When structuring the design, one should consider taking the signal amplification into account. Constructing a signal amplification device requires a good input of ideas for the whole design. In this article, we are going to discuss the steps used in optimizing the signal amplification design of PCB.
Signal amplifier design basics
- A signal amplifier is an electrical circuit with electrical power whereby the electrical power is used to boost the amplitude of a current signal and output a higher amplitude version at its output terminal.
- Signal amplifiers are used in many devices including public address systems, radio frequency transmitters, telephone systems, and many others.
- This signal amplifier is made in very many different ways. Some are made out of bipolar transistors or even thermionic valves.
- An amplifier can be said to be a block with two input terminals and output terminals
Main properties of an amplifier
- Input resistance: This is the resistance seen by a signal source when it is connected to the input of the amplifier whereby the input resistance will be assumed to be a load to the source. In this case in which the load is purely resistive is a special event, which normally will be an impedance.
- Output resistance: This is the resistance developed within the amplifier. This can be determined by measuring the output voltage against the no-load conditions. knowing circuit voltage and load resistance and the voltage reduced throughout the internal resistance under load. The source output resistance can be determined.
- Gain: You can have a current gain within a circuit. It is useful when the need of driving a low impendence arises
How to design a signal amplifier device
Design the PCB board with the help of automated software: The software should be realistic enough to put on paper the type of PCB to be designed according to its size and shape and convert it into a tangible form kind of aboard.
- STEP 1: Find the components or parts to be used.
Depending on the design you want you need to have these parts;
- Power supply:
one toroid transformer with double secondary windings 120 VA max output, 2x 12-18 Volt.
one rectifier module KBU1005
Anti-interference filter for mains supply
3 Amp fuse with socket
100 kOhm resistor to dim the LED
heavy duty power cable
- Connectors: A piece of aluminum to mount the connectors in
- Casing: of any material that may be available
- STEP 2: Size and design of Amplifier
The casing made should fit the size of the amplifier. connectors on the backside of the amplifier casing, mount them into a separate plate of aluminum, and screw the plate onto the inside of the backside of the casing.
- STEP 3: Circuit diagram
The circuit diagrams should be built on a PCB with all points point-to-point soldered on the chip’s leads. Connect the transformer to the secondary coils. Connecting the leads wrongly will lead to a result of a 0 Volt output. When correctly connect should it should show 40 to 50 Volts AC. To find the right configuration you can use an oscilloscope, but it can also be done with a multimeter, set on AC Voltage.
- STEP 4: Prototype the power supply
Connect all the parts with connectors and crocodile clamps and hook them up to an oscilloscope
- STEP 5: Prototype the amplifier
Prototyping amplifiers is a difficult activity. It needs point to point soldering but by the use of a PCB the soldering is done easily
- STEP 6: Volume control, connector, and wires
In this step, you are going to connect the power, ground, and signal on the plate.
In volume control, the middle lead goes to the amps through a resistor. While the other goes to the ground and the remaining is connected to the input.
At the connectors, the connectors are mounted on the PCB board
Connect the potentiometer to the lines into the heat sink. You then mount the amps on the heat sink and connect the wires and cut them short. Use a shrink up to isolate the soldered connections
- STEP 7: Fit the power supply into the case
Connect the power supply wiring system. The toroid transformer should be mounted on the board.
- STEP 8: Test the amplifier design to determine if the process was a success
If the connections were made correctly you will not hear any noise coming out of the amplifier. But when some of the connections were made loosely a soft voice will be heard when the music audio is turned off but won’t be recognized when the music is playing.
Designing an amplifier PCB is a complex process. It is usually performed by automated machines depending on manufacturer choice. Drilling, punching, platting, and testing are the main process in the whole designing process. Ideally, the whole process begins with making a circuit which will make the process appear easier. The next step after making the circuit is laying out traces before drawing any wires.
all those discussed above have to be determined by:
- Supply of the power output- this is obtained by the peak output voltage of the amplifier
- A good sink heat sinks big enough to remove heat that was created for durability
- The stability and components value: one can find the components value and stability by circuit simulation software
- Decoupling capacitors: capacitors of high value increase the bass response and the same time-saving current on the low-frequency output
- Soldering for both smaller and larger components
Materials used for the Amplifier PCB
Most of these materials can be gauged by the relative dielectric constant of their properties. This material range from FR-4 to PTFE (polytetrafluoroethylene) dielectric materials. FR-4 is the best of all the others for the designing of amplifier PCB because of its ability to resist heat.
Operational PCB signal amplifier layout design
- Place a bypass capacitor
An operational amplifier requires a stable input voltage for it to produce the right output signal. A bypass capacitor is placed near the supply pin of the operational amplifier. Its importance is the reduced noise produced while switching the power supply
- Ground plane placement close to inputs pins should be avoided
The stability of the circuit will increase when the ground plane is set correctly. You should avoid placing gourd plates near the amplifier pins. Ground noise defects can heavily affect operational amplifier output.
- Maintain thermal stability
You must have a technique that eliminates the internal thermal heat such as heat sink and vias.
Excess heat damages the amplifier printed circuit board with this the excess heat can be eliminated
- Ensure analog and digital separation
During the design of the PCB amplifiers layout, the operational amplifier should not be near the high-frequency tracks. One can also decide to make an operational amplifier for signal gain -+ of a temperature sensor. It reduces signal transmission and reaction time of digital sensors
Signal amplification design steps
- STEP 1: Select the right sensors
This is the first thing before starting the design. You should be sure of selecting the right sensor to be used in the design. There are many different types of sensors in the technological market that may confuse the right sensor of the choice/design. Despite this measuring is typically not a good criterion when choosing a sensor for the signal amplification device.
Select a sensor capable of measuring around the limits required and which has an excellent sensitivity to detect even a tiny change as it is in the design specification. After carrying out the selection and identification activity of the right sensor of the design of your choice, confirm the output signals and determine up to what certain level it should be amplified before it is processed by the ADC.
A sensor is a device that performs an input function. Common types of these sensors include carbon, microphone, and piezo-electric crystal.
- STEP 2: Ensuring noise immunity
An amplified raw signal the sensors were chosen may have a low amplitude comparing it with the operating voltage of the processing controller and ADC.
- When the signal is fixed and even a slight fluctuation of the voltage of the raw signal is recorded can cause a large deviation of the measured value.
- This is the reason why the analog signal track needs to be protected from any electrical interference. Routing sensitive practices of analog signals must be used.
- Analog track carrying the sensor signal should be well routed rooted and also made very short.
- Frequency is high and power tracks must not be brought near the analog signal and a separate ground plane for analog circuitry should be put into place.
- STEP 3: Best practices of application circuitry design should be followed
The signal processed by ADC should be amplified by a certain magnitude. Here that’s where the need to use an operational amplifier.
- An amplifier that is connected with several resistors can be sued to boost the signal as required. It is also important to consider that the gain is stable.
- Application devices with small signals or high-frequency uniformity are performed to ensure that the most rate of power from the sensor is transferred to the input of the operational amplifier.
- STEP 4: Analog to digital conversion preparation
For data processing to be successful analog signals have to be changed to digital. That’s where the use of an ADC comes into use. There are two different ways in which the ADC can be put into use.
- The first way is the use of a built-in ADC within a microcontroller and the second way is the use of a dedicated ADC chip.
- The advantage of sticking on-the chip is to give access to the microcontroller to read the values from the register instead of an external ADC.
- ADC mostly has a good 24-bit resolution and is fixed up with automatic sampling to provide more accurate readings.
Also, you have to ensure that the ADC has enough bandwidth for checking and sampling the analog signal. This is done by the use of the Nyquist Theorem which describes that the sampling frequency should be with the frequency of the input signal
- STEP 5: Understand signal processing principles
Every device should have a signal amplification purpose.
- Depending on the purpose for which it is designed the amplified signal may be represented by a display that can be seen or changed to an analog output.
- In some of the devices, the amplified signal is constantly measured to a threshold value.
- When one is integrating a signal amplification, it requires a meticulous design approach that can cause problems when you don’t have the right design software
How to specify Amplifier PCB layout
The aspects below are used to specify the amplifier PCB layout.
- Pin connections
- Electrical rings of supply and input voltage.
- Its applications like the single power supply, split power supply, two-way
- Electrical related characteristics like supply voltage and input offset voltage and current, power bandwidth, and provide voltage rejection ration
- There also are class D and AB amplifier types
Amplifier PCB design rules and guidelines
This amplifier design rules and guidelines are split into sections as discussed widely below.
- Board constraint PCB design guidelines
These guidelines are specifically related to the board which incorporates shapes and a few other factors.
Some of these factors include:
- Decision on reference points that are best for the manufacturing process – the reference holes on the board are employed in picking and placing machines. The holes or points should be clear with noninterfering objects
- Allow adequate board is for the circuit – before the designing of the amplifier starts you ought to consider the scale which goes to be used and it should be enough for the activity. The scale determines the whole components that are visiting to be fitted on the board
- Calculate the number of layers to be used within the early stage of the designing of the board, the number of layers that are to be used should be determined. the more the layers the more the space for more tracks.
- Consider the tactic of board mounting – this rule ensures there is enough space available for the mounting activity of the PCB. Different mounting styles have parts of the board that is free from tracks.
- PCB layout design guidelines
These guidelines should be looked into before the planning of circuits. This takes place by looking at the most effective track layouts.
- PCB design guidelines of the planes or layers used
It’s a rule that one can use full planes or layers
- Instances where complete planes are used for amplifiers that completely escort the power rails. This has a plus because it reduces noise while its current capability is enhanced
- Partial planes should be avoided and not be used. This helps in avoiding significant gaps in power planes by keeping the PCB intact. Avoiding the gaps in power planes decreases the changes of board wrapping when the circuit overheats.
- Track design guidelines
This creates enough time for the manufacturer to continue with suitable trade-offs. This is the most effective in designing working tracks.
- Track width to be used should be determined. Choosing the best standard track design should be conducted at the first stages of the amplifier design PCB.
- Determine the pad shapes of the PCB. This shape helps in knowing the number of components that are going to be used when fitting and even soldering.
- Narrow tracks that are too close should not be used because they may cause a short circuit when one of them comes together with another. Also, the utilization of enormous and spaced tracks reduces the number of components that are to be fitted on the PCB causing the issue of the introduction of additional planes.
- Consider the size of the track carrying the current. The thickness of the lines determines the quantity of heat produced when the current goes through them. These rare tracks carry a limited current than thick tracks
Testing quality of the amplifier PCB layout
Testing of quality is done by the use of ATG machines and factored through the following’
- Ability to maintain consistent same dielectric with variations of temperature
- Its ability to be fabricated into circuits with consistent impedance
- Ability to control the type of heat that will be generated by the power amplifier through coefficient thermal expansion and conductivity
- The amount of energy lost as a result of dissipation. The value should be as low as possible to ensure minimal loss of output power and signal again
Characteristics of the amplifier PCB design
Characteristics shown by this PCB amplifier design include:
- High open-loop gain
This is the flexibility of the amplifier to extend the ability of the power signal. This is often measured by the interval between outputs and input ports where there is no feedback in the circuit. When using high open-loop gains many feedback levels are achieved. The use of this helps in achieving the desired performance level.
- High input impedance
This is used at the signal to drop voltage entirely on the amplifier. When the input impedance is low there will be zero voltage across the amplifier thus not receiving a signal. This explains why PCB amplifiers must be designed with low impedance materials. It also prevents loading when an operational amplifier encompasses a low input impedance it will draw an oversized current to it. The design also contributes to noise reduction.
- Low input impedance
When the voltage is dropped the signal is amplified by the operational amplifier. you can also lose signal across the amplifier that is feeding. The amplifier requires an occasional magnitude that will reduce signals that have been amplified across another device.
- Limited bandwidth
During the designing of the amplifier, an acceptable bandwidth that matches the frequency should be the one in use. Narrow bandwidth may lose some signal frequency and when the bandwidth is wide noise may occur.
Uses of signal amplifier PCB
Amplifiers PCB is used in many different applications. They form centralized operations in changing raw analog signals to digital signals. Many of its uses are discussed below widely.
- Amplifier PCB is important in increasing the amplitude of the signal. While during this task it helps in maintaining other aspects such as frequency
- Amplifier PCB is used to change analog signals to digital signals
- They have a high voltage gain and high output resistance. This type of their behavior makes them provide enough output to drive speakers
- Amplifier PCBs which have a content gain between DC and AC are used in oscilloscopes
- Amplifier with high frequency is used in detecting metal fatigue also in ultrasound scanning
- No gain because of their low input resistance. This helps in preventing unwanted signals as it acts as a buffer between the two circuitries
An amplifier PCB is the most important thing in the amplifier. It has components that accept signals and boost its strength. This is done by passing the signal on a transistor that blends it with additional current from a power supply. When designing a signal amplifier, the circuit design of the amplifier has to create and produce its input signal increasingly. the design of the amplifier PCB is the most critical part of good circuit performance. When the PCB layout is badly designed will influence the performance because it will bring up leakage resistance.