Hua Cao

Bio: Hua Cao is an academic researcher from Huazhong University of Science and Technology. The author has contributed to research in topics: CMOS & Current conveyor. The author has an hindex of 2, co-authored 2 publications receiving 15 citations.

A new CMOS electronically tunable current conveyor based on translinear circuits

Abstract: A new CMOS electronically tunable current conveyor (ECCII) based on translinear circuits is presented, with low power voltage (plusmn1.2 V) and continuous programmable current gain and highly linear wide tuning range. The current transfer ratio of the conveyor can be accurately controlled by the ratio of the DC bias currents. HSPICE simulation results using 0.35-mum CMOS process model confirm the expected good performance of the proposed ECCII in terms of linearity, frequency response and tunability.

A highly linear wide range continuous tuning CMOS OTA

Abstract: This paper introduces a new operational transconductance amplifier (OTA) that maintains a highly linear wide continuous tuning range and wide frequency response range, enabled by splitting linear voltage-to-current conversion and tuning into two different blocks. The input differential pair assures a wide input voltage swing via a fixed bias current, and a programmable-gain current amplifier working in saturation region can assure over three decades Gm tuning range and 119 MHz bandwidth. With plusmn1.5 V supply voltages, HSPICE simulation results using TSMC 0.35-mum CMOS process model confirm the expected good performance of the proposed OTA.

Precise Electronically Adjustable Oscillator Suitable for Quadrature Signal Generation Employing Active Elements with Current and Voltage Gain Control

Abstract: A new oscillator suitable for quadrature and multiphase signal generation is introduced in this contribution. A novel active element, called the controlled gain-buffered current and voltage amplifier (CG-BCVA) with electronic possibilities for current and voltage gain adjustment is implemented together with a controlled gain-current follower differential output buffered amplifier (CG-CFDOBA) for linear adjustment of the oscillation frequency and precise control of the oscillation condition in order to ensure a stable level of generated voltages and sufficient total harmonic distortion. The parameters of the oscillator are directly controllable electronically. Simultaneous changes of two current gains allow linear adjusting of the oscillation frequency, and a controllable voltage gain is intended to control the oscillation condition. A detailed comparison of the proposed circuits with recently developed and discovered solutions employing the same type of electronic control is provided and shows the useful features of the proposed oscillator and utilized methods of electronic control. Behavioral models based on commercially available ICs have been used for experimental purposes. CMOS implementation of active elements was introduced and utilized for additional simulations and studies. Non-ideal analysis, Monte Carlo statistical evaluations of simulated models, and further analyses were performed for the exact determination of the expected results. Laboratory experiments confirmed the workability and estimated behavior of the proposed circuit as well.

Study of Adjustable Gains for Control of Oscillation Frequency and Oscillation Condition in 3R-2C Oscillator

Abstract: An idea of adjustable gain in order to obtain controllable features is very useful for design of tunable oscillators. Several active elements with adjustable properties (current and voltage gain) are discussed in this paper. Three modified oscillator conceptions that are quite simple, directly electronically adjustable, providing independent control of oscillation condition and frequency were designed. Positive and negative aspects of presented method of control are discussed. Expected assumptions of adjustability are verified experimentally on one of the presented solutions.

New double current controlled cfa (dcc-cfa) based voltage-mode oscillator with independent electronic control of oscillation condition and frequency

Abstract: In this paper, a new electronically tunable quadrature oscillator (ETQO) based on two modified versions of current feedback amplifiers (CFAs), the so called double current controlled CFA (DCC-CFAs) is presented. The frequency of oscillation (FO) of the proposed voltage-mode (VM) ETQO is electronically adjustable by current gain or by varying the intrinsic resistance of the X terminal of the active element used. The condition of oscillation (CO) is adjustable by current gain independently with respect to frequency of oscillation. Simultaneous control of current gain and intrinsic resistance allows linear control of FO and provides extension of frequency tuning range. In the proposed circuit all the capacitors are grounded. The use of only grounded capacitors makes the proposed circuit ideal for integrated circuit implementation. The presented active element realized by using BiCMOS technology and the behavior of proposed circuit are discussed in details. The theoretical results are verified by SPICE simulations based on CMOS ON-Semi C5 0.5 µm and bipolar ultra high frequency transistor arrays Intersil HFA 3096 process parameters. K e y w o r d s: electronic control, sinusoidal oscillator, current feedback amplifier (CFA), double current controlled CFA (DCC-CFA)

Design of Novel Precise Quadrature Oscillators Employing ECCIIs with Electronic Control

Abstract: In this paper, an interesting design of precise quadrature oscillator employing electronically controllable current conveyors of the second generation (ECCII) is presented. The main pu ...