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By David Vye, Senior Product Marketing Manager, AWR, Cadence When designing multi-octave high-power amplifiers, it is a challenge to achieve both broadband gain and power matching using a combination of lumped and distributed techniques. One approach...(read more)

Hey, is it suitable to post here? I wanted a small yet robust amp for practicing while I travel. I wanted something that would fit in my pocket yet still be loud enough to hear.

Presented here is a amplifier based upon the LM386 Audio Amplifier.

There is a standard circuit in the data sheet that is an excellent place to start.

Materials needed:
1 - HM359 project box
1 - 668-1237 speaker
1 - BS6I battery conn
1 - CP1-3515 stereo jack
1 - SC1316 stereo jack
2 - 450-1742 knob
1 - 679-1856 switch
1- 3mm LED
1 - 10 ohm 1/4W resistor
1 - 10uF ceramic cap
1 - .05 uF ceramic cap
1 - 420 uF electrolytic cap
1 - 8 ohm resistor
2 - 51AADB24 10K pot
1 - HM1252 circuit board
1 - LM386N-4 amplifier

Wire and Solder
Step 1: Prep the enclosure

Careful planning is required the first time you free build a circuit. The circuit board has solder pads but not traces. You will have to use thin wire to make the connections for the circuit to work.

Begin by laying out the components on the circuit board that will need to pass through the enclosure. This enclosure has a removable top panel which will be used for the volume, gain and 1/4 inch stereo jack.

Space is limited to check for fit before drilling.

All drilling of the plastic should be done with a step drill bit. This will make the cleanest holes without breaking the plastic.

Lay out the pots a few spaces back but still in line with the desired position. mark the center of each pot shaft then drill with a step drill tot he tightest fitting hole size. Make a center mark between the pot holes then drill for the stereo jack

On the inside of the top cover position and mark where the speaker will go.

Make a template on grid paper the same size as the speaker.

Tape the template to the inside of the cover as shown then use a step bit to drill holes on the center of every square in the grid. This will form the speaker grille. clean up the holes.

Step 2: place the major components

Solder the pots to the circuit board as shown. then place the stereo jack(note in order to get the final fit I had to trim and modify the stereo jack housing a little)

Next, position and solder the switch on the circuit board and mark a space on the top cover that will need to be cut for the switch opening. Use a small file to cut the opening.

Use a sharp knife to bevel the edges of the switch hole to allow for easier operation.

Drill a hole in the side of the upper case for the headphone jack and fasten it in place. ( I had to recess the hole a bit for the retaining nut to grab)

Step 3: Build the circuit

The speaker is held in place by using 2 small brackets that come with the serial cable connector hood. ( I had a bunch around that would never be used)

Refer the the circuit shown from the datasheet and the datasheet for the LM386. The basic circuit only has the volume control while the datasheet shows how to add a gain control across pins 1 and 8 of the amplifier.

The speaker is wired in series with the headphone jack. The headphone jack has internal switches that shut the speaker off when the phones are plugged in.

I chose to use a chip socket for the amplifier which make prototyping easier since you do not have to worry about solder heating as much.

Carefully lay the circuit out on the board and begin wiring components together. I added a second pot and cap in series between pins 1 and 8 of the amp to be able to manually set the gain in addition to volume.

Check you connections with a multimeter before adding the amplifier.

I chose to add a LED indicator for power. This was done by using one side of switch contacts from the battery. The LED is in series with a 220 ohm resistor.

Assemble the case and insert the battery.

Step 4: Final notes

If the speaker is noisy while the headphones work normally, try reversing the speaker connections. If it does not correct the issue, connect a 8 ohm resistor across the speaker contacts.

You may have to place an insulating layer between the speaker and the place where the stereo jack comes through to prevent contact. This will be noted by a loud buzz.

You may have to add some foam in the battery compartment to stop the battery from banging around.

For reference, I've also read an article about amplifiers: http://www.apogeeweb.net/article/60.html

Thanks for reading!
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General-purpose Photoelectric Sensor for High Quality and Reliable Detection(E3S)

(E3S-A)

The Advanced Fiber Amplifier Units That Handles On-site Needs(E3NX-FA)

A CMOS Laser Sensor That's　Optimum for Simple Measurements(ZX1)

Stable Detection of Level Differences in the Order of 0.1 mm(ZX0)

Smart Fiber Amplifier Units with White LEDs. High Color Discrimination Capability with the Same Easy Operation as Previous Fiber Amplifier Units. Existing General-purpose Fiber Units Can Be Connected.(E3NX-CA)

2-channel Amplifier reduces installation space by half. Downsized Equipment and Control Panels(E3NX-MA)

IoT Status Monitoring Amplifiers for General-purpose Analog Outputs Are Connectable to Various Sensors(E9NC-AA / VA)

The present invention aims to simulate a response more similar to a actual machine while inhibiting load increase in analog operation. Program configuration of the present invention is a component of a simulation program for circuit design, which is executed by a computer. The computer includes an operation portion, a storage portion, a manipulation portion, and a display portion, so that the computer exerts a function of a circuit design simulator, and as a macro model of an operational amplifier for use in the circuit design simulator, enabling the computer to act by simulating a response of the operational amplifier on the circuit design simulator. The macro model of the operational amplifier includes a control portion (LMT1) for generating output exception in the event of input exception or power supply exception of the operational amplifier.

An implantable medical device lead having a flow measurement sensor mounted thereon is provided with a capsule mounted proximate to the sensor. The capsule is used to house electrical circuitry corresponding to the sensor in order to prevent impedance on conductors of the lead, which gradually decreases over chronic periods, from directly affecting signal transmission between the sensor and the electrical circuitry. The electrical circuitry includes a charge amplifier used for processing signals from the sensor. In some cases, the amplifier can be initially calibrated and periodically tuned so as to have consistent functioning with the sensor over chronic periods.

An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

A circuit includes first and second transconductance stages that generate first and second currents, respectively, in response to an input signal. A current combiner circuit selectively couples the first current to a first output, selectively couples the second current to the first output, selectively couples the first current to a second output, and selectively couples the second current to the second output. In response to the first current being coupled to both the first and second outputs, the current combiner circuit couples the second current to both the first and second outputs. In response to the first current being decoupled from the second output, the current combiner circuit decouples the second current from both the first and second outputs. In response to the first current being decoupled from the first output, the current combiner circuit decouples the second current from both the first and second outputs.

A mechanical capstan amplifier. The mechanical capstan amplifier (60) having a first tensioner (64) with a first actuating rod (72) extending therefrom. The first tensioner (64) is configured to rotate the first actuating rod (72). The amplifier (60) also includes a drive motor (62) having a drive rod (78) extending therefrom. The drive motor (62) is configured to rotate the drive rod (78). A first cord (66), extending between the first actuating rod (72) and a first load to be moved also extends at least partially around the drive rod (78). Actuation of the first tensioner (64) causes the first cord (66) to tighten around the drive rod (78) and moves the load.

The present disclosure provides methods and devices for testing a connection between speakers and a power amplifier. The disclosed methods and devices solve a problem that, upon a connection test for a power amplifier which has a booster power source, when a midpoint potential of the power amplifier and the voltage of the speaker connection terminal are compared, and it is determined that short-circuiting occurs on a ground side when the potential of the speaker connection terminal is lower than the midpoint potential, a wrong test is conducted if a midpoint potential is higher than a battery voltage.

An amplifier receives an amplitude signal of a polar modulated signal at a base terminal of a transistor and receives a phase modulated carrier signal of the polar modulated signal at the base terminal of the transistor. The amplifier combines the amplitude signal and the phase modulated signal to produce a full complex waveform at a collector terminal of the transistor.

Provided is a method of generating a driving signal for driving a dual mode supply modulator for a power amplifier. The method includes obtaining an envelope of a complex baseband signal to be transmitted, comparing the envelope of the complex signal with a preset threshold value, when a current envelope of the complex signal is the preset threshold value or greater or when there is a result having the preset threshold value or greater in previous N comparisons, outputting a digital board output signal configured with a first logic level through a digital-to-analog converter; and when the current envelope of the complex signal is smaller than the preset threshold value and when there is no result having the preset threshold value or greater in the previous N comparisons, outputting a digital board output signal configured with a second logic level through the digital-to-analog converter.

A modulation apparatus for a class D switching amplifier is capable of reducing power consumption of an Electro-Migration Interface (EMI) of an output end and a gate driver end in a zero input signal. The modulation apparatus for a class D switching amplifier includes a control unit for detecting and outputting a control signal which is a common signal component of a first modulation signal modulated by using a first input signal and a second modulation signal modulated by using a second input signal; and is characterized by feedback of a first output signal, a second output signal and a common output signal outputted by using the first modulation signal, the second modulation signal and the control signal through an input of the modulation apparatus.

An amplifier circuit includes an input terminal and an output terminal. A current sinking transistor includes a first conduction terminal coupled to the output terminal and a second conduction terminal coupled to a reference supply node. A voltage sensing circuit has a first input coupled to the input terminal and a second input coupled to the output terminal. An output of the voltage sensing circuit is coupled to the control terminal of the current sinking transistor. The voltage sensing circuit functions to sense a rise in the voltage at the output terminal which exceeds the voltage at the input terminal, and respond thereto by activating the current sinking transistor.

An amplifying structure includes a main amplifier configured to amplify a first signal; and a peak amplifier configured to amplify a second signal, each of the main amplifier and the peak amplifier including, respectively, a hybrid power device, the hybrid power device including, a first power transistor die configured to amplify signals of a first frequency, and a second power transistor die configured to amplify signals of a second frequency different than the first frequency.

A power converter with positive and negative supply rail outputs for feeding a single ended class D amplifier, the converter comprising a transformer arrangement, a supply pump reduction arrangement connected between the secondary windings and the positive and negative supply rail outputs, and a boost drive mode switching arrangement. A controller is adapted to control the power converter in a negate drive mode and a boost drive mode, wherein the output voltage in the boost mode is increased by means of the transformer and the boost drive mode switching arrangement. The output voltages on the positive and negative rails can be generated at two different output voltage levels without changing the duty cycle or dead time of the control signals.

An input receiver circuit including a single-to-differential amplifier and a semiconductor device including the input receiver circuit are disclosed. The input receiver circuit includes a first stage amplifier unit and a second stage amplifier unit. The first stage amplifier unit amplifies a single input signal in a single-to-differential mode to generate a differential output signal, without using a reference voltage. The second stage amplifier unit amplifies the differential output signal in a differential-to-single mode to generate a single output signal.

A TIA circuit and method are provided that merge the automatic gain control function with the bandwidth adjustment function to allow the TIA circuit to operate over a wide dynamic range at multiple data rates. The TIA circuit has an effective resistance that is adjustable for adjusting the gain and the bandwidth of the TIA circuit. The mechanism of the TIA circuit that is used to adjust the effective resistance, and hence the gain and bandwidth of the TIA circuit, is temperature independent, and as such, the performance of the TIA circuit is not affected by temperature variations.

An amplifier includes a first input terminal, a second input terminal, a TIA, and a compensation circuit. The TIA includes a first transistor, a second transistor, a first current source connected to the first input terminal and an emitter of the first transistor, a second current source connected to the second input terminal and an emitter of the second transistor, a first load resistor connected to a collector of the first transistor, and a second load resistor connected to a collector of the second transistor. A bias voltage is supplied to bases of the first and second transistors, the compensation circuit adjusts a first load current and a second load current based on voltage signals, and the TIA outputs the voltage signals based on collector voltages of the first and second transistors.

Split amplifiers with configurable gain and linearization circuitry are disclosed. In an exemplary design, an apparatus includes first and second amplifier circuits and a linearization circuit, which may be part of an amplifier. The first and second amplifier circuits are coupled in parallel and to an amplifier input. The linearization circuit is also coupled to the amplifier input. The first and second amplifier circuits are enabled in a high-gain mode. One of the first and second amplifier circuits is enabled in a low-gain mode. The linearization circuit is enabled in the second mode and disabled in the first mode. The amplifier is split into multiple sections. Each section includes an amplifier circuit and is a fraction of the amplifier. High linearly may be obtained using one amplifier circuit and the linearization circuit in the low-gain mode.

Embodiments include systems and methods for accurately controlling gain of a high-speed variable-gain amplifier (VGA) without adversely impacting bandwidth performance. Embodiments include a VGA with a variable resistor, for which resistance is a function of a control level. A gain calibration system controls the control level by using a gain control feedback subsystem to sample outputs of a duplicate VGA, which includes a duplicate variable resistor. The sampled duplicate outputs are compared to a target gain generated by a reference generator. The control level can be fed back to control the gain of the duplicate VGA until the target gain is reached. The control level can also be fed to the actual VGA to control its gain. By performing gain control on the duplicate VGA without interfering with the output signal path of the actual VGA, the actual VGA's gain can be accurately controlled without impacting its bandwidth.

Exemplary embodiments are directed to operating a multi-stage amplifier with low-voltage supply voltages. A multi-stage amplifier may include a first path of an amplifier output stage configured to convey an output signal if a first supply voltage is greater than a threshold voltage. The multi-stage amplifier may also include a second path of the amplifier output stage configured to convey the output signal if the first supply voltage is less than or equal to the threshold voltage.

A variable gain amplifier (100) includes a transistor (110), an FB impedance section (120), a source impedance section (130), a drain impedance section (140), a gain controller (150), and a frequency characteristic controller (160). The gain controller (150) varies impedance of one of the FB impedance section (140), the source impedance section (130), and the drain impedance section (140), and outputs a gain control signal. The frequency characteristic controller (160) varies the impedance of different impedance section, based on the gain control signal.

A microwave semiconductor amplifier includes a semiconductor amplifier element, an input matching circuit and an output matching circuit. The semiconductor amplifying element includes an input electrode and an output electrode and has a capacitive output impedance. The input matching circuit is connected to the input electrode. The output matching circuit includes a bonding wire and a first transmission line. The bonding wire includes first and second end portions. The first end portion is connected to the output electrode. The second end portion is connected to one end portion of the first transmission line. A fundamental impedance and a second harmonic impedance seen toward the external load change toward the one end portion. The second harmonic impedance at the one end portion has an inductive reactance. The output matching circuit matches the capacitive output impedance of the semiconductor amplifying element to the fundamental impedance of the external load.

A tunable wide band driver amplifier is disclosed. In an exemplary embodiment, an apparatus includes a first band selection circuit selectively connected between an output terminal of an amplifier and a circuit ground. The first band selection circuit configured to adjust an amplification band from a first frequency band to a second frequency band. The apparatus also includes a first harmonic reduction circuit selectively connected between the first band selection circuit and the circuit ground and configured to reduce 2nd harmonic frequencies associated with the first frequency band when the amplification band is set to the first frequency band.

An apparatus is described that includes an audio power amplifier having an input and an output. An alternating-current to direct-current power converter is coupled to the audio power amplifier in a single package to supply power to the audio power amplifier.

Disclosed is a technique for reducing noise superimposed on an output signal while keeping loop gain constant without increasing the circuit scale and without changing the transfer function of the amplifier apparatus (frequency characteristics of gain and phase). According to the technique, there are included a power-supply voltage control unit 7 for detecting the amplitude level S9 of an input audio signal S1 and outputting power with a voltage value indicated by target set voltage value information Vs corresponding to this amplitude level S9, and a PWM modulation unit 2 including a PWM converter 23 for converting the pulse width of the input audio signal S1 and a correction unit for correcting the signal modulated by the PWM converter 23. The PWM modulation unit 2 corrects the pulse width of a PWM signal S5 modulated by the PWM converter 23 so that the correction unit will cancel out a change in amplification gain of a power amplification unit 4 according to the target set voltage value information Vs.

A pop-free single-ended output class-D amplifier includes: an input signal generator for generating an input signal; a power supply for supplying input power; a reference voltage generator for generating a reference voltage; a gain-adjustable stage for generating an amplified signal according to the reference voltage and adjusting a gain of the single-ended output class-D amplifier; a pulse width modulation module for outputting a pulse width modulation signal according to the reference voltage, the amplified signal, and the input power; a low-pass filter for low-pass filtering the pulse width modulation signal to generate an output voltage; and a logic controller for generating at least one control signal to control the reference voltage generator, the gain-adjustable stage, and the pulse width modulation module according to the input power, the reference voltage, and the pulse width modulation signal.

An electronic circuit, including, a power amplifier adapted to amplify an RF signal and provide it as output from the integrated circuit; a power source that is adapted to provide an unregulated voltage to the power amplifier; a regulator adapted to provide a regulated bias voltage; a subtracter that is adapted to accept a voltage proportional to the unregulated voltage and subtract it from the bias voltage to provide a reference voltage to the power amplifier; wherein the power amplifier is adapted to use the reference voltage to adjust the output from the power amplifier so that it will provide a stable power output.

Differential amplifier circuits for LDMOS-based amplifiers are disclosed. The differential amplifier circuits comprise a high resistivity substrate and separate DC and AC ground connections. Such amplifier circuits may not require thru-substrate vias for ground connection.

Differential power amplifier circuitry includes a differential transistor pair, an input transformer, and biasing circuitry. The base contact of each transistor in the differential transistor pair may be coupled to the input transformer through a coupling capacitor. The coupling capacitors may be designed to resonate with the input transformer about a desired frequency range, thereby passing desirable signals to the differential transistor pair while blocking undesirable signals. The biasing circuitry may include a pair of emitter follower transistors, each coupled at the emitter to the base contact of each one of the transistors in the differential transistor pair and adapted to bias the differential transistor pair to maximize efficiency and stability.

An amplifier circuit amplifies a signal for wireless transmission. A feedback circuit, including a capacitor, is coupled to the amplifier circuit. Components of the feedback circuit are selected based on a feedback factor such that an input impedance to the amplifier circuit has a same impedance characteristic as a feedback circuit impedance of the feedback circuit.

A semiconductor package device comprises a radio frequency power transistor having an output port operably coupled to a single de-coupling capacitance located within the semiconductor package device. The single de-coupling capacitance is arranged to provide both high frequency decoupling and low frequency decoupling of signals output from the radio frequency power transistor.

A power amplifier module includes a power amplifier including a GaAs bipolar transistor having a collector, a base abutting the collector, and an emitter, the collector having a doping concentration of at least about 3×1016 cm−3 at a junction with the base, the collector also having at least a first grading in which doping concentration increases away from the base; and an RF transmission line driven by the power amplifier, the RF transmission line including a conductive layer and finish plating on the conductive layer, the finish plating including a gold layer, a palladium layer proximate the gold layer, and a diffusion barrier layer proximate the palladium layer, the diffusion barrier layer including nickel and having a thickness that is less than about the skin depth of nickel at 0.9 GHz. Other embodiments of the module are provided along with related methods and components thereof.

A power amplifier includes: first and second bias terminals to which bias voltages are respectively supplied; a first transistor having a first control terminal connected to the first bias terminal, a first terminal that is grounded, and a second terminal; a second transistor having a second control terminal connected to the second bias terminal, a third terminal connected to the second terminal, and a fourth terminal; a capacitor connected between the second control terminal and a grounding point; and a variable resistor connected in series with the capacitor, between the second control terminal and the grounding point.

Systems and methods are provided for generating an amplitude modulation signal to a switchmode power amplifier. A DC to DC switch is configured to receive a DC input voltage and to provide a DC output voltage. A low dropout regulator is configured to provide the amplitude modulation signal according to a modulation control signal received by the low dropout regulator. A control circuit is configured to establish a nominal operating power level for the power amplifier via the amplitude modulation signal and to maintain a minimum voltage difference between the DC output voltage and the low dropout regulator output. A modulator control circuit is configured to provide the modulation control signal to the low dropout regulator. The modulator control circuit provides the transition from a high amplitude to a low amplitude and a transition from the low amplitude to the high amplitude at configurable first and second slopes, respectively.

An amplifier includes a signal processing circuit configured to generate an orthogonal signal orthogonal to an input signal; a first D/A converter configured to convert the orthogonal signal into a first analog signal; a second D/A converter configured to convert the input signal into a second analog signal; and an analog computing circuit configured to generate a constant envelope signal based on the first analog signal from the first D/A converter and the second analog signal from the second D/A converter.

An apparatus for amplifying power is provided. The apparatus includes a supply modulator for generating a supply voltage based on an amplitude component of a transmission signal, and a power amplify module for amplifying power of the transmission signal using the supply voltage, wherein the power amplify module includes a first power amplifier and a second power amplifier, and when an output power of the transmission signal is greater than a reference power, the first power amplifier amplifies the power of the transmission signal using the supply voltage, and when the output power of the transmission signal is equal to or less than the reference power, the second power amplifier amplifies the power of the transmission signal using the supply voltage.

A force amplifier has a guide track, a non-locking screw threadedly engaging the track to spirally move in response to an axial input force applied to the proximal end of the non-locking screw. The force amplifier includes a compliant component coupled to the non-locking screw by one end and to a self-locking screw by the other end. The compliant component is configured to transmit a torque generated by the non-locking screw to the self-locking screw, which is actuated to move spirally along the track while generating an axial output force greater than the input force.

An amplifier system has an amplifier for amplifying a plurality of input signals from a plurality of different channels, and a plurality of demodulators each operatively coupled with the amplifier for receiving amplified input signals from the amplifier. Each demodulator is configured to demodulate a single amplified input channel signal from a single channel of the plurality of different channels. The system thus also has a plurality of filters, coupled with each of the demodulators, for mitigating the noise.