Emitter-coupled Pair Research Articles

Emitter-coupled pair chaotic generator circuit

An emitter-coupled pair chaotic generator is proposed with a control parameter that can be tuned for distinct chaotic behaviors. The proposed circuit is a compact, high-speed implementation of the chaotic map based on the hyperbolic tangent function. It is demonstrated that the circuit and map parameters are analytically related. As an application, we design a random number generator that passes all NIST statistical tests by applying a post-processing to the balanced bit sequence generated by a quantization of the circuit output.

A 3.3/2.5 V-Supply 2400 mV-Swing Single-Ended SiGe BiCMOS Driver With Programmable Preemphasis for 3 Gb/s Data Transmission Over 75 <formula formulatype="inline"><tex Notation="TeX">$\Omega$</tex></formula> Coaxial Cable

This paper presents a quad single-ended cable driver delivering 2400 mV swing on each channel when double-terminated with 75 Ω loads from a 3.3 V termination supply. Fabricated in 0.18 μm SiGe BiCMOS it implements a switched current source to replace the conventional current steering emitter-coupled pair, with output swing controlled via replica biasing in place of a current mirror. All outputs meet industry-standard specifications for SD (270 Mb/s), HD (1.485 Gb/s), and 3G (2.97 Gb/s) data rates across the industrial temperature range, and the device is rated to withstand 4 kV human body model electrostatic discharge. The high swing can be applied directly to compensate for broadband implementation losses or configured to provide up to 9 dB of programmable preemphasis, extending the specified compliance point to the far end of 2 5 m (3G rate) or 40 m (HD rate) of Belden 1694A coaxial cable.

Differential Amplifier With Current-Mirror Load: Influence of Current Gain, Early Voltage, and Supply Voltage on the DC Output Voltage

A differential amplifier composed of an emitter-coupled pair is useful as an example in lecture presentations and laboratory experiments in electronic circuit analysis courses. However, in an active circuit with zero input load <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">id</sub> , both laboratory measurements and PSPICE and LTspice simulation results for the output voltage <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> are considerably lower than one base emitter unit <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BE(on)</sub> below the supply voltage <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</sub> , as predicted by a textbook derivation. Modification of the derivation to include the p-n-p transistor base currents and the current gain β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> and the supply voltage and specifications for the four transistors provide equations that predict results for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> that are consistent with laboratory experience and computer simulations. The output voltage is in excess of three <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BE(on)</sub> units below <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</sub> when β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> is 50. At larger values for β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> , <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> is increased by a factor proportional to 1/β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> , reaching one <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">BE(on)</sub> unit below <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</sub> as β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> approaches infinity. Larger values for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</sub> cause an additional modest difference between <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</sub> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> at low values for β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> . The derived equations and LTspice values are used to develop an empirical equation that predicts output voltages for the given Early voltages. The technique is adaptable to student data evaluation assignments. The computer simulations also showed that increased supply voltage results in increased gain for a given input value for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">id</sub> , while larger values for β <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">P</sub> result in a modest increase in gain at all values of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CC</sub> .

Stability analysis of circuits including BJT differential pairs

In this paper, a necessary and sufficient condition for robust stability of electronic circuits at high frequency, which contain differential pair (emitter–coupled pair), is proposed. In fact, when emitter–coupled pairs are used as one input signal–one output signal, they have uncertainty in their transfer functions at high frequency. Even it is shown that this uncertainty can cause instability in closed loop electronic circuits at high frequency.The uncertainty is modeled as multiplicative perturbation in the transfer function of the differential pair at high frequency. Based on this uncertainty model, a necessary and sufficient condition for robust stability of above electronic circuits at high frequency is presented. This condition guarantees internal stability of the circuit at high frequency with respect to the uncertainty.

A 20-GHz low-noise amplifier with active balun in a 0.25-/spl mu/m SiGe BICMOS technology

A 20-GHz low-noise amplifier (LNA) with an active balun fabricated in a 0.25-/spl mu/m SiGe BICMOS (f/sub t/=47 GHz) technology was presented by the authors in 2004. The LNA achieves close to 7 dB of gain and a noise figure of 4.9 dB with all ports simultaneously matched to 50 /spl Omega/ with better than -16 dB of return loss. The amplifier is highly linear with an IP/sub 1dB/ of 0 dBm and IIP/sub 3/ of 9 dBm, while consuming 14 mA of quiescent current from a 3.3-V rail, with temperature-compensated biasing. To the authors' knowledge, the LNA delivers the lowest reported noise figure and highest linearity for a silicon implementation of a combined active balun and LNA at 20 GHz, and is the first implementation of an active balun with an LC degenerated emitter-coupled pair. Here we expand on that work, with an analysis of the balun operation and noise optimization of the design.

Technique for improving high-frequency CMRR of emitter-coupled differential pairs

A technique for improving the high-frequency common-mode rejection ratio (CMRR) of emitter-coupled differential pairs by means of tail bootstrapping is presented. Analytical and measured results are presented to validate the concept.

Realization of a linearized transconductor based on the multitail technique

A new linearization technique of the multitail trans-conductor is presented. In this technique, the parameter conditions for the maximally flat transconductance are easily obtained by comparing the coefficients of denominator and numerator of an output current expanded into a polynomial function using a Taylor expansion. In this paper, linearized transconductors with two, three, and four emitter-coupled pairs are described and discussed. SPICE simulation results show that the total harmonic distortion is less than, 1% for an input signal of 1 Vp–p at 100 kHz. © 2000 Scripta Technica, Electron Comm Jpn Pt 2, 83(12): 42–51, 2000

Realization of a triple-tail cell with high input resistance for low-voltage application

An operational transconductance amplifier (OTA) is a useful function block for analogue signal processing. A triple-tail cell possesses a wider linear input voltage range than an emitter-coupled pair, in spite of its simple configuration. In practical implementation of the triple-tail cell, the maintenance of the intrinsic linearity necessitates a voltage divider which has low resistance. This lowers the input resistance of the triple-tail cell. This paper describes a method of realizing high input resistance of the triple-tail cell. An active voltage divider composed of two OTAs is connected to the triple-tail cell. The linearity of the triple-tail cell with the divider deteriorates little. The whole circuit can operate at a low supply voltage. Although an emitter-coupled pair is employed as the OTA in the active divider, the linearity of the divider is good. Simulation results of an OTA-C filter that consists of the triple-tail cell and capacitors show that satisfactory characteristics are obtained.

Large Signal Analysis of Low-Voltage Bipolar Analog Functional Elements using Fourier-Series Approximations

This paper discusses the large signal performance of low-voltage analog functional elements built around bipolar-junction transistors. Fourier-series approximations are obtained for the transfer characteristics of the basic building blocks; such as the balanced emitter-coupled pair, the unbalanced emitter-coupled pair with different transistor sizes, the emitter-coupled pair with bias offset and the triple-tail cell. Using the Fourier-series approximations of these basic building blocks, closed form expressions are obtained for the amplitudes of the harmonics and intermodulation products at the output of analog functional elements; such as the basic differential pairs, squaring circuits, operational transconductance amplifiers, multipliers, mixers and triplers, excited by a multisinusoidal input signal. Using these expressions comparison between the large signal performance of analog functional elements can be performed and the parameters required for a predetermined performance can be determined.

A 2-V 1.9-GHz Si down-conversion mixer with an LC phase shifter

This paper describes a 2.0-V 1.9-GHz silicon down-conversion mixer with an LC phase shifter in a 20-GHz bipolar process. In this circuit, the lower emitter-coupled pair in a Gilbert cell mixer is removed to enable low voltage operation, and instead an LC phase shifter is inserted between two current sources. The time constant of the LC phase shifter has to be optimized, because the phase shifter acts as a low-pass filter and the lower cutoff frequency results in the loss of signal power. By this optimization, it can keep both high conversion gain and low distortion. The experimental results show conversion gain of 7.0 dB and the input third-order intercept point of -1.0 dBm are realized at 2.0 V.

The ultra-multi-tanh technique for bipolar linear transconductance amplifiers

A novel circuit design technique for bipolar linear transconductance amplifiers is presented. A triple-tail cell, which consists of three emitter-common transistors biased only by a current source, is exchangeable with symmetrical cross-coupled, emitter-coupled pairs in a multi-tanh cell, such as a multi-tanh doublet, or a multi-tanh quad. Therefore, the multi-tanh technique is further theoretically expanded to the ultra-multi-tanh technique. In this paper, the ultra-multi-tanh technique is proposed and discussed, and furthermore, an ultra-multi-tanh doublet is verified with bipolar transistor-arrays and discrete resistors on a breadboard.

A bipolar low-voltage quarter-square multiplier with a resistive-input based on the bias offset technique

A bipolar low-voltage quarter-square multiplier is presented. The proposed multiplier is very simple because the multiplier cell is built from four identical emitter-coupled pairs connected in parallel and its input system is realized using resistive dividers. Therefore, it is also very practical because it is easy to implement the circuit on a large scale integration (LSI). The fundamental characteristics at a 1 V supply voltage were verified on a breadboard using transistor-arrays and discrete components, it is, furthermore, very suitable for low-power operation.

The super-multi-tanh technique for bipolar linear transconductance amplifiers

A novel circuit design technique for bipolar linear transconductance amplifiers is presented. A triple-tail cell, which consists of three emitter-common transistors biased by a single tail current, is exchangeable with an emitter-coupled pair in the multi-tanh cell, such as a multi-tanh doublet, a multi-tanh triplet or a multi-tanh quad. Therefore, the multi-tanh technique is further theoretically expanded to the super-multi-tanh technique. In this paper, the super-multi-tanh technique is proposed and discussed, and furthermore, a super-multi-tanh doublet is verified with bipolar transistor-arrays and discrete resistors on a breadboard.

Linearization techniques for bipolar emitter-coupled pairs: a comparative study

Bipolar emitter-coupled pairs are basic building blocks in many analogue integrated circuits. Because of the high intermodulation and adjacent channel radiation performance requirements, state of the art communication electronic circuits require extremely linear transfer functions of the emitter-coupled pairs and several techniques have been proposed for their linearization. In this paper, a comparative study of these linearization techniques is presented. A simple procedure for approximating the transfer characteristics of an emitter-coupled pair is proposed and closed-form expressions are obtained for the amplitudes of the intermodulation products at the output of an emitter-coupled pair excited by a multisinusoidal input signal. Using these expressions comparison between the different linearization techniques can be performed and the optimum linearization technique required to meet a predetermined intermodulation performance can be decided.

Some circuit design techniques using two cross-coupled, emitter-coupled pairs

A circuit structure having two cross-coupled, emitter-coupled pairs is proposed as a fundamental analog function element for multiplying two electrical input quantities; the input voltage difference and the tail current difference. The simplest form is well-known as "the Gilbert multiplier cell." In this circuit, the tail current difference is the differential output current of an emitter-coupled pair, nearly proportional to the differential input voltage. Therefore, if the tail current difference is the differential output current of a squaring circuit, nearly proportional to the square of the differential input voltage, a squaring multiplier is obtained and ran be used for radio communication applications as a frequency mixer with a local oscillator frequency doubler. If the tail current difference is the differential output current of a multiplier then a tripler, capable of multiplying three electrical input quantities, is obtained. The folded technique, for low voltage operation, and the multi-tanh technique, for input voltage range expansion, are employed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A bipolar four-quadrant analog quarter-square multiplier consisting of unbalanced emitter-coupled pairs and expansions of its input ranges

A bipolar four-quadrant analog multiplier based on the quarter-square technique, which is constituted from unbalanced emitter-coupled pairs, and some methods for extending the input voltage range, are described. The building blocks for the circuit consist of an unbalanced emitter-coupled pair with different emitter areas, an emitter-coupled pair with an input bias offset, and an unbalanced emitter-coupled pair with unbalanced emitter degeneration. A basic squaring circuit is realized from two identical unbalanced emitter-coupled pairs with emitter area ratio K and cross-coupled inputs and parallel-connected outputs. The quarter-square multipliers proposed in this paper can operate under low supply voltage (typically >

Schaltverhalten des Differenzverstärkers

The emitter-coupled pair still is the core of the fastest circuit-families, the ECL- or CML-schemes. We shortly revisit the static behaviour of the circuit and investigate then its dynamic behaviour when used as a digital shifter. Taking into account the nonlinear and the dynamic effects of the bipolar transistor we will develop an analytical expression for the delay time that describes the functional dependency upon the circuit- and device parameters.

Frequency mixer with a frequency doubler for integrated circuits

We have developed a bipolar LSI, including a frequency mixer and a local oscillator frequency doubler. The local oscillator frequency doubler consists of two identical unbalanced emitter-coupled pairs with a different emitter area ratio, whose input terminals are connected cross-coupled and whose output terminals are connected in parallel, and is coupled with the frequency mixer directly in the LSI. The fabricated LSI operates on supply voltage as low as 2.7, and has been put into practical use for a cordless telephone system.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Bipolar differential pair DC transfer characteristics

Starting from the partition function the energy of a system which leads to the derivation of collector currents in the circuit is determined. From the currents the large-signal transfer characteristics of the emitter-coupled pair are obtained. This new technique provides an insight into the statistical nature of charge carriers in a system.

Realization of a 1-V active filter using a linearization technique employing plurality of emitter-coupled pairs

A low voltage (1 V), low-power (100 mu W), and low-frequency (9 kHz) fifth-order fully integrated active low-pass filter (LPF) using a bipolar technology is described. Novel highly linear transconductors consisting of N emitter-coupled pairs were designed for low-voltage operation. The linear input range is expanded to about 100 mV/sub p-p/ at 1% error with N=4, which is about twice that of the conventional linearization technique. The filter is basically a gyrator-capacitor type, in which gyrators are implemented by using the linearized transconductors. Large time constants were realized with very low current (540 nA/transconductor) owing to the high transconductance-to-operating-current ratio of the linearized transconductors. Measured results show a passband ripple of 1.5 dB, a minimum stopband rejection of 70 dB, and a dynamic range of 56 dB, despite a very high nominal impedance (400 k Omega ). Practical limitations of this approach are also discussed, such as the sensitivity of the linearized transconductors against process variations, noise, and frequency limitations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>