Phase Splitter : Circuit, Working, Types, Advantages & Its Applications

A phase splitter or phase inverter refers to the polarity of the current and is simply made by changing different kinds of amplifiers (or) optimizing a transformer to efficiently split currents. These are widely used in the music instrument & manufacturing industries for controlling power output. To manufacture this, one of the less complicated methods is to utilize a transformer. This article provides brief information on a phase splitter, working, types, and its applications.

What is a Phase Splitter?

A device that is used to split a single-phase current into two (or) more currents changing within a phase is known as a phase splitter. Sometimes it is essential to supply two signals that are equivalent within amplitude although 180 degrees out of phase with each other. So, these two signals can be given from a single input signal with a phase splitter which is utilized to run a single-phase induction motor. The term “phase splitter” is most frequently used with amplifiers that generate two balanced equivalent amplitude of voltage outputs but reverse polarity but sometimes is used for generating quadrature signals.

How Does a Phase Splitter Work?

The phase inverter working is very simple in all the circuits of a tube amplifier. It takes a signal input & provides two outputs where one output is identical to the original or in-phase & other output is a mirror-image or phase-inverted/flipped phase. So throughout this operation, there is no signal amplification is required & the phase splitter normally has a unit gain to simply change the phase. Every signal feeds a power tube that is connected to every face of the primary winding of the output transformer within the push-pull configuration.

Phase Splitter Circuit

A phase splitter circuit is used to generate two output signals that are equivalent within amplitude however they are opposite from each other within phase from a single input signal. This is another kind of BJT configuration where a single input sinusoidal signal can be split into two different outputs that change within phase from each other at 180 degrees.

A phase splitter circuit using a single transistor circuit is shown below. This circuit simply combines the common emitter (CE) amplifier characteristics with a common collector (CC) amplifier. The circuit in the CC & CE amplifier circuit configuration is forward-biased for operating as a linear class-A amplifier to decrease output signal distortion.

If we combine both the common emitter & common collector amplifier configurations and take the outputs from both the emitter & collector terminals simultaneously, we can design a transistor circuit that generates two output signals that are equivalent within magnitude but reversed with each other.

Working

The Phase Splitter circuit is designed with a single transistor to generate inverting & non-inverting outputs which is shown below. In this circuit, the input signal is applied to the transistor’s base terminal and one output signal is taken from the transistor’s collector terminal & the second o/p signal is taken from the transistor’s emitter terminal. Therefore, the transistor phase splitter circuit is a dual output amplifier that generates complementary o/ps from both the emitter & collector terminals which are 180 degrees out-of-phase.

For the CE amplifier, the voltage gain is the ratio of RL to RE i.e., -RL/RE. Here, the minus sign specifies an inverting amplifier. If we want to make both the resistor’s values equivalent like; RL = RE, then the common emitter stage voltage gain would be equivalent to unity or -1.

For the common collector (CC) amplifier, the emitter follower amplifier circuit will have a non-inverting voltage gain near unity (+1) naturally. The two output signals from the emitter & collector terminals will be equivalent in amplitude although 180 degrees out-of-phase. So this makes the phase splitter circuit extremely helpful to give anti-phase or complementary inputs to another amplifier phase like; a class-B push-pull power amplifier.

Thus, for correct operation, the voltage divider network which is connected across the supply rail & ground should be selected to generate the proper stabilizing of the DC states for the o/p voltage swing from both the transistor terminals generating symmetrical outputs.

Types of Phase Splitter

There are different types of phase splitters which are discussed below.

Cathodyne Phase Splitter

The most commonly used phase splitter is a cathode phase splitter due to its simple design and also very effective. A cathodyne is a very simple method to split phases which needs one tube only & equivalent. In this phase splitter, the slightly below unity gain & quite limited headroom are the trade-offs for this simplicity. In this circuit, output signals cannot swing past the ground & the tube can also drop a part of the supply voltage with resistor loading, The cathode phase splitter is used in various popular guitar amplifiers like; the push-pull, most orange amps & various Ampegs.

Whenever the input signal of this splitter swings negative then the valve will decrease its conduction, thus the current throughout it drops. So the voltage drop across the two load resistors within the circuit also drops, which means the cathode voltage should drop whenever the anode voltage increases. Similarly, whenever the input signal swings positive the opposite occurs. The o/p from the anode is inverted whereas from the cathode terminal, it is not. When a similar current supplies throughout both loads, then signals generated across them will be the same but 180 degrees out of phase.

Paraphrase Phase Splitter

The paraphrase phase splitter is the simplest & oldest type. This splitter helps in tapping off the major signal lane & gives an additional gain stage thus it becomes inverted. The term ‘para’ means ‘side by side’ which describes the method the circuit makes a new lane in parallel with the original. However, the term ‘paraphrase’ is used mainly for other phase inverter circuits in the earlier.

The paraphrase phase splitter protects more headroom as compared to the cathode & it needs only an additional one (or) two resistors. But, the gain and output impedance of the two phases will be complex to match so this makes it unusual within hi-fi circuits, although an interesting alternative mainly for guitar amplification. This type of splitter configuration is very difficult to couple directly, so it limits negative feedback.

Long Tail Pair

The long tail pair phase splitter is very popular in push-pull hi-fi applications. This splitter preserves headroom and provides voltage gain. It has equivalent output impedance with the single caveat and the tail should be long for best performance.

In this circuit, the first triode can look like a grounded cathode amplifier. The second triode within this arrangement with grid grounded receives its signal from the cathode, which means it does not reverse the output at its anode. The cathode load shared is the ‘tail’ & is significant for good balance.
Usually, the tail impedance is higher, then better matches the output impedance & the gain of this splitter. The main drawback of this splitter is that it needs an additional triode, CCS, and negative rail to make it fairly more complicated as compared to other phase splitters.

Advantages & Disadvantages

The advantages of phase splitter include the following.

• Phase splitters are very simple to design.
• It can be connected directly to the before stage
• These are very linear.
• These are very simple to adjust & stable.
• They have less distortion.
• These have high gain.
• These have high amplitude output.
• They have less output impedance.

The disadvantages of phase splitter include the following.

• Phase splitters have less gain.
• These are very sensitive to the load
• These are not very linear due to the inside capacitances of the tube that are not the same between the grid & the plate (or) the grid & the cathode, although their values are generally low so that their effect is far away from the range of audio.
• The tubes of the splitter should be paired from a twin tube.
• The Quality depends extremely on the transformer.

Applications/Uses

The uses of phase splitter include the following.

• Phase splitter is significant within push-pull audio amplifiers.
• The DC-balanced phase splitter is used commonly in audio applications like pre-amplifiers & power amplifiers.
• A phase splitter circuit takes an input signal & splits it into two equivalent signals but a reverse phase.
• The practical uses of phase splitters are; these devices are used in the manufacturing industry for controlling the electrical motor speed in all kinds of industrial machines. These devices are used in the music instrument sector for amplifying power to sound equipment.
• By using phase splitters in the industrial sector, power conversion costs are significantly reduced.
• It is a significant component within audio & electrical engineering that separates a single signal into various phases by allowing balanced power distribution & improving the quality of sound within stereo systems.
• A phase splitter is an electronic circuit that is used within signal processing although they serve various functions.
• The phase splitter’s two output signals are used for driving a push-pull amplifier configuration to enhance the amplifier’s efficiency & decrease distortion.
• These are used within audio applications.
• A phase shifter circuit is used to shift an input signal’s phase by a certain amount.
• The phase shifter is used for adjusting the phase relationship between various signals (or) to make specific phase shifts mainly for signal processing applications.
• Phase shifters are used commonly in communication systems like; radio frequency applications.
• It is used to drive an amplifier within a balanced topology like; an H bridge or push-pull.
• These are used to drive balanced audio cables (or) balanced transmission lines.
• These are used to supply voltages within an oscilloscope to deflection plate pairs within the CRT.
• These are used to generate anti-phase signals utilized within some filter designs like; all-pass filters for approximate quadrature signals utilized within SSB signal generation (or) old quadraphonic decoders.

Thus, this is an overview of phase splitter, circuit, working, types, advantages, disadvantages, and applications. It is a type of device that divides a signal into various phases. It changes an AC signal’s phase; and generates an output of 90 degrees & 180 degrees phase shift from input. Here is a question for you, what is another name for a phase splitter?