How does a switched capacitor integrator perform analog integration without using continuous resistors or inductors?
1 Answer
A switched capacitor integrator is an electronic circuit that performs analog integration without using continuous resistors or inductors. Instead, it utilizes a series of switches, capacitors, and operational amplifiers (op-amps) to achieve the integration function. This technique is commonly used in analog signal processing and analog-to-digital converters (ADCs). Here's how it works:
Basic Principle: The switched capacitor integrator leverages the property of capacitors to store and transfer charge. During the integration process, the input signal's voltage is integrated by converting it into a proportional charge across the capacitor.
Switched Capacitor Circuit: The core of the switched capacitor integrator is a configuration of switches and capacitors. The switches are controlled by clock signals. When a switch is closed, the capacitor is effectively connected to a signal source or an operational amplifier; when the switch is open, the capacitor is isolated.
Sampling Phase: In the first phase, known as the "sampling phase," the input signal is connected to the capacitor, and the capacitor charges to the input voltage level.
Hold Phase: In the next phase, called the "hold phase," the switches disconnect the capacitor from the input signal and connect it to the input of the operational amplifier. The capacitor holds the charge acquired during the sampling phase.
Integration: The operational amplifier now acts as a virtual ground, keeping both terminals of the capacitor at the same potential. As a result, the capacitor's voltage integrates over time. The output voltage of the op-amp represents the integrated value of the input signal.
Clocking: The switches and phases are controlled by clock signals to ensure proper sequencing of the operations. The clock frequency determines the integration time and bandwidth of the integrator.
Discharging: After the integration process is complete, a discharge phase may be introduced to reset the capacitor's voltage to a known initial condition, preparing it for the next integration cycle.
Sampling Rate and Accuracy: The accuracy of the switched capacitor integrator depends on factors like the clock frequency, capacitor values, and the resolution of the operational amplifier. Higher clock frequencies can improve accuracy but may also increase power consumption.
Switched capacitor integrators are advantageous because they can achieve high precision and linearity without relying on continuous resistors or inductors, which may have limitations in terms of fabrication and integration with other electronic components. However, they have some limitations as well, such as limited bandwidth and the presence of sampling noise, which can be mitigated through clever design techniques and oversampling.
Basic Principle: The switched capacitor integrator leverages the property of capacitors to store and transfer charge. During the integration process, the input signal's voltage is integrated by converting it into a proportional charge across the capacitor.
Switched Capacitor Circuit: The core of the switched capacitor integrator is a configuration of switches and capacitors. The switches are controlled by clock signals. When a switch is closed, the capacitor is effectively connected to a signal source or an operational amplifier; when the switch is open, the capacitor is isolated.
Sampling Phase: In the first phase, known as the "sampling phase," the input signal is connected to the capacitor, and the capacitor charges to the input voltage level.
Hold Phase: In the next phase, called the "hold phase," the switches disconnect the capacitor from the input signal and connect it to the input of the operational amplifier. The capacitor holds the charge acquired during the sampling phase.
Integration: The operational amplifier now acts as a virtual ground, keeping both terminals of the capacitor at the same potential. As a result, the capacitor's voltage integrates over time. The output voltage of the op-amp represents the integrated value of the input signal.
Clocking: The switches and phases are controlled by clock signals to ensure proper sequencing of the operations. The clock frequency determines the integration time and bandwidth of the integrator.
Discharging: After the integration process is complete, a discharge phase may be introduced to reset the capacitor's voltage to a known initial condition, preparing it for the next integration cycle.
Sampling Rate and Accuracy: The accuracy of the switched capacitor integrator depends on factors like the clock frequency, capacitor values, and the resolution of the operational amplifier. Higher clock frequencies can improve accuracy but may also increase power consumption.
Switched capacitor integrators are advantageous because they can achieve high precision and linearity without relying on continuous resistors or inductors, which may have limitations in terms of fabrication and integration with other electronic components. However, they have some limitations as well, such as limited bandwidth and the presence of sampling noise, which can be mitigated through clever design techniques and oversampling.