Common-collector Amplifier Research Articles

Novel complementary Sziklai pair based high gain low noise small-signal amplifiers

<span lang="EN-US">A new paired configuration of opposite polarity BJTs, the “complementary Sziklai pair” is introduced in the series of multi-BJT-based devices like Darlington and Sziklai pair, and its viability is tested in small-signal common emitter (CE) and common collector (CC) amplifier configurations. The Darlington and Sziklai both face the problem of poor frequency response at a higher frequency which is addressed by the proposed configuration. The proposed pair with CE amplifier holds class-A amplification property with a high voltage gain of 200.05, a high current gain of 11.62, wider bandwidth of 1.64 MHz, and a low THD of 1.29E-6%, hence supports the potential of wide applicability in analog communication. Similarly, the proposed pair with CC configuration produces approximately a unit current gain of 0.99 with wider bandwidth of 1.90 MHz and low THD of 1.76E-6%, therefore it can be used as a current buffer in a generalized current follower circuit. Conclusively, the device structure of this new BJT pair may be considered the third consecutive member of the series of Darlington pair and Sziklai pair. The layout of the proposed CE and CC amplifier occupy small areas of 158.30 μm<sup>2</sup> (10.23×15.47 μm) and 141.16 μm<sup>2</sup> (10.20×13.84 μm) respectively in 180 nm process technology.</span>

Design and Analysis of Wideband PNP Sziklai Common Collector Amplifier with High Current Gain

Design and Analysis of Wideband PNP Sziklai Common Collector Amplifier with High Current Gain

Design and Simulation of a Multistages Common-Emitter, Common-Collector, AC Voltage Amplifier

The main function of the ampifier is to increase the signal strength, in terms of its voltage or current. In this research, a multistages ac voltage common-emitter amplifer and common-collector amplifier with a single supply of +15 V was designed. The objective is to design an amplifier for amplifying a small ac signal from a transducer. The transducer has an output impedance of 10 k. The amplifier will have a small-signal gain in order of about 1500 and a small-signal bandwith ranging from 100 Hz to 20 kHz. It will drive a load of 300 Ω. The entire circuit consists of a first stage common-emitter configuration gain amplifier, another second stage common-emitter configuration gain amplifier, and a third stage buffer unity gain common collector amplifier. The three-stages was capacitor coupled. The overall gain of the entire amplifier is the product of the first-stage gain, the second-stage gain, and the third-stage gain. A method called short-circuit time constants was used to determine the apropriate coupling and bypass capacitors. The overall circuit was then simulated by using NI Multisim. The magnitude of the overall gain of the circuit was obtained by performing an interactive analysis and simulation. The frequency response of the amplifier was obtained by performing an AC sweep analyses and simulation. It can be showed that the amplifier’s overall gain obtained from simulation is in agreement with the calculated results. The simulated result for the frequency responses were also in agreement with the requirement

High-Attenuation Wideband Active Common-Mode EMI Filter Section

A high-attenuation wideband active common-mode filter (ACF) section is presented. Each section is composed of an active capacitor and a small common-mode (CM) inductor. The active capacitor is realized by using several coupling capacitors and a class-A bipolar-junction-transistor based amplifier for its low-cost, fast response, and good immunity to high voltage transients. The structure of the amplifier consists of a common-collector amplifier and a high-gain common-emitter amplifier with an active load. The working bandwidth of the ACF ranges from 150 kHz to 30 MHz. By cascading several ACF sections, a multistage structure that exhibits high filtering attenuation can be designed. The number of cascaded sections is optimized by considering the required filtering attenuation. The performance of single-stage and multistage ACFs is evaluated on two commercial power supplies with rated power of 90 and 1000 W, respectively. The CM noise of the power supplies with the proposed ACF and with the original passive filters is compared. The results show that the physical volume of the ACF is significantly smaller than that of the passive filter, and the power dissipation of the ACF is similar to that of the passive filter.

Flat-High-Gain Design and Noise Optimization in SiGe Low-Noise Amplifier for S–K Band Applications

This paper presents an ultra-wideband (UWB) low-noise amplifier (LNA) with extremely flat-high-gain and low-noise figure (NF). In traditional resistive feedback topology, input matching, gain, and NF cannot be balanced. For better performance trade-offs in UWB design, a novel emitter-follower resistive feedback (EFRFB) is introduced, which utilizes a common-collector amplifier followed by a feedback resistor to flatten the gain (the ripple reduced by 2.3 dB) while alleviating the constraints between the gain and input matching. The enhanced gain without restraint by S11 is exactly required for noise reduction technology. Moreover, a peaking inductor and two resistors are adopted to improve bandwidth and output matching, respectively. The proposed LNA is implemented in a 0.18-μm SiGe BiCMOS technology and occupies 0.15 mm2 without pads. Measurements demonstrate that the LNA has a gain of 19.5 dB with ripple < 0.6 dB, a minimum NF of 2.8 dB from 2 to 22 GHz, and an input third-order intercept point (IIP3) of–7.6 dBm at 10 GHz while drawing 10.9 mA from a 3.3 V supply.

New 20 GHz push–push common‐collector Colpitts VCO

A wide-band push–push common-collector Colpitts voltage-controlled oscillator (VCO) usingimpedance peaking network and gain enhancing technique is proposed in this work.The impedance peaking network is introduced to increase the coupling factor ofthe differential inductor in the inductorcapacitor (LC) tank without sacrificing the quality factor. The impedancepeaking technique could guarantee the push–push VCO unconditionally oscillatingin a differential mode without degrading the phase noise performance. The gainenhancing technique employs an LC resonator in series with the emitterdegeneration resistor in the common-collector amplifier in the VCO core toimprove the VCO oscillating amplitude and then improve the phase noiseperformance. The proposed VCO oscillates at around 20 GHz with >10.5%frequency tuning range from 18.9 to 21.4 GHz across temperature from −40 to125°C. The measured phase noise is lower than −107 dBc/Hz at 1 MHz offset acrossthe entire working temperature (−40 125°C). The whole VCO dissipates 45 mA under3.3 V power supply, and the typical figure of merit is around −177.92.

Designing Wireless Charger Circuit for Hearing Aids Using Radio Frequency Waves

In this paper, an attempt has been made to produce a recipient system of wireless charge for a simple hearing aid so that electrical signal would be generated through detecting and receiving radio frequency waves (RF). The purpose of this design is to receive wireless charge for hearing aids and basically for any electronic device which is not required to a high energy for being setup. In this study, it has been demonstrated that as the amount of radio receiving energy increases, distance of receiver from antenna should be decreased; otherwise, either maximum amount of the receiving energy, or signal power density of the transmitter should be increased. Since it is impossible to be performed, it is decided to set up an energy receiving system constructed by rectenna and charge Circuit and to adjust their parameters to provide energy requirements for a device with low-power consumption. In this paper, different components of an energy receiving system from radio frequency band have been mentioned and a diagram block has been suggested. Subsequently, input impedance of designed antenna has been adjusted by provided relations. This impedance should be adjusted with the total impedance of regarded hearing aid Circuit by which the highest amount of received signal power is transferred to the battery of hearing aids. Received signal is converted to a dc voltage by rectifier diode. Finally, by applying a voltage regulator which has been designed using a common-collector amplifier not only the output voltage is kept constant, but the power is also strengthened. The battery of the hearing aids will be charged using the obtained power and voltage.

A very low noise preamplifier for extremely low frequency magnetic antenna

Besides the electrode-pair antenna, the magnetic antenna is also used for the extremely low frequency (ELF) submarine communication. To receive the weak ELF signals, the structure of a small sized magnetic antenna determines its specific electrical characteristics. The ELF magnetic antenna shows high internal resistance, alternating-current impedance, and a resonance frequency near the operating bandwidth. In accordance with the electrical characteristics of ELF magnetic antenna, a low noise preamplifier and frequency compensation circuit were designed and realized. The preamplifier is a three-stage negative feedback circuit, which is composed of parallel JFET, common-emitter amplifier with a Darlington structure and a common-collector amplifier in push-pull connection. And a frequency compensation circuit is cascaded to compensate the characteristic in low frequency range. In the operating bandwidth f = 30-200 Hz, the circuit has a gain of 39.4 dB. The equivalent input noise is 1.97 nV/√Hz and the frequency response keeps flat in operating bandwidth. The proposed preamplifier of the ELF magnetic antenna performs well in receiving ELF signals.

Experimental studies of frequency response and related properties of small-signal bipolar junction transistor amplifiers

Small-signal bipolar junction transistor (BJT) amplifiers, including common-emitter (C-E), common-base, and common-collector amplifiers, are the basic building blocks of many analog integrated circuits. An experimental investigation of the physical analysis of the frequency response and related parameters of these amplifiers have been performed in some details. The analysis uncovers fundamental reasons underlying the frequency response of the amplifiers. It indicates that although both the load resistance R L and the collector resistance R C, influence the voltage gain, for example, of a C-E amplifier, none of them should be very high to yield the highest value of the voltage gain. The distortion of the wave form of the output signal is found to be a serious problem in BJT amplifier circuits. This problem is particularly very serious in C-E amplifier with square wave signal and at high frequencies. Although by-pass capacitor plays a crucial role in minimizing this problem, the contribution of the coupling capacitors in this regard cannot be ruled out. Physical reasons of the distortion has been discussed in some details.