WO2004034570A1

WO2004034570A1 - Envelope elimination and restoration amplifier and method thereof

Info

Publication number: WO2004034570A1
Application number: PCT/US2003/031938
Authority: WO
Inventors: Pierce Joseph Nagle; Andrei Grebennikov; Frank Sharpe; Gerard Quilligan
Original assignee: M/A-Com Eurotec Bv
Priority date: 2002-10-08
Filing date: 2003-10-08
Publication date: 2004-04-22
Also published as: KR20060034619A; AU2003282499A8; AU2003282499A1

Abstract

An RF amplifier is disclosed which comprises a plurality of power transistors whose output terminals are parallel connected to a load, while their respective input terminals are coupled through individual DC blocking capacitors to a common RF input terminal. Based on the envelope signal of the amplitude modulated FR signal to be amplified, digital control signals are generated which control in an ON/OFF manner the respective base bias currents applied to the respective base terminals of the power transistors. The ON/OFF control of an individual power transistor is done by a respective base biasing circuit which comprises a current mirror.

Description

ENVELOPE ELIMINATION AND RESTORATION AMPLIFIER AND METHOD THEREOF

FIELD OF THE INVENTION The invention relates generally to electromagnetic processing, and more particularly to the attenuation or amplification of electromagnetic waves.

BACKGROUND OF THE INVENTION

The controlled attenuation or amplification of electromagnetic waves has many uses. For example, intelligence may be conveyed along a wave by attenuating and/or amplifying

("modifying") electromagnetic wave characteristics, such as is seen when modulating amplitude, frequency or phase of an electrical current or radio frequency (RF) wave to transmit data. As another example, power may be conveyed along a wave in a controlled fashion by attenuating and/or amplifying electromagnetic wave characteristics, such as is seen when modulating voltage or current in a circuit. Moreover, the uses may be combined, such as when intelligence may be conveyed through a wave by modifying power characteristics.

Electromagnetic wave characteristic modification may be accomplished through digital or analog techniques. For instance, a wave may be switched off, and thus the wave attenuated completely; the voltage of a wave may be increased, such as by a factor of 1.5, and thus the wave regulated; etc. Digital and analog attenuation and/or amplification may also be combined, that is, the same wave may be subject to various types of digital and/or analog attenuation and/or amplification within a system in order to accomplish desired tasks.

Electromagnetic waves have, until fairly recently, been modified using analog techniques, and there had been no attempt to isolate discrete wave characteristics such as current, voltage and the like and modify those characteristics in order to modify the wave itself. Recently, however, wave modification techniques have become digitized, so that characteristics of the wave can be isolated and modified directly in order to achieve a desired result. Digitization has become desirable because it usually provides more speed and precision in wave modification while consuming less power than previous methods. Using digitization to process electromagnetic wave, such as in the amplification of a wave, has provided improved linearity of the processed wave, while at the same time also improving the efficiency of the process by reducing power consumption. Digitization also allows for the reduction of noise in the processed wave through the use of digital based techniques that are not available in analog processing systems.

Accordingly, it would be helpful to the art of electromagnetic wave modification if apparatus, methods, and articles of manufacture were provided that utilize digital techniques in the processing of electromagnetic waves.

SUMMARY OF THE INVENTION

Embodiments of the present invention include apparatus, methods and articles of manufacture for generating and/or modifying electromagnetic waves. In one embodiment, a method of processing an electromagnetic wave comprises regulating at least two independently controllable current sources with a signal determined from at least one characteristic of the electromagnetic wave to generate a processed electromagnetic wave from at least one of the independently controllable current sources. In another embodiment, an electromagnetic wave processor comprises a plurality of independently controllable current sources connected to use a signal determined from at least one characteristic of an electromagnetic wave. The signal is input to the plurality of independently controllable current sources to generate a processed electromagnetic wave from at least one of the independently controllable current sources.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a diagram illustrating an input wave.

Figure 2 is a diagram illustrating an embodiment of a wave processor.

Figures 3(a)-(c) are diagrams illustrating exemplary embodiments of a control circuit for a wave processor. Figure 4 is a chart illustrating states of a wave over time.

Figures 5(a)-(c) are diagrams illustrating the operation of embodiments of a segmented wave processor.

DETAILED DESCRIPTION Embodiments of the invention include apparatus, methods and articles of manufacture for wave or signal processing. The term "signal" as used herein should be broadly construed to include any manner of conveying data from one place to another, such as, for example, an electric current or electromagnetic field, including without limitation, a direct current that is switched on and off or an alternating-current or electromagnetic carrier that contains one or more data streams. Data, for example, may be superimposed on a carrier current or wave by means of modulation, which may be accomplished in analog or digital form. The term "data" as used herein should also be broadly construed to comprise any type of intelligence or other information, such as, for example and without limitation, audio, such as voice, text and/or video, etc. Figure 1 illustrates a schematic diagram of a wave that has been divided into two component characteristics. This wave may be an input wave, for example, to an electromagnetic signal transmitter, receiver, or transceiver. Input wave a has been divided into magnitude component a^m comprising magnitude characteristics of the input wave over period tj and phase component a^p, comprising phase characteristics of the input wave over the same period. The manner in which input wave a is divided is not particularly limited. One exemplary manner in which this may be accomplished is to provide input wave a to a digital signal processor, which digitizes the wave, such as by the use of rectangular coordinates or I,Q data. A rectangular to polar converter then receives the I,Q data and translates it into polar coordinates. It should be noted that, in other embodiments, a different digitized representation of a wave may be provided if desired. While the invention is described herein in connection with an embodiment using a digitized wave with polar data, those of ordinary skill in the art will appreciate that the invention is not limited thereto and may use any digital or analog waveform, or combination thereof.

Output wave b is shown after processing by a preferred embodiment. It should be noted that the time period in this and other embodiments is as desired. For example, embodiment may derive magnitude and phase characteristics of the wave over various time periods in order to maximize resolution of the wave, maximize speed of operation, etc. These time periods may be dynamically determined as well in various embodiments so that they change during operation. In the preferred embodiments, the division of the input wave is synchronized, in order to maximize accuracy of output and minimize any distortion.

Figure 2 shows an embodiment of a wave processor. The amplitude characteristics of the original input wave may be modulated along path a^m into digital pulses comprising a digital word quantized into bits Bl to Bn, with a Most Significant Bit ("MSB") to Least Significant Bit ("LSB"). It should be noted in Figure 2 that, for ease of viewing the figure, the control component lines are consolidated into a single path a^m leading into control components 22a-n. However, in the embodiment, and as further described below, the control component lines are not consolidated and instead feed into the control components individually. The digital word may be as of varying lengths in various embodiments. In general, the longer the word the greater the accuracy of reproduction ("resolution") of the input wave. The digital word provides instruction signals for processing of the wave, such as for attenuation and/or amplification, in manner to be described further below. Of course, as is described further below, in other embodiments, a differently composed digital word may be used, as well as other types of derivation of amplitude or other wave characteristics.

The phase characteristic component of input wave a travels along path a^p, where it is modulated onto a carrier wave, preferably an RF signal. This wave preferably has a constant envelope, i.e., it has no amplitude variations, yet it has phase characteristic information of the original input wave, and passes to wave processor 25. The wave, which has been split among individual driver lines, is then fed into current sources 21a-w, and will serve to potentially drive current sources 21 a-«, as is further described below. In other embodiments, as further described below, other sources of other wave characteristics may be used.

It should be noted that, in the present embodiment, transistors maybe used as current sources 21a- n. Additionally, in other embodiments, one or more transistors segmented appropriately may be used as current sources 21a-«. The current sources 21a-« in one preferred embodiment must not be configured to behave like voltage sources; for example, by saturating transistors, which will interfere with the desired current combining of the sources.

Path a^m (comprised of control component lines a 1 - a^m n as described above) terminates in control components 22a-n. In a preferred embodiment, these are switching transistors, and are preferably current sources, although, as further described below, in other embodiments, other sources of other wave characteristics may be used, as well as other regulation schemes. Control components 22a-g are switched by bits of the digital word output from the amplitude component and so regulated by the digital word output from the amplitude component. If the digital control word is a binary signal and an individual bit is "1" or "high," the corresponding control component may be switched "on", and so current flows from that control component to appropriate current source 2\a-n. As had been noted above, the length of the digital word may vary, and so the number of bits, control components, control component lines, driver lines, bias control lines, current sources, etc. may vary accordingly in various embodiments. Moreover, there does not have to be a one to one correspondence among digital word resolution, components, lines and current sources in various embodiments. Current sources 21a-« receive current from a control component if the control component is on, and thus each current source is regulated according to that component. In the especially preferred embodiments, an appropriate control component provides bias current to the current sources, as is described further below, and so the control component may be referred to as a bias control circuit, and a number of them as a bias network. In some embodiments, it may be desired to statically or dynamically allocate one or more bias control circuits to one or more current sources using a switching network if desired.. For example, the circuitry of control components 22a-« may be configured to control a particular one or more of transistors of segments 21a-«.

Examples of embodiments of control circuits are illustrated in Figures 3(a)-(c). It will be appreciated that while particular circuits and components are shown herein for purposes of explanation, the invention is not limited thereto. Different or additional components may be added and components may also be deleted.

Figure 3(a) illustrates a bias circuit that incorporates one reference transistor. In this example, output transistor Qo may represent one of transistor segments 22a-n, which, when switched on, contributes a predetermined amount of output current (RF_0L,_t) to the output of wave processor 25. A plurality of control circuits and output transistors may be provided to contribute the aforementioned current outputs. In this embodiment, a biasing voltage for transistor Q is varied in accordance with a respective control bit of the digital control word. As control voltage V_con is varied, varying current i flows through resistor Ri as determined by the gain G of transistor Qi. Current i thus controls the flow of current through transistor Q₂. The current from transistor Q₂is used to control the predetermined current to be outputted from transistor Qo- The phase portion of the input wave a^p is inputted at RF_m, where it may pass components such as capacitor C_, which acts to block DC components from the signal. When the control bit is "on", current flows though the circuit and output transistor Qo contributes its output current to the output of wave processor 25. In this example, output transistor Q₀ has a gain that is ten times that of transistor Qι,however, as should be understood, other values may be used as well. Output transistor Qo is biased by voltage V_cc. The current outputted from the collector of output transistor Q₀ is filtered by inductor L_ and capacitor C₂, which act to provide filtering of the output signal RF_0Ut-

Each of the outputs from each of the output transistor segments that are switched "on" in this manner contribute their respective currents to the output of wave processor 25, (while the transistors that are switched "off do not), thus processing input wave a to form output wave b.

Figure 3(b) illustrates another embodiment of a control circuit. This circuit incorporates a feedback loop in the form of a differential amplifier. Control voltage V_con is controlled to vary in accordance with a bit from the digital control word, as described above. When the received control bit of the digital word is "on", control voltage N_con increases, which correspondingly increases the difference in base-emitter voltages of the differential pair transistors, Qi and Q₂. The difference in current created by changes in V_con is thus amplified by transistors Qi and Q , which are connected at their emitters, as shown. Components, such as Rι-R₇ are included for biasing. Feedback elements R_f and C_f act as a low-pass filter to feedback transistor Q . Transistor Q₄ (and biasing components, such as R₈-Rι₀) act on the current output as well to provide a source of control current to output transistor Q₀.

Figure 3(c) illustrates a third embodiment of a control circuit. In this exemplary embodiment, a differential amplifier stage 301 is located between a diode circuit 302 and control current supplying circuit 303. Differential amplifier stage 301 preferably includes two transistors, Q₃ and Q₄, which are connected to each other at their emitters, as shown. Differential amplifier stage 301 also includes biasing components, such as R -R₇.

When the received control bit of the digital word is "on", control voltage V_con increases, which correspondingly increases of the base-emitter voltage of the transistor Q . The base potential of the transistor Q₄ is fixed by diode-connected transistor Qi. Therefore, the difference in base-emitter voltages of the differential pair transistors, Q and Q₄, causes an increase in the collector current of the transistor Q₃ and an increase in the voltage drop through the resistor R₃. Consequently, the value of the reference voltage applied to the base terminal of the transistor Q₂ is reduced. And, the output current from current supplying circuit 303 is used to control the output of current source 304 in the manner previously described. Each of the outputs from each of the selected segments combine to form the output of wave processor 25. The digital control word of amplitude component a^m may be configured or coded in any desired manner for operating the above-described segments in any desired manner. By way of illustration, in one preferred embodiment the digital control word contains seven bits to represent a wave characteristic of the input wave a, such as amplitude. Each configuration of these seven bits represents a different input state to wave processor 25, where each input state may correspond to a digital representation of the wave characteristic. This is further illustrated in Figure 4 for this example. If the control bits are configured in a binary system, then seven control bits may be configured in 2⁷ or 128 different ways, allowing for 128 different input states to wave processor 25. Each of these 128 states may represent, for example, a discrete amplitude level or range of input wave a. As can be seen from Figure 4, the greater the number of control bits, the greater the number of input states, and hence the greater the resolution of the wave processor.

The coding system that may be employed in accordance with the embodiments disclosed herein is not limited and may include any digital representation of a characteristic of an input wave a that may be used to control wave processor 25 in any manner. In an especially preferred embodiment, the digital representation is of the amplitude of the input wave and comprises a binary digital word having seven bits, where each bit, from the most significant bit ("MSB") to the least significant bit ("LSB") is used to control a designated segment or segments of wave processor 25 to generate an output current.

In this preferred embodiment, each bit represents the number 2 raised to a power (1 , 2, 4, 8, 16, 32, and 64) and one or more of these bits are combined to designate a number corresponding to the wave characteristic of input wave a, such as amplitude. If a bit is switched high or "on" ("1"), it is counted; if it is switched low or "off ("0"), it is not counted. Thus, for example, if the digital word represents the number "63", then the bit representing the number 64 would be off (or "0") and the bits for 32, 16, 8, 4, 2, and 1 would be on ("0111111"). Adding the designated bits together equals 63 (32 + 16 + 8 + 4 + 2 + 1 = 63). If the digital word represents the number "64", then only the bit representing the number 64 would be on, and the others would be off ("1000000").

Each segment of wave processor 25 receives current from one or more of the control components based upon these control bits and may be biased to serve as a potential current source. The segment may or may not act as a current source, because it is regulated via the appropriate digital word value regulating the control component, and activation of a segment is dependant upon the value of the appropriate bit from the digital representation of the amplitude component, and concomitant regulation of the appropriate control component.

In one embodiment, the segments are varied in size such that the first segment a is twice the size of the next segment b, which in turn is twice the size of the next segment c, and so on until reaching the final segment n. The largest segment a is controlled by the MSB of the amplitude word, the next bit of the word to the next largest segment, etc., until the LSB, which is sent to the smallest segment. Alternatively, the segments may be sized and grouped so that a particular group of segments may represent a particular bit of the control word. Of course, as noted above, other embodiments may have a different pattern of matching bit to segment. In other embodiments, other wave characteristics may be fed to another source of wave characteristics and so regulate that source.

As the digital control word changes over time, one or more of segments may become a current source, contributing a corresponding amount of current to the output of wave processor 25. The current output from each segment is thus combined at the output of wave processor 25 to drive load R_L. The current is outputted from wave processor 25 in relation to the input state of the wave processor as designated by the digital control. The input state changes as the digital control word changes, which, in turn, changes the segments that contribute current to the output, thus processing the input wave in the determined manner, e.g., amplification.

The foregoing is further illustrated by Figures 5(a)-(b). In this example, each segment, or group of segments, may represent a number corresponding to an input state. For example, as shown in Figure 5(a), seven segments may be used to each represent a number corresponding to the significance of one of the seven bits of the digital control word, i.e., 64, 32, 16, 8, 4, 2, and 1. Each segment may be sized or weighted in this example to contribute a proportionate amount of current to the output when acting as a current source. For example, a segment representing the number "64" may contribute twice as much current as a segment representing the number "32". When the digital word inputted to the wave processor designates a particular input state, the control components switch on segments that combine to designate that state. For the example shown in Figure 5(a), if the input state is "63", then segments 1, 2, 4, 8, 16, and 32 are turned on to contribute current and the segment representing 64 is turned off. When the digital word, and thus the input state, changes (for example, to "64"), then the control components switch off segments 1, 2, 4, 8, 16, and 32, and switch on the segment representing 64. Alternatively, as shown in Figure 5(b), some of the segments may be evenly weighted, but more than one segment may be grouped to designate a number for the input state. In this example, eleven segments may be used to represent the seven bits of the digital control word. Seven of the segments each represent the number 16, while the remaining segments represent the numbers 8, 4, 2, and 1. Four of these segments may thus be combined to represent the number 64, two may be combined to represent the number 32, etc.

Weighting the segments in this manner allows for the segments to be combined in a variety of ways to achieve the desired state. Thus, as shown in Figure 5(c), in switching from state "63" to state "64", the four smaller segments (8, 4, 2, 1) may be switched off and only one 16 segment need be switched on to achieve the desired change in state. The use of smaller segments is advantageous, for example, when switching transistors, because it may reduce noise that may occur in the processed signal due to inherently larger capacitance noise in the switching of larger transistors.

Returning now to the embodiment of Figure 2, each current source serves as a potential current source, and is capable of generating a current, which is output to current source lines 21a- n respectively. It should be noted that the current sources are not an amplifier or amplifiers, in the preferred embodiments, rather the plurality of current sources function as an amplifier, as is described herein. Indeed, amplification and/or attenuation may be considered in the preferred embodiments as functions of those embodiments, and so may an amplifier and/or attenuator be considered to be an electrical component or system that amplifies and/or attenuates.

The combined current, i.e. the sum of any current output from current sources 21a-n, is the current sources output. Thus, an embodiment may act as an attenuator and/or amplifier. In preferred embodiments, no further circuitry or components are necessary between current sources to combine current from each current source and so provide a useful output current. Therefore, the combined current, which is output on line 26, and shown as b, may be used as desired, e.g., as an amplifier, as an attentuator, to drive a load, etc.

It should be noted that, in the invention, the current sources are biased non-linearly. Thus, any current source operates efficiently. In the preferred embodiments, therefore, power consumption is reduced. Additionally, as a result of current source regulation according to signal characteristics, as had been described above, the resultant output signal has a relatively accurate linearity and proportionality with the input signal. Thus, an amplifier may be provided in the preferred embodiments with the relative precision of linear operation combined with the relative efficiency and power consumption of non-linear operation.

For example, returning to the embodiment of Figure 2, if one of current sources 21a-« is switched on, it will act as a non-linear current source with attendant relative efficiency. If the current source is off, the source consumes little or no power. Linear characteristics are seen as well because each current source that is on provides current contribution in similar proportions to the amplitude characteristic of the input signal, and so a relatively precise reproduction of the input signal is provided.

The current sources 21a-n may comprise, in the preferred embodiment of Figure 2, one or more HBT transistors. Other transistors may be used as well, such as FETs, etc., as well as other current sources. Other components may be interposed as well, e.g., a variable gain amplifier or attenuator to reduce the drive current to the transistor segments, non-linear components along the amplitude path, etc.

The use of the preferred embodiments may provide a capability for wide band amplitude modification in an associated transmitter because it makes possible linear amplification and/or attenuation across a relatively large frequency spectrum, due to the relatively low input capacitance. Thus, embodiments may be used for cellular and other transmitters, as is described further herein.

Advantageously, embodiments of the present invention may improve efficiency over conventional power amplification, because linearity of the transmission is not dependent on the linearity of the amplifier, but instead depends only on how linearly the currents add to the load. Accordingly, each current source can be biased as a non-linear current source, such as Class B or C, to maximize the efficiency. Efficiency may further be improved because there is little or no quiescent current draw for disabled current sources. In the illustrated embodiments, power control may readily be achieved because the output current is dependent primarily on the signal drive level. Increasing or decreasing the signal drive level, for example, with a variable gain amplifier or attenuator, causes a corresponding increase or decrease in the output current. In addition, an increase or decrease of the bias to the drive controller, also causes a respective increase or decrease in the output current. As should be understood, any suitable types of current sources, for example, other transistor segments and/or formats, as well as other devices or methods, may be used with any of the embodiments of the present invention where desired.

In embodiments fabricated as a single integrated circuit, weighting may be achieved by providing segments having different semiconductor areas. For example, when the area of a segment is reduced in size by half, the current supplied by the segment to the load is also reduced in half. This is because the smaller segment has half the current density of the larger segment.

Amplifiers according to embodiments of the invention can provide a direct digital interface for baseband DSP functions. The amplifiers also may be dynamically programmed to accommodate multiple modulation formats and wireless network standards. An advantage is that cost and size of devices using an amplifier based on this aspect of the invention can be reduced. Furthermore, the output current combines into the load to develop a voltage that can be an analog representation of the amplitude characteristic, so that the amplifier also performs a digital-to- analog conversion. Various types of system architectures may be utilized for constructing the embodiments of the present invention. One of ordinary skill in the art will accordingly appreciate that embodiments of the invention or various components and/or features thereof may be entirely comprised of hardware, software or may be a combination of software and hardware. The embodiments or various components may also be provided on a semiconductor device where desired, such as an integrated circuit or an application-specific integrated circuit composition; some examples include silicon (Si), silicon germanium (SiGe) or gallium arsenide (GaAs) substrates.

Various embodiments may modify various parameters without departing from the spirit and scope of the present invention. For example, the length of the digital word may be longer or shorter in various embodiments, which may provide a more or less precise digitization of the wave. As other examples, as was described further above, the number of bits, control components, control component lines, driver lines, bias control lines, current sources, etc., may all be varied as desired.

While the invention has been described by illustrative embodiments, additional advantages and modifications will occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to specific details shown and described herein. Modifications, for example, may be made without departing from the spirit and scope of the invention. In addition, preferred embodiments may include amplifiers that are specialized for particular input signals, carrier waves and output signals e.g. embodiments may be used in various RF, microprocessor, microcontroller and/or computer devices, e.g. cell phones, such as CDMA, CDMA2000, W- CDMA, GSM, TDMA, as well as other wired and wireless devices, e.g. Bluetooth, 802.1 la, -b, - g, , radar, lxRTT, two-way radios, GPRS, computers and computer communication devices, PDA's and other handheld devices, etc. Accordingly, it is intended that the invention not be limited to the specific illustrative embodiments, but be interpreted within the full spirit and scope of the appended claims and their equivalents.

Claims

CLAIMSWhat is claimed is:

1. A method of processing an electromagnetic wave comprising: regulating at least two independently controllable current sources with a signal determined from at least one characteristic of said electromagnetic wave to generate a processed electromagnetic wave from at least one of said independently controllable current sources.

2. The method of Claim 1, wherein said signal has a plurality of signal components and wherein one or more of said independent current sources is associated with a component in said signal.

3. The method of Claim 1, wherein said signal has a plurality of signal components and wherein each of said independently controllable current sources represents a component of said signal and provides an output current corresponding to said component.

4. The method of Claim 1, wherein said signal has a plurality of signal components and wherein a plurality of said independently controllable current sources together represents a component of said signal and provides an output current corresponding to said component.

5. The method of Claim 1, wherein said independently controllable current sources are configured so that the fewest number of said independently controllable current sources will change when said signal changes.

6. The method of Claim 1, wherein said signal is a digital signal.

7. The method of Claim 1, wherein said signal is a binary number.

8. The method of Claim 1, wherein said signal is a seven bit binary number.

9. The method of Claim 1, wherein said independently controllable current sources are regulated by a control component configured to control the one or more of of said independently controllable current sources based upon said signal.

10. The method of Claim 9, wherein said control component controls current to said one or more independently controllable current sources.

11. The method of Claim 9, wherein a plurality of control components comprise a bias control network configured to control biasing said independently controllable current sources.

12. The method of Claim 1, wherein said independently controllable current sources comprise one or more transistors.

13. An electromagnetic wave processor comprising: a plurality of independently controllable current sources connected to use a signal determined from at least one characteristic of an electromagnetic wave that is input to said plurality of independently controllable current sources to generate a processed electromagnetic wave from at least one of said independently controllable current sources.

14. The electromagnetic processor of Claim 13, wherein said signal has aplurality of signal components and wherein one or more of said independent current sources is associated with a component in said signal.

15. The electromagnetic processor of Claim 13, wherein said signal has a plurality of signal components and wherein each of said independently controllable current sources represents a component of said signal and provides an output current corresponding to said component.

16. The electromagnetic processor of Claim 13, wherein said signal has a plurality of signal components and wherein a plurality of said independently controllable current sources together represents a component of said signal and provides an output current corresponding to said component.

17. The electromagnetic processor of Claim 13, wherein said independently controllable current sources are configured so that the fewest number of said independently controllable current sources will change when said signal changes.

18. The electromagnetic processor of Claim 13, wherein said signal is a digital signal.

19. The electromagnetic processor of Claim 13, wherein said signal is a binary number.

20. The electromagnetic processor of Claim 13, wherein said signal is a seven bit binary number.

21. The electromagnetic processor of Claim 13, wherein said independently controllable current sources are regulated by a control component configured to control the one or more of of said independently controllable current sources based upon said signal.

22. The electromagnetic processor of Claim 21, wherein said control component controls current to said one or more independently controllable current sources.

23. The electromagnetic processor of Claim 21 , wherein a plurality of control components comprise a bias control network configured to control biasing said independently controllable current sources.

24. The electromagnetic processor of Claim 13, wherein said independently controllable current sources comprise one or more transistors.