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| Telephone ringing extender |
| In the drawing, a subscriber telephone loop shown as ring conductor 10 and tip conductor 11 is ... |
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| Speakerphone test set |
| This and other needs are met by the present invention which provides a telephone test set having ... |
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| Laser diode system |
| OF AN ILLUSTRATIVE EMBODIMENT OF THIS INVENTION FIG. 1 shows a laser bar 10 with, illustratively, ... |
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| Digital time division multiplex telecommunication network |
| In accordance with the invention, the foregoing and other objects are achieved in that the TDM ... |
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| Roulette-type game apparatus |
| What is claimed is: 1. A roulette-type game apparatus comprising: a base (11); a signaling plate (30... |
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| Wood type golf club |
| I claim: 1. A distance wood type golf club having a head, a relatively large flat top surface, a ... |
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Amplifier circuit having high linearity for cancelling third order harmonic distortion
| Details |
Inventors: Main, W. Eric; Durec, Jeffrey C.;
Assignee: Motorola, Inc. (Schaumburg, IL)
Primary Examiner: Mullins; James B.
Assistant Examiner:
Attorney, Agent or Firm: Hoshizaki; Gary W.
A amplifier (21) having increased linearity, low input impedance, and low noise is provided. The amplifier (21) has an input (22), a bias input, a first output (23), and a second output (33). A first transistor (26) has a collector coupled to the first output (23), a base coupled to the bias input, and an emitter. A first resistor (27) is coupled between the emitter of the first transistor (26) and the input (22). A second transistor (29) has a collector and base coupled in common, and an emitter coupled for receiving a power supply voltage. A second resistor (28) couples between the input (22) and the common base and collector of the second transistor (29). A third transistor (32) has a collector coupled to the second output (33), a base coupled to the common base and collector of the second transistor (29), and an emitter coupled for receiving the power supply voltage. An input signal applied to the input (22) generates a differential current at the first and second outputs (23, 33). The input signal and the differential current have a linear relationship. |
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DETAILED DESCRIPTION An amplifier is an element common to many analog circuits.
For example, amplifiers are used in analog mixers, filters, multipliers, and oscillators.
An input signal is applied to an amplifier and amplified by the amplifier.
The relationship between an input signal applied to an amplifier and an output signal provided by the amplifier is known as a transfer function.
In general, an amplifier having a transfer function that is linear or has a linear relationship between the input and output signals is useful for many different circuit applications.
The transfer function is not the only parameter of importance in the design of an amplifier, other parameters that affect the performance of an amplifier are transconductance, dynamic range, frequency range, noise, and power dissipation.
FIG.
1 is a prior art schematic diagram of an amplifier 11.
Amplifier 11 is a transconductance amplifier and is widely used in circuits requiring a wide input voltage range and high linearity.
Furthermore, amplifier 11 is commonly used in mixer circuits operating at high frequencies.
Amplifier 11 comprises a differential input stage 12 and a differential input stage 13.
Current sources 14 and 15 respectively bias differential input stages 12 and 13.
Amplifier 11 utilizes two offset transfer functions that, when summed, increase the dynamic range.
The offset transfer functions are created by differential input stages 12 and 13 being unbalanced.
An unbalanced differential input stage comprises transistors having different emitter areas.
In FIG.
1, the transistors which comprise either differential input stage 12 or 13 differ in size by an emitter area ratio of M.
The linear range of amplifier 11 is determined by the emitter area ratio of the transistors which comprise differential input stages 12 and 13 and the current magnitude of current sources 14 and 15.
The response of amplifier 11 becomes non-linear as the current provided by current sources 14 or 15 predominantly goes through one of the transistors which comprise either differential input stage 12 or 13
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