An electrical parameter measurement device, comprising: a voltage test input terminal operatively coupled to voltage measurement circuitry of the electrical parameter measurement device; a common input terminal operatively coupled to the voltage measurement circuitry of the electrical parameter measurement device; and reference signal circuitry, comprising: a common mode reference voltage source which, in operation, generates an alternating current, AC, reference voltage having a reference frequency, wherein the common mode reference voltage source is electrically coupled to the common input terminal; detection circuitry that, in operation, detects a first signal present at the voltage test input terminal; and detects a second signal present at the common input terminal; and processing circuitry that, in operation, receives the first and second signals from the detection circuitry; processes the first and second signals; and determines at least one electrical characteristic of a device under test that is electrically coupled to the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second signals, characterized in that, in operation, the processing circuitry compares a phase of the first signal to a phase of the second signal to determine a measure of impedance of the device under test. a voltage test input terminal operatively coupled to voltage measurement circuitry of the electrical parameter measurement device; a common input terminal operatively coupled to the voltage measurement circuitry of the electrical parameter measurement device; and reference signal circuitry, comprising: a common mode reference voltage source which, in operation, generates an alternating current, AC, reference voltage having a reference frequency, wherein the common mode reference voltage source is electrically coupled to the common input terminal; detection circuitry that, in operation, detects a first signal present at the voltage test input terminal; and detects a second signal present at the common input terminal; and processing circuitry that, in operation, receives the first and second signals from the detection circuitry; processes the first and second signals; and determines at least one electrical characteristic of a device under test that is electrically coupled to the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second signals, characterized in that, in operation, the processing circuitry compares a phase of the first signal to a phase of the second signal to determine a measure of impedance of the device under test. a common mode reference voltage source which, in operation, generates an alternating current, AC, reference voltage having a reference frequency, wherein the common mode reference voltage source is electrically coupled to the common input terminal; detection circuitry that, in operation, detects a first signal present at the voltage test input terminal; and detects a second signal present at the common input terminal; and detects a first signal present at the voltage test input terminal; and detects a second signal present at the common input terminal; and processing circuitry that, in operation, receives the first and second signals from the detection circuitry; processes the first and second signals; and determines at least one electrical characteristic of a device under test that is electrically coupled to the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second signals, characterized in that, in operation, the processing circuitry compares a phase of the first signal to a phase of the second signal to determine a measure of impedance of the device under test. receives the first and second signals from the detection circuitry; processes the first and second signals; and determines at least one electrical characteristic of a device under test that is electrically coupled to the voltage test input terminal and the common input terminal based at least in part on the processing of the first and second signals, characterized in that, in operation, the processing circuitry compares a phase of the first signal to a phase of the second signal to determine a measure of impedance of the device under test.