What Is a Battery-Powered Amplifier?
Operational amplifier single power supply means that the operational amplifier uses only one type of power supply, such as DC 5V, DC 12V, single power supply, and the output has only one voltage. If the input waveform changes, the output only changes in the positive voltage waveform.
- The dual power supply is composed of a positive power supply and an equal negative power supply, which are usually positive and negative 15 volts, positive and negative 12 volts, and positive and negative 5 volts. The input and output voltages are given as reference grounds. The involved op amps use this dual power supply method, but in some actual production designs, there is no or only a single power supply method, it is necessary to take corresponding solutions. When the single power supply is used, the positive power supply is connected to Vcc and the power ground is connected to the public ground. It is necessary to connect half of the positive voltage Vcc Vcc / 2 as the virtual ground to the non-inverting input of the op amp. Add a resistor VCCVCC / 2. On this basis, we design the corresponding op amp circuit according to the requirements. After the power is connected, the single power supply will work normally. Vcc / 2 can be derived from the positive voltage Vcc in the form of resistance voltage division. Yes, but this may reduce the low frequency characteristics of the op amp.
- Single-supply operational amplifiers are generally biased to ensure that the swing of the output signal is within the range of the power supply. If the input signal of a single power supply system uses ground as a reference, it is actually a reference of one end of the power supply. For example, such an inverting amplifier cannot work normally when the input signal is a positive voltage because the output cannot be lower than the minimum supply voltage. When the input signal is not ground-referenced, the difference between the reference level and ground will be amplified with the signal, unless the reference level appears as a common-mode voltage. Therefore, the input signal must be biased to obtain the desired output voltage. In order to solve this problem, it is naturally thought that the signal adopts the method of AC coupling. However, the use of AC-coupling input and output requires a coupling capacitor, and the presence of the coupling capacitor affects the low-frequency response of the circuit and reduces the bandwidth. When using the non-inverting configuration, the static output of the amplifier will affect the bias voltage of the input through the feedback loop, which is very troublesome to handle.
- Operational amplifiers have four configurations: in-phase forward bias, same reverse bias, reverse forward bias, reverse reverse bias, and their reference voltages
- The following steps can be used to design a single-supply op amp:
- 1) First determine the maximum value of the distortion-free input signal
- 2) Solve b according to the above formula, and then determine which one of the four configuration methods is based on the symbol of b. Then solve the equation to complete the circuit design.
- With the increasing use of battery-powered systems, single-supply operational amplifiers are also increasingly used. Due to the bias problem of single-supply operation, its application is more complicated than dual-supply applications. [1]
- A signal generator is an instrument that generates electrical test signals with the required parameters. According to the signal waveform, it can be divided into four categories: sinusoidal signals, function signals, pulse signals, and random signal generators. The circuit can be constructed by op amps and separate Components or monolithic integrated function generators. Although there are standard products with complete functions, high performance indicators, and expensive prices in the market, many of its functions have been idle in actual teaching and training, resulting in a serious waste of resources. Most general operational amplifiers use dual power supplies, which require higher power supply conditions.
- Using LM324 as the core device, using single power supply mode, through the idea of "sine wave square wave triangle wave", where the sine wave is generated by the RC bridge oscillation circuit, and then the square wave is generated by the zero-crossing comparator, and then RC integration The circuit generates a triangle wave. This solution uses a single power supply. The requirements for the power supply are not high. It can reduce power consumption and cost. The circuit structure is simple, and it can generate sine wave, square wave and triangle wave signals with good performance. The amplitude and frequency are stable and Wide adjustment range facilitates debugging.
- Single-supply waveform generator circuit diagram
- A single power supply is used to power the LM324, and the four operational amplifiers in the LM324 and the peripheral circuits are used to generate signals together. One of the operational amplifiers and peripheral components form an RC bridge-type oscillation circuit to generate a sine wave signal. A voltage follower composed of one of the operational amplifiers is used to ensure the stable output of the sine wave signal, and then the output sine wave signal is connected to the other operation. The non-inverting terminal of the amplifier input and the inverting terminal are connected to the midpoint potential to form a zero-crossing comparator to output a square wave signal. The output square wave signal is then used to output a triangular wave signal through an RC integration circuit composed of the next operational amplifier and peripheral components. In this way, only one LM324 chip and some simple peripheral circuits are needed to achieve sine wave signals, square wave signals and triangle wave signals with stable amplitude and frequency and wide adjustment range, so as to achieve the effect of "three birds with one stone". [2]