Integrating Type DVM Block Diagram – Explanation | New Topic

In this note, we are going to know about Integrating Type DVM Block Diagram and also about its definition, specification, working, advantages, and applications as well. Welcome to Poly Notes Hub, a leading destination for engineering notes.

Author Name: Arun Paul.

What is Integrating Type DVM?

An Integrating Type DVM is a digital voltmeter that converts an analog voltage signal to a digital value by integrating the input voltage over a predetermined time period. It employs an analog integrator circuit and a counter to calculate the time required for voltage conversion, improving accuracy and noise rejection.

Specifications of Integrating Type DVM

• The voltage range is typically from millivolts to several volts (e.g., 0–10V, 0–100V).
• This device has high resolution, usually in microvolts (µV).
• The accuracy is ±0.005% to ±0.05% of the reading.
• The integration time ranges from microseconds to seconds.
• The input impedance is high (typically in Mega-ohms) to minimize loading effect.
• The noise rejection is excellent, due to integration over time.

Integrating Type DVM Block Diagram

Here is the block diagram of integrating type DVM –

The given block diagram represents the functional components of an Integrating Type DVM, which operates based on the dual-slope integration method for voltage measurement. Below is a section-wise explanation:

• Input Stage (Resistors R1​ and R2​): The input voltage is applied to the circuit via a resistor network. These resistors aid in the establishment of optimal voltage levels for integration, as well as the right scaling of input voltage.
• Integrator: The integrator is made up of an operational amplifier with a capacitor in its feedback route. It integrates the input voltage over a set time period, resulting in a linearly increasing or decreasing ramp signal. The slope of this ramp varies in response to the input voltage.
• Comparator: The comparator receives the integrated output and compares it to a reference voltage. When the integrated voltage reaches a predefined threshold, it emits a switching signal, indicating that the integration phase has ended and the de-integration phase begins.
• Pulse Generator: The pulse generator generates clock pulses that regulate the timing of the integration and de-integration operations. It aids in identifying the correct period of the integration, resulting in accurate voltage measurement.
• Digital Frequency Meter: The digital frequency meter measures the time required for de-integration, which is proportional to the input voltage. This count is then translated to a digital voltage reading, which is shown as the final output.

Integrating Type DVM Working Principle

Below we are describing the working of Integrating Type Digital Voltmeter –

An Integrating Type Digital Voltmeter (DVM) works on the Dual Slope Integration Method, which includes two primary phases: integration and de-integration (discharge). During the integration phase, an unknown input voltage is applied to an integrator circuit for a predetermined time. During this time, the integrator produces a linearly increasing ramp signal proportional to the magnitude of the input voltage. The input voltage and the integrator circuit characteristics dictate the slope of this ramp.

Following the integration phase, the system enters the de-integration, or discharge phase. A known reference voltage of opposite polarity is applied to the integrator. This reference voltage (V_ref) causes the integrator’s output to fall at a constant rate, generating a downward ramp. A digital counter measures the time (T₂) it takes for the integrator’s output to return to zero. The input voltage (V_in) is then determined using the ratio of integration and de-integration times, according to the equation:

Because it is known and precisely measured, the digital counter translates the measured time into a matching digital value, which is presented as the final voltage reading. This approach provides great accuracy and strong noise rejection, making it suitable for precision measurements.

Integrating Type DVM Advantages

Here we have listed some advantages of integrating type DVM –

• This type of device accuracy is high.
• This digital voltmeter cancels the AC noise.
• It produces stable reading.
• The operation is unaffected by components.
• It can measure wide range of voltage accurately.

Integrating Type DVM Applications

Here we have listed some applications of integrating type DVM –

• Used for precision voltage measurements in digital multimeter.
• Used in scientific and industrial research.
• Used to accurate voltage measurement in automated testing.
• Used to monitoring and control voltage levels in equipment.
• Used in ECG, EEG machines for precise voltage readings.