NGE100B power supplies use a mains transformer at the input, followed by a rectifier and switched-mode circuitry to regulate the output voltage, providing high efficiency. A linear stage reduces unwanted signal components at the output. Another example for mixed achitecture is the R&S®HMP2000/4000.

直流电源的象限

如果电流流入正电压端子，电源会变成电子负载。电源不会供电，而是会吸收电能。可以用作源端和吸收端的电源能够模拟电池或负载，此类电源被称为 双象限（或四象限）电源。罗德与施瓦茨 提供双象限或四象限架构。电源可自动从源模式切换至吸收模式。外部应用电压超过设置的标称电压时，电流会流入电源，电流读数显示为负。

可以使用笛卡尔坐标系详细定义电源架构。四个象限显示正负电压和电流的所有组合。下图显示了一个坐标系，其中纵轴表示电压，横轴表示电流。

如上所述，标准电源通常只会生成诸如 0 V 至 20 V 的正电压（即电源在第一象限工作）。如果电源无需切换外部接线即可在输出端提供正电压或负电压，则此类电源为双极电源并在第一象限和第三象限工作，例如能够提供 –20 V 至 +20 V 的电压。此类电源可用于针对跨 0 V 的双极电压测试半导体的行为特性。

在第一象限和第三象限工作的电源通常还提供吸收功能以用于正负电压和电流。此类电源可在所有四个象限工作，并被称为源测量单元 (SMU)。在第一象限和第三象限中，电流从电压端子流出，电源处于供电模式。在第二象限和第四象限中，电流流入电压端子，电源在吸收电能。

信道具有相同的电压范围

大部分罗德与施瓦茨电源的所有信道均具有相同的电压范围。因此，您可以为特定应用选择任意信道。每个信道均可用作独立电源。

纹波和噪声

复杂的高级电子电路对电源线的电压变化非常敏感。为了尽量减少为被测设备 (DUT) 供电时的干扰，电源必须提供非常稳定的输出电压和电流。理想情况下，输出端应无电压变化。实际情况下，有两种变化会影响电路或设备：周期性变化（纹波）和随机变化（噪声），二者也被称为周期和随机偏差 (PaRD)。线性电源的高频纹波远小于开关电源。

专业型电源和部分基本型电源（例如 R&S®NGA100）通过线性稳压实现非常低的残余纹波和噪声。

输出级采用线性设计，能够为复杂半导体等敏感设计提供低干扰电压。低纹波和噪声也非常适合开发功率放大器和 MMIC。

可变输出阻抗

专业型电源的输出支持多种配置。例如，可以设置输出阻抗等参数、接通延迟和不同的触发模式。电源应尽量具备低输出阻抗以避免对被测设备的负载影响。但是，某些应用需要以可控方式模拟电池，或者模拟电池放电时内部阻抗的增加情况。R&S®NGL200、R&S®NGM200和 R&S®NGU201电源具备可调节输出阻抗，适用于这些应用。