Differential amplifiers are typically used in switch mode power designs. They have a very good common mode rejection ratio over a wide frequency ranges, and two high impedance inputs that are matched. There are two types of products. The first is differential probes. These are typically passive, exhibit relatively good performance, and are low cost, but the CMRR is not as good as a typical amplifier. For example, the common mode rejection ratio is about 10,000:1. However, if customers use a high gain differential amplifier with a matched probe pair, the result is an up to 100,000:1 common mode rejection ratio. In almost all situations, a true differential amplifier will provide the user with the best measurement quality of signals which are not referenced to ground. The output of the differential amplifier is referenced to ground, and the oscilloscope remains safely grounded. Both of the inputs are high impedance, minimizing the effects of capacitive loading on the circuit operation and the measurement. Attenuating probes can be used on both inputs to further isolate the input capacitance from the circuit under test. True differential amplifiers are designed to have large common mode range, enabling measurement of small differential signals relative to large common mode voltages. They also have high CMRR over wide frequency ranges. To maintain high CMRR, both input paths are precisely matched. Any ring or other artifact resulting from the actions of the common mode signal on the input lead parasitics will be nearly identical on both inputs. This allows the differential amplifier to subtract the corruption along with the other common mode components it rejects. Isolators and floating scopes do not have balanced, matched inputs. Therefore the action of the common mode on the parasitics will not be similar on the two inputs and will appear as differential mode at the input. This is one of the key reasons why differential amplifiers perform well in power applications.