Foreword: What is the general understanding of EMG amplifiers by users familiar with EMG amplifiers? The EMG amplifiers we often use have many similarities with other amplifiers in many ways, so let's talk about the differences and advantages and disadvantages of EVB03 voltage amplifiers and charge amplifiers.
Si Cheng He Jing/Photo
<h1>The difference</h1>
Voltage amplifier: Its role is to convert the high impedance of the piezoelectric sensor to a low impedance value and to amplify the weak voltage signal of the piezoelectric sensor. The piezo amplifier is strictly called a transformer because it can make the output voltage larger and also reduce the output voltage to meet the requirements of different circuit voltages.
Charge Amplifier: The EMG Charge Amplifier is a preamplifier whose output voltage is proportional to the amount of input charge. Its advantages are wide frequency band, high sensitivity, high signal-to-noise ratio, simple structure, reliable operation, light weight and so on.
The structure is different
The EVB03 amplifier is a device that increases the signal voltage.
The charge amplifier consists of a charge conversion stage, an adaptation stage, a low-pass filter, a high-pass filter, a terminal amplifier, and a power section.
The principle is different
A voltage amplifier load is a resonant or coupled loop that requires good amplitude-phase characteristics and high selectivity over the frequency range.
The charge amplifier uses a voltage of 15V. The system filters the transformer by AC220V50Hz for step-down rectification, and then regulates the transformer through a regulated power supply.
Features are different
A voltage amplifier is a true analog signal amplifier whose inputs change the amount of analog (such as an audio signal, or a linearly changing DC voltage); there is a distorted signal with amplitude amplification but exactly the same waveform at the output.
The inducers of most charge amplifiers can turn the mechanical amount into a weak charge amount of Q, while the output impedance Ra is extremely high. And this weak charge is converted into a proportional voltage by adapting the load amplifier, so that the high output impedance changes from a high output impedance to a low output impedance.
<h1>Features</h1>
The voltage amplifier converts the high impedance output of the sensor into a low impedance output. In piezoelectric sensors, the EVB03 voltage amplifier can make its output impedance smaller, thereby reducing the weak voltage signal of the piezoelectric sensor.
Voltage amplifiers require high input impedance to match the sensor, so interference immunity is not strong.
Bandwidth of the voltage amplifier. Sensitivity is limited by the capacity of the sensing line, and the output voltage of the charge amplifier is proportional to the amount of input charge, and the signal-to-noise ratio is high
<h1>Amplifier functions and advantages and disadvantages</h1>
Simply put, the EVB03 amplifier amplifies the weak signal provided by the signal source to drive the load normal operation. Since the signal power provided by the signal source is too small to directly drive the load, the EMG amplifier controls the output power of the DC power supply, so that the output power changes with the input signal, and then transmits this changed energy to the load so that the load can work normally. This is basically the action of energy control!
FETs have a common source. Common drain, three kinds of common gates. According to the amplification target, it is divided into voltage amplifier, current amplifier, and power amplifier. In addition, there are single-stage amplification and multi-stage amplification. For a single-tube amplifier composed of a triode, the common-beam stage circuit has inverting voltage amplification and current amplification. Multi-stage amplifiers are commonly used as intermediate stage voltage amplifiers.
Common base amplifiers have noninverting voltage amplification (voltage amplifiers). Mostly used for high-frequency signal amplification. Co-collector has a noninverting current amplification effect (current amplifier). Can be used as a multistage amplifier for input, output, and isolation stages. All three amplifiers, of course, have the effect of power amplification. EMG amplifiers mainly output large voltages and large currents to the load, that is, high power.
If you need more EVB03 amplifier related models, please find Ningbo Sicheng